SlideShare a Scribd company logo
1 of 66
Download to read offline
Protein Digestion and Absorption
Return to TOC
Section 26.1
Copyright ©2016 Cengage Learning. All Rights Reserved. 1
Chapter 26
Chapter Outline
Copyright ©2016 Cengage Learning. All Rights Reserved. 2
26.1 Protein digestion and absorption
26.2 Amino acid utilization
26.3 Transamination and oxidative deamination
26.4 The urea cycle
26.5 Amino acid carbon skeletons
26.6 Amino acid biosynthesis
26.7 Hemoglobin catabolism
26.8 Proteins and the element sulfur
26.9 Interrelationships among metabolic pathways
26.10 B vitamins and protein metabolism
Protein Digestion and Absorption
Return to TOC
Section 26.1
Copyright ©2016 Cengage Learning. All Rights Reserved. 3
• Protein digestion starts in the stomach
– Dietary protein present in the stomach stimulates the
release of gastrin
• Gastrin promotes secretion of pepsinogen and HCl
– HCl in the stomach has 3 functions
• Antiseptic properties kill most bacteria
• Denaturing action “unwinds” globular properties
• Acidic property leads to activation of pepsinogen
– Pepsin affects the hydrolysis of 10% peptide bonds
Protein Digestion and Absorption
Return to TOC
Section 26.1
Copyright ©2016 Cengage Learning. All Rights Reserved. 4
• Production of secretin is stimulated by the passage of
small amounts of acidic protein content into the small
intestine
• Secretin stimulates bicarbonate (HCO3
-) production,
which in turn helps neutralize acidified gastric content
– Promotes secretion of pancreatic digestive enzymes
trypsin, chymotrypsin, and carboxypeptidase in their
inactive forms
Protein Digestion and Absorption
Return to TOC
Section 26.1
Protein Digestive Enzymes in the Intestine
• Proteolytic enzymes
– Enzymes that attack peptide bonds
– Pepsin
– Trypsin
– Chymotrypsin
• Zymogens
– Proteolytic enzymes produced in inactive form
Copyright ©2016 Cengage Learning. All Rights Reserved. 5
Protein Digestion and Absorption
Return to TOC
Section 26.1
Copyright ©2016 Cengage Learning. All Rights Reserved. 6
• Liberated amino acids are transported into the
bloodstream via active transport process
• The passage of polypeptides and small proteins across
the intestinal wall is uncommon in adults
– In infants, the transport of polypeptides allows the passage
of proteins such as antibodies in colostrum milk from a
mother to a nursing infant to build up immunologic
protection in the infant
Protein Digestion and Absorption
Return to TOC
Section 26.1
Figure 26.1 - Digestion of Protein in Humans
Copyright ©2016 Cengage Learning. All Rights Reserved. 7
Protein Digestion and Absorption
Return to TOC
Section 26.1
Protein digestion begins in the _____ and is
completed in the _____, resulting in the release of
amino acids.
a. mouth; stomach
b. mouth; small intestine
c. stomach; small intestine
d. small intestine; liver
Copyright ©2016 Cengage Learning. All Rights Reserved. 8
Protein Digestion and Absorption
Return to TOC
Section 26.1
Protein digestion begins in the _____ and is
completed in the _____, resulting in the release of
amino acids.
a. mouth; stomach
b. mouth; small intestine
c. stomach; small intestine
d. small intestine; liver
Copyright ©2016 Cengage Learning. All Rights Reserved. 9
Section 26.2
Amino Acid Utilization
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 10
Amino Acid Pool
• Amino acids formed through digestion process enter the
amino acid pool in the body
• Amino acid pool: The total supply of free amino acids
available for use in the human body
• Sources
– Dietary protein
– Protein turnover: The repetitive process in which proteins
are degraded and resynthesized
– Biosynthesis of amino acids in the liver
– Only nonessential amino acids are synthesized
Section 26.2
Amino Acid Utilization
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 11
Nitrogen Balance
• The state that results when the amount of nitrogen taken
into the human body as protein equals the amount of
nitrogen excreted from the body in waste materials
• Types of nitrogen imbalance
– Negative nitrogen imbalance - Protein degradation
exceeds protein synthesis
• Amount of nitrogen in urine exceeds consumed amount
• Results in tissue wasting
– Positive nitrogen imbalance - Rate of protein synthesis
(anabolism) is more than protein degradation (catabolism)
• Indicated by the synthesis of large amounts of tissue
Section 26.2
Amino Acid Utilization
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 12
Uses of Amino Acids in the Human Body
• Protein synthesis
‒ Uses approximately 75% of free amino acids
• Synthesis of non-protein nitrogen-containing compounds
‒ Synthesis of purines and pyrimidines
‒ Synthesis of heme for hemoglobin
• Synthesis of nonessential amino acids
‒ Essential amino acids cannot be synthesized due to the
lack of an appropriate carbon chain
• Production of energy
‒ Amino acids are not stored in the body
• Excesses are degraded
• Each amino acid has a unique degradation pathway
Section 26.2
Amino Acid Utilization
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 13
Degradation Pathways
• The amino nitrogen atom is removed and excreted from
the body as urea
• The remaining carbon skeleton is converted to pyruvate,
acetyl CoA, or a citric acid cycle intermediate
Section 26.2
Amino Acid Utilization
Return to TOC
Amino acids produced during protein digestion
enter the _____ of the body.
a. energy production pool
b. amino acid pool
c. protein synthesis pool
d. nitrogen balance pool
Copyright ©2016 Cengage Learning. All Rights Reserved. 14
Section 26.2
Amino Acid Utilization
Return to TOC
Amino acids produced during protein digestion
enter the _____ of the body.
a. energy production pool
b. amino acid pool
c. protein synthesis pool
d. nitrogen balance pool
Copyright ©2016 Cengage Learning. All Rights Reserved. 15
Section 26.3
Transamination and Oxidative Deamination
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 16
• Degradation of an amino acid takes place in two stages
̶ Removal of the α-amino group
̶ Degradation of the remaining carbon skeleton
• Removal of amino groups requires:
– Transamination: A biochemical reaction characterized by
the interchange of the amino group in an α-amino acid
with the keto group in an α-keto acid
– Oxidative deamination
Section 26.3
Transamination and Oxidative Deamination
Return to TOC
Glutamate Production via Transamination
• Glutamate is produced through transamination when α-
ketoglutarate is the amino group acceptor
Copyright ©2016 Cengage Learning. All Rights Reserved. 17
Section 26.3
Transamination and Oxidative Deamination
Return to TOC
Aspartate Production via Transamination
• This occurs when glutamate is the reacting acid and
oxaloacetate is the reacting keto acid
Copyright ©2016 Cengage Learning. All Rights Reserved. 18
Section 26.3
Transamination and Oxidative Deamination
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 19
Ammonium Production via Oxidative Deamination
• Oxidative deamination is a biochemical reaction in which
an α-amino acid is converted to an α-keto acid with
release of an ammonium ion
– Occurs in the mitochondria of the liver and kidney
Section 26.3
Transamination and Oxidative Deamination
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 20
Practice Exercise
Indicate whether each of the following reaction characteristics is
associated with the process of transamination or with the
process of oxidative deamination:
a. One of the reactants is a keto acid and one of the products is a keto acid.
b. Enzymes with a specificity toward α-ketoglutarate are often active.
c. NAD is used as an oxidizing agent.
d. An aminotransferase enzyme is active.
Section 26.3
Transamination and Oxidative Deamination
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 21
Practice Exercise
Indicate whether each of the following reaction characteristics is
associated with the process of transamination or with the
process of oxidative deamination:
a. One of the reactants is a keto acid and one of the products is a keto acid.
b. Enzymes with a specificity toward α-ketoglutarate are often active.
c. NAD is used as an oxidizing agent.
d. An aminotransferase enzyme is active.
Answers:
a. Transamination
b. Transamination
c. Oxidative deamination
d. Transamination
Section 26.3
Transamination and Oxidative Deamination
Return to TOC
What two types of biochemical reactions are
required for the removal of the amino group from
most amino acids?
a. Amination and reductive deamination
b. Amination and oxidative deamination
c. Transamination and reductive deamination
d. Transamination and oxidative deamination
Copyright ©2016 Cengage Learning. All Rights Reserved. 22
Section 26.3
Transamination and Oxidative Deamination
Return to TOC
What two types of biochemical reactions are
required for the removal of the amino group from
most amino acids?
a. Amination and reductive deamination
b. Amination and oxidative deamination
c. Transamination and reductive deamination
d. Transamination and oxidative deamination
Copyright ©2016 Cengage Learning. All Rights Reserved. 23
Section 26.4
The Urea Cycle
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 24
• The net effect of transamination and deamination
reactions is the production of ammonium ions and
aspartate
• Urea cycle: A series of biochemical reactions in which
urea is produced from ammonium ions and aspartate as
nitrogen sources
• Urea produced in the liver is transported via blood to the
kidneys and eliminated from the body in urine
• Urea is an odorless white solid with a salty taste, has a
melting point of 133oC, and is soluble in water
Section 26.4
The Urea Cycle
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 25
Carbamoyl Phosphate
• One of the sources of fuel for the urea cycle
• Two ATP molecules are expended in the formation of
one carbamoyl phosphate molecule
• It contains a high-energy phosphate bond
• It is formed in the mitochondrial matrix
Section 26.4
The Urea Cycle
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 26
Steps of the Urea Cycle
• Stage 1 - Carbamoyl group transfer
– The carbamoyl group of carbamoyl phosphate is
transferred to ornithine to form citrulline
• Stage 2 - Citrulline–aspartate condensation
– Citrulline is transported into the cytosol and reacts with
aspartate to produce argininosuccinate synthetase,
utilizing ATP
• Stage 3 - Argininosuccinate cleavage
– Argininosuccinate is cleaved to arginine and fumarate by
the enzyme argininosuccinate lyase
Section 26.4
The Urea Cycle
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 27
Steps of the Urea Cycle
• Stage 4 - Urea from arginine hydrolysis
– Hydrolysis of arginine produces urea and regenerates
ornithine under the influence of arginase
– The oxygen atom present in urea comes from water
– Ornithine is transported back to mitochondria to be used
in the urea cycle
Section 26.4
The Urea Cycle
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 28
Urea Cycle Net Reaction
• The equivalent of four ATP molecules is expended in the
production of one urea molecule
– Two molecules of ATP are consumed in the
production of carbamoyl phosphate
– The equivalent of two ATP molecules is consumed in
step two of the urea cycle to give AMP and the PPi
Section 26.4
The Urea Cycle
Return to TOC
Figure 26.6 - Conversion of Carbamoyl Phosphate to
Urea
Copyright ©2016 Cengage Learning. All Rights Reserved. 29
Section 26.4
The Urea Cycle
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 30
Linkage Between the Urea and Citric Acid Cycles
• Fumarate produced is ultimately converted to asparte
• Aspartate re-enters the urea cycle at step two
Section 26.4
The Urea Cycle
Return to TOC
The net effect of amino acid degradation is the
production of the ammonium ion, which is toxic.
How is the ammonium ion eliminated from the
body?
a. It is biosynthesized for the production of nonessential
amino acids.
b. It is recycled in the production of amino acids.
c. It is converted to urea in the urea cycle and excreted in
the urine.
d. Both (b) and (c).
Copyright ©2016 Cengage Learning. All Rights Reserved. 31
Section 26.4
The Urea Cycle
Return to TOC
The net effect of amino acid degradation is the
production of the ammonium ion, which is toxic.
How is the ammonium ion eliminated from the
body?
a. It is biosynthesized for the production of nonessential
amino acids.
b. It is recycled in the production of amino acids.
c. It is converted to urea in the urea cycle and excreted in
the urine.
d. Both (b) and (c).
Copyright ©2016 Cengage Learning. All Rights Reserved. 32
Section 26.5
Amino Acid Carbon Skeletons
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 33
• Transamination/oxidative deamination removes the
amino group from an amino acid
– An α-keto acid that contains the skeleton of the amino acid
is produced
• Each of the 20 amino acids undergo a different
degradation process
– Products formed are among a group of seven
intermediates
• Four products are intermediates in the citric acid cycle
• Three products are pyruvate, acetyl CoA, and acetoacetyl
CoA
Section 26.5
Amino Acid Carbon Skeletons
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 34
• The amino acids converted to citric acid cycle
intermediates can serve as glucose precursors
– Glucogenic amino acid: An amino acid that has a
carbon-containing degradation product that can be used to
produce glucose via gluconeogenesis
• The amino acids converted to acetyl CoA or acetoacetyl
CoA can contribute to the formation of fatty acids
– Ketogenic amino acid: An amino acid that has a carbon-
containing degradation product that can be used to
produce ketone bodies
Section 26.5
Amino Acid Carbon Skeletons
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 35
Figure 26.9 - Fates of Carbon Skeletons of Amino Acids
Section 26.5
Amino Acid Carbon Skeletons
Return to TOC
What are the four intermediates that contain the
carbon skeletons from amino acid degradation in
the citric acid cycle?
a. Citric acid, α-ketoglutarate, acetyl CoA, and fumarate
b. α-Ketoglutarate, succinyl CoA, fumarate, and
oxaloacetate
c. α-Ketoglutarate, acetyl CoA, succinyl CoA, and
fumarate
d. Citric acid, succinyl CoA, fumarate, and oxaloacetate
Copyright ©2016 Cengage Learning. All Rights Reserved. 36
Section 26.5
Amino Acid Carbon Skeletons
Return to TOC
What are the four intermediates that contain the
carbon skeletons from amino acid degradation in
the citric acid cycle?
a. Citric acid, α-ketoglutarate, acetyl CoA, and fumarate
b. α-Ketoglutarate, succinyl CoA, fumarate, and
oxaloacetate
c. α-Ketoglutarate, acetyl CoA, succinyl CoA, and
fumarate
d. Citric acid, succinyl CoA, fumarate, and oxaloacetate
Copyright ©2016 Cengage Learning. All Rights Reserved. 37
Section 26.6
Amino Acid Biosynthesis
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 38
• Nonessential amino acids are synthesized in fewer steps
than essential amino acids
• The primary source of essential amino acids for humans
and animals is plants
Section 26.6
Amino Acid Biosynthesis
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 39
Figure 26.10 - Summary of the Starting Materials for the
Biosynthesis of the 11 Nonessential Amino Acids
Section 26.6
Amino Acid Biosynthesis
Return to TOC
Which of the following statements is/are true of
amino acids?
a. Nonessential amino acids are synthesized in fewer
steps than essential amino acids.
b. Most bacteria and plants synthesize all amino acids via
pathways that are not present in humans.
c. Plants are the major source of the essential amino acids
in humans and animals.
d. All the above.
Copyright ©2016 Cengage Learning. All Rights Reserved. 40
Section 26.6
Amino Acid Biosynthesis
Return to TOC
Which of the following statements is/are true of
amino acids?
a. Nonessential amino acids are synthesized in fewer
steps than essential amino acids.
b. Most bacteria and plants synthesize all amino acids via
pathways that are not present in humans.
c. Plants are the major source of the essential amino acids
in humans and animals.
d. All the above.
Copyright ©2016 Cengage Learning. All Rights Reserved. 41
Section 26.7
Hemoglobin Catabolism
Return to TOC
Red Blood Cells
• They are highly specialized cells whose primary function
is to deliver oxygen to cells and remove carbon dioxide
from body tissues
• Mature red blood cells have no nucleus or DNA
– Filled with hemoglobin
• Red blood cells are formed in the bone marrow
– Approximately 200 billion new red blood cells are formed
daily
• The life span of a red blood cell is approximately four
months
Copyright ©2016 Cengage Learning. All Rights Reserved. 42
Section 26.7
Hemoglobin Catabolism
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 43
• Hemoglobin is a conjugated protein with two
components
– Globin - The protein portion
– Heme - The prosthetic group
• Iron atom present in heme interacts with oxygen
– A reversible complex is formed
Section 26.7
Hemoglobin Catabolism
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 44
• Old RBCs are broken down in the spleen and liver
• Degradation of hemoglobin
– Globin protein part is converted to amino acids, which
become part of the amino acid pool
– The iron atom becomes part of ferritin
• An iron-storage protein
– The tetrapyrrole carbon arrangement of heme is degraded
to bile pigments
• Eliminated in feces or urine
Section 26.7
Hemoglobin Catabolism
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 45
Bile Pigments
• Colored tetrapyrrole degradation products present in bile
• Types of bile pigments
– Biliverdin - Green in color
– Bilirubin - Reddish orange in color
– Stercobilin - Brownish in color
– Urobilin - Yellow in color
Section 26.7
Hemoglobin Catabolism
Return to TOC
Copyright ©2016 Cengage Learning. All Rights Reserved. 46
Bile Pigments
• Daily normal excretion of bile pigments
– 1–2 mg in urine
– 250–350 mg in feces
• Jaundice
– Caused by an imbalance between the formation and
removal of bilirubin
– Gives the skin and white of the eye the characteristic
yellow tint of the illness
Section 26.7
Hemoglobin Catabolism
Return to TOC
Degradation of heme from hemolysis produces the
product _____, which is converted to _____.
a. bilirubin; biliverdin
b. biliverdin; bilirubin
c. bilirubin; urobilin
d. stercobilin; urobilin
Copyright ©2016 Cengage Learning. All Rights Reserved. 47
Section 26.7
Hemoglobin Catabolism
Return to TOC
Degradation of heme from hemolysis produces the
product _____, which is converted to _____.
a. bilirubin; biliverdin
b. biliverdin; bilirubin
c. bilirubin; urobilin
d. stercobilin; urobilin
Copyright ©2016 Cengage Learning. All Rights Reserved. 48
Section 26.8
Proteins and the Element Sulfur
Return to TOC
Biodegradation of Cysteine
• Occurs in two steps
– A transamination reaction
– Release of —SH
Copyright ©2016 Cengage Learning. All Rights Reserved. 49
Section 26.8
Proteins and the Element Sulfur
Return to TOC
Biosynthesis of Cysteine
• Serine is the precursor
• Serine is converted to cysteine in two steps
– Activation of serine by an acetyl CoA molecule
– Sulfhydration with hydrogen sulphide
• Hydrogen sulphide is produced by sulfate assimilation
Copyright ©2016 Cengage Learning. All Rights Reserved. 50
Section 26.8
Proteins and the Element Sulfur
Return to TOC
Figure 26.13 (a) - Steps 1 and 2 of Sulfate Assimilation
Copyright ©2016 Cengage Learning. All Rights Reserved. 51
Section 26.8
Proteins and the Element Sulfur
Return to TOC
Figure 26.13 (b) - Steps 3 and 4 of Sulfate Assimilation
Copyright ©2016 Cengage Learning. All Rights Reserved. 52
Section 26.8
Proteins and the Element Sulfur
Return to TOC
Hydrogen Sulfide as a Biochemical Signalling Agent
Copyright ©2016 Cengage Learning. All Rights Reserved. 53
• It regulates vascular blood flow and blood pressure
– Acts as a smooth muscle relaxant and vasodilator
• It influences brain function
– Brain levels of H2S are lower than normal in cases of
Alzheimer’s disease
• It influences insulin levels in type I diabetes
– Excess of H2S leads to reduced insulin production
Section 26.8
Proteins and the Element Sulfur
Return to TOC
In degradation of the sulfur-containing amino acid
cysteine, the sulfur is released in the
form of:
a. hydrogen sulfide.
b. sulfate ion.
c. sulfur dioxide.
d. none of the above.
Copyright ©2016 Cengage Learning. All Rights Reserved. 54
Section 26.8
Proteins and the Element Sulfur
Return to TOC
In degradation of the sulfur-containing amino acid
cysteine, the sulfur is released in the
form of:
a. hydrogen sulfide.
b. sulfate ion.
c. sulfur dioxide.
d. none of the above.
Copyright ©2016 Cengage Learning. All Rights Reserved. 55
Section 26.9
Interrelationships Among Metabolic Pathways
Return to TOC
• The metabolic pathways of carbohydrates, lipids, and
proteins are integrally linked to one another
− A change in one pathway can affect many other pathways
• Examples
− Feasting - Over-eating
− Causes the body to store a limited amount as glycogen and
the rest as fat
− Fasting - Food is not ingested
− The body uses its stored glycogen and fat for energy
− Starvation - Prolonged fasting
− Body protein is broken down to amino acids to synthesize
glucose
Copyright ©2016 Cengage Learning. All Rights Reserved. 56
Section 26.9
Interrelationships Among Metabolic Pathways
Return to TOC
During starvation, what is used as a source of
energy after the glycogen stores have been
depleted?
a. Amino acids of degraded proteins which are used to
synthesize glucose
b. Body fats which are converted to ketone bodies and
used as a source of brain energy
c. Glycogen stores are never depleted
d. Both (a) and (b)
Copyright ©2016 Cengage Learning. All Rights Reserved. 57
Section 26.9
Interrelationships Among Metabolic Pathways
Return to TOC
During starvation, what is used as a source of
energy after the glycogen stores have been
depleted?
a. Amino acids of degraded proteins which are used to
synthesize glucose
b. Body fats which are converted to ketone bodies and
used as a source of brain energy
c. Glycogen stores are never depleted
d. Both (a) and (b)
Copyright ©2016 Cengage Learning. All Rights Reserved. 58
Section 26.10
B Vitamins and Protein Metabolism
Return to TOC
• All eight B vitamins participate in various pathways of
protein metabolism
– Niacin
• Oxidative deamination reactions
– PLP
• Transamination reactions
Copyright ©2016 Cengage Learning. All Rights Reserved. 59
Section 26.10
B Vitamins and Protein Metabolism
Return to TOC
Figure 26.15 - Involvement of B Vitamins in Protein
Metabolism
Copyright ©2016 Cengage Learning. All Rights Reserved. 60
Section 26.10
B Vitamins and Protein Metabolism
Return to TOC
Transamination reactions require the cofactor PLP,
which involves:
a. folate.
b. riboflavin.
c. vitamin B6.
d. none of the above.
Copyright ©2016 Cengage Learning. All Rights Reserved. 61
Section 26.10
B Vitamins and Protein Metabolism
Return to TOC
Transamination reactions require the cofactor PLP,
which involves:
a. folate.
b. riboflavin.
c. vitamin B6.
d. none of the above.
Copyright ©2016 Cengage Learning. All Rights Reserved. 62
Chapter 26
What best describes what happens to the protein
after eating a high-protein meal?
a. Protein digestion begins in the stomach and then moves to the
small intestine where complete digestion occurs. The free amino
acids are stored in the amino acid pool.
b. Proteins are denatured in the stomach and are then moved to the
small intestine for complete digestion.
c. Protein digestion begins in the mouth and then moves to the
stomach for complete digestion by the enzyme pepsin. The free
amino acids are then moved to the small intestine and stored in the
amino acid pool.
d. Protein digestion begins in the mouth, is continued in the stomach,
and is completed in the small intestine.
Copyright ©2016 Cengage Learning. All Rights Reserved. 63
Chapter 26
What best describes what happens to the protein
after eating a high-protein meal?
a. Protein digestion begins in the stomach and then moves to the
small intestine where complete digestion occurs. The free amino
acids are stored in the amino acid pool.
b. Proteins are denatured in the stomach and are then moved to the
small intestine for complete digestion.
c. Protein digestion begins in the mouth and then moves to the
stomach for complete digestion by the enzyme pepsin. The free
amino acids are then moved to the small intestine and stored in the
amino acid pool.
d. Protein digestion begins in the mouth, is continued in the stomach,
and is completed in the small intestine.
Copyright ©2016 Cengage Learning. All Rights Reserved. 64
Chapter 26
In the early 1990s, nitric oxide (NO) was
discovered in the body as a gaseous chemical
messenger. What effect does nitric oxide have in
the body?
a. It stimulates the urea cycle to ensure proper functioning in the
removal of the toxic ammonium ion.
b. It plays a part in maintaining blood pressure and is found in the
brain where it may play a part in long-term memory.
c. It is rapidly converted to an amino group which is used in amino
acid synthesis.
d. It carries messages into the mitochondria to signal the production
of large amounts of energy when called for by the hormone
epinephrine.
Copyright ©2016 Cengage Learning. All Rights Reserved. 65
Chapter 26
In the early 1990s, nitric oxide (NO) was
discovered in the body as a gaseous chemical
messenger. What effect does nitric oxide have in
the body?
a. It stimulates the urea cycle to ensure proper functioning in the
removal of the toxic ammonium ion.
b. It plays a part in maintaining blood pressure and is found in the
brain where it may play a part in long-term memory.
c. It is rapidly converted to an amino group which is used in amino
acid synthesis.
d. It carries messages into the mitochondria to signal the production
of large amounts of energy when called for by the hormone
epinephrine.
Copyright ©2016 Cengage Learning. All Rights Reserved. 66

More Related Content

What's hot

Amino acids metabolism
Amino acids metabolismAmino acids metabolism
Amino acids metabolismAbhra Ghosh
 
Nomenclature and Classification of enzyme
Nomenclature and Classification of enzymeNomenclature and Classification of enzyme
Nomenclature and Classification of enzymeFizza Mehwish
 
Vitamins & Coenzymes
Vitamins & CoenzymesVitamins & Coenzymes
Vitamins & CoenzymesÜlger Ahmet
 
Urea Cycle | Energetics of Urea Cycle | Regulation of Urea Cycle | Metabolic ...
Urea Cycle | Energetics of Urea Cycle | Regulation of Urea Cycle | Metabolic ...Urea Cycle | Energetics of Urea Cycle | Regulation of Urea Cycle | Metabolic ...
Urea Cycle | Energetics of Urea Cycle | Regulation of Urea Cycle | Metabolic ...kiransharma204
 
Chem 45 Biochemistry: Stoker Chapter 20 Proteins
Chem 45 Biochemistry: Stoker Chapter 20 ProteinsChem 45 Biochemistry: Stoker Chapter 20 Proteins
Chem 45 Biochemistry: Stoker Chapter 20 ProteinsShaina Mavreen Villaroza
 
Amino acid catabolism- Part-1
Amino acid catabolism- Part-1Amino acid catabolism- Part-1
Amino acid catabolism- Part-1Namrata Chhabra
 
Protein & Amino Acid Metabolism
Protein & Amino Acid MetabolismProtein & Amino Acid Metabolism
Protein & Amino Acid MetabolismSmitaPakhmode1
 
Enzyme introduction, nomenclature, properties, and classification
Enzyme introduction, nomenclature, properties, and classification  Enzyme introduction, nomenclature, properties, and classification
Enzyme introduction, nomenclature, properties, and classification Nandeesha s
 
Biochemistry lecture notes metabolism_tca cycle; glyoxalate cycle
Biochemistry lecture notes metabolism_tca cycle; glyoxalate cycleBiochemistry lecture notes metabolism_tca cycle; glyoxalate cycle
Biochemistry lecture notes metabolism_tca cycle; glyoxalate cycleRengesh Balakrishnan
 
Amino acid metabolism | Transamination | Deamination |
Amino acid metabolism | Transamination | Deamination |Amino acid metabolism | Transamination | Deamination |
Amino acid metabolism | Transamination | Deamination |kiransharma204
 

What's hot (20)

Amino acids metabolism
Amino acids metabolismAmino acids metabolism
Amino acids metabolism
 
Krebs cycle TCA Cycle
Krebs cycle TCA CycleKrebs cycle TCA Cycle
Krebs cycle TCA Cycle
 
Nomenclature and Classification of enzyme
Nomenclature and Classification of enzymeNomenclature and Classification of enzyme
Nomenclature and Classification of enzyme
 
Vitamins & Coenzymes
Vitamins & CoenzymesVitamins & Coenzymes
Vitamins & Coenzymes
 
Amino acid catabolism
Amino acid catabolismAmino acid catabolism
Amino acid catabolism
 
Urea Cycle | Energetics of Urea Cycle | Regulation of Urea Cycle | Metabolic ...
Urea Cycle | Energetics of Urea Cycle | Regulation of Urea Cycle | Metabolic ...Urea Cycle | Energetics of Urea Cycle | Regulation of Urea Cycle | Metabolic ...
Urea Cycle | Energetics of Urea Cycle | Regulation of Urea Cycle | Metabolic ...
 
Chem 45 Biochemistry: Stoker Chapter 20 Proteins
Chem 45 Biochemistry: Stoker Chapter 20 ProteinsChem 45 Biochemistry: Stoker Chapter 20 Proteins
Chem 45 Biochemistry: Stoker Chapter 20 Proteins
 
Amino acid catabolism- Part-1
Amino acid catabolism- Part-1Amino acid catabolism- Part-1
Amino acid catabolism- Part-1
 
Enzyme kinetics
Enzyme kineticsEnzyme kinetics
Enzyme kinetics
 
Urea cycle disorder
Urea cycle disorderUrea cycle disorder
Urea cycle disorder
 
Amino acids
Amino acidsAmino acids
Amino acids
 
Vitamins as coenzymes
Vitamins as coenzymesVitamins as coenzymes
Vitamins as coenzymes
 
Chem 45 Biochemistry: Carbohydrates
Chem 45 Biochemistry: CarbohydratesChem 45 Biochemistry: Carbohydrates
Chem 45 Biochemistry: Carbohydrates
 
Lipid Metabolism
Lipid MetabolismLipid Metabolism
Lipid Metabolism
 
protein metabolism
protein metabolism protein metabolism
protein metabolism
 
Ketone bodies
Ketone bodiesKetone bodies
Ketone bodies
 
Protein & Amino Acid Metabolism
Protein & Amino Acid MetabolismProtein & Amino Acid Metabolism
Protein & Amino Acid Metabolism
 
Enzyme introduction, nomenclature, properties, and classification
Enzyme introduction, nomenclature, properties, and classification  Enzyme introduction, nomenclature, properties, and classification
Enzyme introduction, nomenclature, properties, and classification
 
Biochemistry lecture notes metabolism_tca cycle; glyoxalate cycle
Biochemistry lecture notes metabolism_tca cycle; glyoxalate cycleBiochemistry lecture notes metabolism_tca cycle; glyoxalate cycle
Biochemistry lecture notes metabolism_tca cycle; glyoxalate cycle
 
Amino acid metabolism | Transamination | Deamination |
Amino acid metabolism | Transamination | Deamination |Amino acid metabolism | Transamination | Deamination |
Amino acid metabolism | Transamination | Deamination |
 

Similar to Protein-Metabolism.pptx

Beta oxidation & protein catabolism
Beta oxidation & protein catabolismBeta oxidation & protein catabolism
Beta oxidation & protein catabolismobanbrahma
 
Amino acid meatbolism and urea cycle(1)
Amino acid meatbolism and urea cycle(1)Amino acid meatbolism and urea cycle(1)
Amino acid meatbolism and urea cycle(1)sameenakhan420
 
Protein Metabolism .ppt
Protein Metabolism .pptProtein Metabolism .ppt
Protein Metabolism .pptawaissaleem42
 
Beta oxidation & protein catabolism
Beta oxidation & protein catabolismBeta oxidation & protein catabolism
Beta oxidation & protein catabolismobanbrahma
 
Catabolism of Amino Acids.ppt degradation of aminoacids
Catabolism of Amino Acids.ppt degradation of aminoacidsCatabolism of Amino Acids.ppt degradation of aminoacids
Catabolism of Amino Acids.ppt degradation of aminoacidsSudha Sudha
 
Chem 45 Biochemistry: Stoker chapter 23 Metabolism Introduction
Chem 45 Biochemistry: Stoker chapter 23 Metabolism IntroductionChem 45 Biochemistry: Stoker chapter 23 Metabolism Introduction
Chem 45 Biochemistry: Stoker chapter 23 Metabolism IntroductionShaina Mavreen Villaroza
 
Amino acid meatbolism and Urea cycle-1.pptx
Amino acid meatbolism and Urea cycle-1.pptxAmino acid meatbolism and Urea cycle-1.pptx
Amino acid meatbolism and Urea cycle-1.pptxABIDOFFICIALCHANNEL
 
The Pathways of Amino Acid Metabolism.pptx
The Pathways of Amino Acid Metabolism.pptxThe Pathways of Amino Acid Metabolism.pptx
The Pathways of Amino Acid Metabolism.pptxAtulSingh77625
 
Urea cycle.. lgis
Urea cycle.. lgisUrea cycle.. lgis
Urea cycle.. lgisZahid Azeem
 
Nitrogen metabolism (metabolic fate of amino acid, catabolism of amino acid, ...
Nitrogen metabolism (metabolic fate of amino acid, catabolism of amino acid, ...Nitrogen metabolism (metabolic fate of amino acid, catabolism of amino acid, ...
Nitrogen metabolism (metabolic fate of amino acid, catabolism of amino acid, ...anamsharif
 
Lec 3 level 3-nu(nitrogen metabolism)
Lec 3  level 3-nu(nitrogen metabolism)Lec 3  level 3-nu(nitrogen metabolism)
Lec 3 level 3-nu(nitrogen metabolism)dream10f
 
1. METABOLISM_dalam tubuh manusia_123.pptx
1. METABOLISM_dalam tubuh manusia_123.pptx1. METABOLISM_dalam tubuh manusia_123.pptx
1. METABOLISM_dalam tubuh manusia_123.pptxagussuprijono5
 
Respiration5beyondglucose
Respiration5beyondglucoseRespiration5beyondglucose
Respiration5beyondglucosehursmi
 
Lec3 level3-nunitrogenmetabolism-130204053253-phpapp01
Lec3 level3-nunitrogenmetabolism-130204053253-phpapp01Lec3 level3-nunitrogenmetabolism-130204053253-phpapp01
Lec3 level3-nunitrogenmetabolism-130204053253-phpapp01Cleophas Rwemera
 
Metabolic pathways with particular relevance to environmental biotechnology.pptx
Metabolic pathways with particular relevance to environmental biotechnology.pptxMetabolic pathways with particular relevance to environmental biotechnology.pptx
Metabolic pathways with particular relevance to environmental biotechnology.pptxJerlinMary2
 
Lec3 level3-deproteinmetabolismureacycle-130202042721-phpapp02
Lec3 level3-deproteinmetabolismureacycle-130202042721-phpapp02Lec3 level3-deproteinmetabolismureacycle-130202042721-phpapp02
Lec3 level3-deproteinmetabolismureacycle-130202042721-phpapp02Cleophas Rwemera
 
2017 biochemistry week 16 chapter 22 biosynthesis of amino acids and nucleoti...
2017 biochemistry week 16 chapter 22 biosynthesis of amino acids and nucleoti...2017 biochemistry week 16 chapter 22 biosynthesis of amino acids and nucleoti...
2017 biochemistry week 16 chapter 22 biosynthesis of amino acids and nucleoti...noviyandarmawan1
 

Similar to Protein-Metabolism.pptx (20)

Protein metabolism
Protein metabolismProtein metabolism
Protein metabolism
 
Protein metabolism.ppt
Protein metabolism.pptProtein metabolism.ppt
Protein metabolism.ppt
 
Beta oxidation & protein catabolism
Beta oxidation & protein catabolismBeta oxidation & protein catabolism
Beta oxidation & protein catabolism
 
Amino acid meatbolism and urea cycle(1)
Amino acid meatbolism and urea cycle(1)Amino acid meatbolism and urea cycle(1)
Amino acid meatbolism and urea cycle(1)
 
Protein Metabolism .ppt
Protein Metabolism .pptProtein Metabolism .ppt
Protein Metabolism .ppt
 
Beta oxidation & protein catabolism
Beta oxidation & protein catabolismBeta oxidation & protein catabolism
Beta oxidation & protein catabolism
 
Catabolism of Amino Acids.ppt degradation of aminoacids
Catabolism of Amino Acids.ppt degradation of aminoacidsCatabolism of Amino Acids.ppt degradation of aminoacids
Catabolism of Amino Acids.ppt degradation of aminoacids
 
Chem 45 Biochemistry: Stoker chapter 23 Metabolism Introduction
Chem 45 Biochemistry: Stoker chapter 23 Metabolism IntroductionChem 45 Biochemistry: Stoker chapter 23 Metabolism Introduction
Chem 45 Biochemistry: Stoker chapter 23 Metabolism Introduction
 
Amino acid meatbolism and Urea cycle-1.pptx
Amino acid meatbolism and Urea cycle-1.pptxAmino acid meatbolism and Urea cycle-1.pptx
Amino acid meatbolism and Urea cycle-1.pptx
 
Amino acid meatbolism and urea cycle
Amino acid meatbolism and urea cycleAmino acid meatbolism and urea cycle
Amino acid meatbolism and urea cycle
 
The Pathways of Amino Acid Metabolism.pptx
The Pathways of Amino Acid Metabolism.pptxThe Pathways of Amino Acid Metabolism.pptx
The Pathways of Amino Acid Metabolism.pptx
 
Urea cycle.. lgis
Urea cycle.. lgisUrea cycle.. lgis
Urea cycle.. lgis
 
Nitrogen metabolism (metabolic fate of amino acid, catabolism of amino acid, ...
Nitrogen metabolism (metabolic fate of amino acid, catabolism of amino acid, ...Nitrogen metabolism (metabolic fate of amino acid, catabolism of amino acid, ...
Nitrogen metabolism (metabolic fate of amino acid, catabolism of amino acid, ...
 
Lec 3 level 3-nu(nitrogen metabolism)
Lec 3  level 3-nu(nitrogen metabolism)Lec 3  level 3-nu(nitrogen metabolism)
Lec 3 level 3-nu(nitrogen metabolism)
 
1. METABOLISM_dalam tubuh manusia_123.pptx
1. METABOLISM_dalam tubuh manusia_123.pptx1. METABOLISM_dalam tubuh manusia_123.pptx
1. METABOLISM_dalam tubuh manusia_123.pptx
 
Respiration5beyondglucose
Respiration5beyondglucoseRespiration5beyondglucose
Respiration5beyondglucose
 
Lec3 level3-nunitrogenmetabolism-130204053253-phpapp01
Lec3 level3-nunitrogenmetabolism-130204053253-phpapp01Lec3 level3-nunitrogenmetabolism-130204053253-phpapp01
Lec3 level3-nunitrogenmetabolism-130204053253-phpapp01
 
Metabolic pathways with particular relevance to environmental biotechnology.pptx
Metabolic pathways with particular relevance to environmental biotechnology.pptxMetabolic pathways with particular relevance to environmental biotechnology.pptx
Metabolic pathways with particular relevance to environmental biotechnology.pptx
 
Lec3 level3-deproteinmetabolismureacycle-130202042721-phpapp02
Lec3 level3-deproteinmetabolismureacycle-130202042721-phpapp02Lec3 level3-deproteinmetabolismureacycle-130202042721-phpapp02
Lec3 level3-deproteinmetabolismureacycle-130202042721-phpapp02
 
2017 biochemistry week 16 chapter 22 biosynthesis of amino acids and nucleoti...
2017 biochemistry week 16 chapter 22 biosynthesis of amino acids and nucleoti...2017 biochemistry week 16 chapter 22 biosynthesis of amino acids and nucleoti...
2017 biochemistry week 16 chapter 22 biosynthesis of amino acids and nucleoti...
 

More from RexBlancoNuez

Identifying of Pre-referral Treatment.ppt
Identifying of Pre-referral Treatment.pptIdentifying of Pre-referral Treatment.ppt
Identifying of Pre-referral Treatment.pptRexBlancoNuez
 
laos police system, president,locationppt.pptx
laos police system, president,locationppt.pptxlaos police system, president,locationppt.pptx
laos police system, president,locationppt.pptxRexBlancoNuez
 
POSITIONING-A-PATIENT-IN-BED.pptx
POSITIONING-A-PATIENT-IN-BED.pptxPOSITIONING-A-PATIENT-IN-BED.pptx
POSITIONING-A-PATIENT-IN-BED.pptxRexBlancoNuez
 
pdfslide.net_-parts-of-the-skeletal-system-bones-skeleton-joints-cartilages.ppt
pdfslide.net_-parts-of-the-skeletal-system-bones-skeleton-joints-cartilages.pptpdfslide.net_-parts-of-the-skeletal-system-bones-skeleton-joints-cartilages.ppt
pdfslide.net_-parts-of-the-skeletal-system-bones-skeleton-joints-cartilages.pptRexBlancoNuez
 
14.0 The Lymphatic System.pdf
14.0 The Lymphatic System.pdf14.0 The Lymphatic System.pdf
14.0 The Lymphatic System.pdfRexBlancoNuez
 
Chapter_4__Enzymes_and_Vitamins__Enzymes_part_2_.pdf.pdf
Chapter_4__Enzymes_and_Vitamins__Enzymes_part_2_.pdf.pdfChapter_4__Enzymes_and_Vitamins__Enzymes_part_2_.pdf.pdf
Chapter_4__Enzymes_and_Vitamins__Enzymes_part_2_.pdf.pdfRexBlancoNuez
 
05 The Skeletal System - Bone Tissue (1).pdf
05 The Skeletal System - Bone Tissue (1).pdf05 The Skeletal System - Bone Tissue (1).pdf
05 The Skeletal System - Bone Tissue (1).pdfRexBlancoNuez
 
12.0 The Endocrine System.pdf
12.0 The Endocrine System.pdf12.0 The Endocrine System.pdf
12.0 The Endocrine System.pdfRexBlancoNuez
 
07 The Skeletal System - Appendicular Skeleton.pdf
07 The Skeletal System - Appendicular Skeleton.pdf07 The Skeletal System - Appendicular Skeleton.pdf
07 The Skeletal System - Appendicular Skeleton.pdfRexBlancoNuez
 
08 The Skeletal System - Joints (1).pdf
08 The Skeletal System - Joints (1).pdf08 The Skeletal System - Joints (1).pdf
08 The Skeletal System - Joints (1).pdfRexBlancoNuez
 
09 The Muscular System.pdf
09 The Muscular System.pdf09 The Muscular System.pdf
09 The Muscular System.pdfRexBlancoNuez
 

More from RexBlancoNuez (11)

Identifying of Pre-referral Treatment.ppt
Identifying of Pre-referral Treatment.pptIdentifying of Pre-referral Treatment.ppt
Identifying of Pre-referral Treatment.ppt
 
laos police system, president,locationppt.pptx
laos police system, president,locationppt.pptxlaos police system, president,locationppt.pptx
laos police system, president,locationppt.pptx
 
POSITIONING-A-PATIENT-IN-BED.pptx
POSITIONING-A-PATIENT-IN-BED.pptxPOSITIONING-A-PATIENT-IN-BED.pptx
POSITIONING-A-PATIENT-IN-BED.pptx
 
pdfslide.net_-parts-of-the-skeletal-system-bones-skeleton-joints-cartilages.ppt
pdfslide.net_-parts-of-the-skeletal-system-bones-skeleton-joints-cartilages.pptpdfslide.net_-parts-of-the-skeletal-system-bones-skeleton-joints-cartilages.ppt
pdfslide.net_-parts-of-the-skeletal-system-bones-skeleton-joints-cartilages.ppt
 
14.0 The Lymphatic System.pdf
14.0 The Lymphatic System.pdf14.0 The Lymphatic System.pdf
14.0 The Lymphatic System.pdf
 
Chapter_4__Enzymes_and_Vitamins__Enzymes_part_2_.pdf.pdf
Chapter_4__Enzymes_and_Vitamins__Enzymes_part_2_.pdf.pdfChapter_4__Enzymes_and_Vitamins__Enzymes_part_2_.pdf.pdf
Chapter_4__Enzymes_and_Vitamins__Enzymes_part_2_.pdf.pdf
 
05 The Skeletal System - Bone Tissue (1).pdf
05 The Skeletal System - Bone Tissue (1).pdf05 The Skeletal System - Bone Tissue (1).pdf
05 The Skeletal System - Bone Tissue (1).pdf
 
12.0 The Endocrine System.pdf
12.0 The Endocrine System.pdf12.0 The Endocrine System.pdf
12.0 The Endocrine System.pdf
 
07 The Skeletal System - Appendicular Skeleton.pdf
07 The Skeletal System - Appendicular Skeleton.pdf07 The Skeletal System - Appendicular Skeleton.pdf
07 The Skeletal System - Appendicular Skeleton.pdf
 
08 The Skeletal System - Joints (1).pdf
08 The Skeletal System - Joints (1).pdf08 The Skeletal System - Joints (1).pdf
08 The Skeletal System - Joints (1).pdf
 
09 The Muscular System.pdf
09 The Muscular System.pdf09 The Muscular System.pdf
09 The Muscular System.pdf
 

Recently uploaded

AUTONOMIC NERVOUS SYSTEM organization and functions
AUTONOMIC NERVOUS SYSTEM organization and functionsAUTONOMIC NERVOUS SYSTEM organization and functions
AUTONOMIC NERVOUS SYSTEM organization and functionsMedicoseAcademics
 
Microbiology lecture presentation-1.pptx
Microbiology lecture presentation-1.pptxMicrobiology lecture presentation-1.pptx
Microbiology lecture presentation-1.pptxkitati1
 
Adenomyosis or Fibroid- making right diagnosis
Adenomyosis or Fibroid- making right diagnosisAdenomyosis or Fibroid- making right diagnosis
Adenomyosis or Fibroid- making right diagnosisSujoy Dasgupta
 
Physiology of Smooth Muscles -Mechanics of contraction and relaxation
Physiology of Smooth Muscles -Mechanics of contraction and relaxationPhysiology of Smooth Muscles -Mechanics of contraction and relaxation
Physiology of Smooth Muscles -Mechanics of contraction and relaxationMedicoseAcademics
 
Basic structure of hair and hair growth cycle.pptx
Basic structure of hair and hair growth cycle.pptxBasic structure of hair and hair growth cycle.pptx
Basic structure of hair and hair growth cycle.pptxkomalt2001
 
Pharmacokinetic Models by Dr. Ram D. Bawankar.ppt
Pharmacokinetic Models by Dr. Ram D.  Bawankar.pptPharmacokinetic Models by Dr. Ram D.  Bawankar.ppt
Pharmacokinetic Models by Dr. Ram D. Bawankar.pptRamDBawankar1
 
How to cure cirrhosis and chronic hepatitis naturally
How to cure cirrhosis and chronic hepatitis naturallyHow to cure cirrhosis and chronic hepatitis naturally
How to cure cirrhosis and chronic hepatitis naturallyZurück zum Ursprung
 
Moving Forward After Uterine Cancer Treatment: Surveillance Strategies, Testi...
Moving Forward After Uterine Cancer Treatment: Surveillance Strategies, Testi...Moving Forward After Uterine Cancer Treatment: Surveillance Strategies, Testi...
Moving Forward After Uterine Cancer Treatment: Surveillance Strategies, Testi...bkling
 
SGK RỐI LOẠN KALI MÁU CỰC KỲ QUAN TRỌNG.pdf
SGK RỐI LOẠN KALI MÁU CỰC KỲ QUAN TRỌNG.pdfSGK RỐI LOẠN KALI MÁU CỰC KỲ QUAN TRỌNG.pdf
SGK RỐI LOẠN KALI MÁU CỰC KỲ QUAN TRỌNG.pdfHongBiThi1
 
Unit I herbs as raw materials, biodynamic agriculture.ppt
Unit I herbs as raw materials, biodynamic agriculture.pptUnit I herbs as raw materials, biodynamic agriculture.ppt
Unit I herbs as raw materials, biodynamic agriculture.pptPradnya Wadekar
 
blood bank management system project report
blood bank management system project reportblood bank management system project report
blood bank management system project reportNARMADAPETROLEUMGAS
 
Red Blood Cells_anemia & polycythemia.pdf
Red Blood Cells_anemia & polycythemia.pdfRed Blood Cells_anemia & polycythemia.pdf
Red Blood Cells_anemia & polycythemia.pdfMedicoseAcademics
 
FDMA FLAP - The first dorsal metacarpal artery (FDMA) flap is used mainly for...
FDMA FLAP - The first dorsal metacarpal artery (FDMA) flap is used mainly for...FDMA FLAP - The first dorsal metacarpal artery (FDMA) flap is used mainly for...
FDMA FLAP - The first dorsal metacarpal artery (FDMA) flap is used mainly for...Shubhanshu Gaurav
 
QUESTIONS & ANSWERS FOR QUALITY ASSURANCE, RADIATIONBIOLOGY& RADIATION HAZARD...
QUESTIONS & ANSWERS FOR QUALITY ASSURANCE, RADIATIONBIOLOGY& RADIATION HAZARD...QUESTIONS & ANSWERS FOR QUALITY ASSURANCE, RADIATIONBIOLOGY& RADIATION HAZARD...
QUESTIONS & ANSWERS FOR QUALITY ASSURANCE, RADIATIONBIOLOGY& RADIATION HAZARD...Ganesan Yogananthem
 
The Importance of Mental Health: Why is Mental Health Important?
The Importance of Mental Health: Why is Mental Health Important?The Importance of Mental Health: Why is Mental Health Important?
The Importance of Mental Health: Why is Mental Health Important?Ryan Addison
 
"Radical excision of DIE in subferile women with deep infiltrating endometrio...
"Radical excision of DIE in subferile women with deep infiltrating endometrio..."Radical excision of DIE in subferile women with deep infiltrating endometrio...
"Radical excision of DIE in subferile women with deep infiltrating endometrio...Sujoy Dasgupta
 
Physiotherapy Management of Rheumatoid Arthritis
Physiotherapy Management of Rheumatoid ArthritisPhysiotherapy Management of Rheumatoid Arthritis
Physiotherapy Management of Rheumatoid ArthritisNilofarRasheed1
 
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.Bulimia nervosa ( Eating Disorders) Mental Health Nursing.
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.aarjukhadka22
 
concept of total quality management (TQM).
concept of total quality management (TQM).concept of total quality management (TQM).
concept of total quality management (TQM).kishan singh tomar
 
Male Infertility Panel Discussion by Dr Sujoy Dasgupta
Male Infertility Panel Discussion by Dr Sujoy DasguptaMale Infertility Panel Discussion by Dr Sujoy Dasgupta
Male Infertility Panel Discussion by Dr Sujoy DasguptaSujoy Dasgupta
 

Recently uploaded (20)

AUTONOMIC NERVOUS SYSTEM organization and functions
AUTONOMIC NERVOUS SYSTEM organization and functionsAUTONOMIC NERVOUS SYSTEM organization and functions
AUTONOMIC NERVOUS SYSTEM organization and functions
 
Microbiology lecture presentation-1.pptx
Microbiology lecture presentation-1.pptxMicrobiology lecture presentation-1.pptx
Microbiology lecture presentation-1.pptx
 
Adenomyosis or Fibroid- making right diagnosis
Adenomyosis or Fibroid- making right diagnosisAdenomyosis or Fibroid- making right diagnosis
Adenomyosis or Fibroid- making right diagnosis
 
Physiology of Smooth Muscles -Mechanics of contraction and relaxation
Physiology of Smooth Muscles -Mechanics of contraction and relaxationPhysiology of Smooth Muscles -Mechanics of contraction and relaxation
Physiology of Smooth Muscles -Mechanics of contraction and relaxation
 
Basic structure of hair and hair growth cycle.pptx
Basic structure of hair and hair growth cycle.pptxBasic structure of hair and hair growth cycle.pptx
Basic structure of hair and hair growth cycle.pptx
 
Pharmacokinetic Models by Dr. Ram D. Bawankar.ppt
Pharmacokinetic Models by Dr. Ram D.  Bawankar.pptPharmacokinetic Models by Dr. Ram D.  Bawankar.ppt
Pharmacokinetic Models by Dr. Ram D. Bawankar.ppt
 
How to cure cirrhosis and chronic hepatitis naturally
How to cure cirrhosis and chronic hepatitis naturallyHow to cure cirrhosis and chronic hepatitis naturally
How to cure cirrhosis and chronic hepatitis naturally
 
Moving Forward After Uterine Cancer Treatment: Surveillance Strategies, Testi...
Moving Forward After Uterine Cancer Treatment: Surveillance Strategies, Testi...Moving Forward After Uterine Cancer Treatment: Surveillance Strategies, Testi...
Moving Forward After Uterine Cancer Treatment: Surveillance Strategies, Testi...
 
SGK RỐI LOẠN KALI MÁU CỰC KỲ QUAN TRỌNG.pdf
SGK RỐI LOẠN KALI MÁU CỰC KỲ QUAN TRỌNG.pdfSGK RỐI LOẠN KALI MÁU CỰC KỲ QUAN TRỌNG.pdf
SGK RỐI LOẠN KALI MÁU CỰC KỲ QUAN TRỌNG.pdf
 
Unit I herbs as raw materials, biodynamic agriculture.ppt
Unit I herbs as raw materials, biodynamic agriculture.pptUnit I herbs as raw materials, biodynamic agriculture.ppt
Unit I herbs as raw materials, biodynamic agriculture.ppt
 
blood bank management system project report
blood bank management system project reportblood bank management system project report
blood bank management system project report
 
Red Blood Cells_anemia & polycythemia.pdf
Red Blood Cells_anemia & polycythemia.pdfRed Blood Cells_anemia & polycythemia.pdf
Red Blood Cells_anemia & polycythemia.pdf
 
FDMA FLAP - The first dorsal metacarpal artery (FDMA) flap is used mainly for...
FDMA FLAP - The first dorsal metacarpal artery (FDMA) flap is used mainly for...FDMA FLAP - The first dorsal metacarpal artery (FDMA) flap is used mainly for...
FDMA FLAP - The first dorsal metacarpal artery (FDMA) flap is used mainly for...
 
QUESTIONS & ANSWERS FOR QUALITY ASSURANCE, RADIATIONBIOLOGY& RADIATION HAZARD...
QUESTIONS & ANSWERS FOR QUALITY ASSURANCE, RADIATIONBIOLOGY& RADIATION HAZARD...QUESTIONS & ANSWERS FOR QUALITY ASSURANCE, RADIATIONBIOLOGY& RADIATION HAZARD...
QUESTIONS & ANSWERS FOR QUALITY ASSURANCE, RADIATIONBIOLOGY& RADIATION HAZARD...
 
The Importance of Mental Health: Why is Mental Health Important?
The Importance of Mental Health: Why is Mental Health Important?The Importance of Mental Health: Why is Mental Health Important?
The Importance of Mental Health: Why is Mental Health Important?
 
"Radical excision of DIE in subferile women with deep infiltrating endometrio...
"Radical excision of DIE in subferile women with deep infiltrating endometrio..."Radical excision of DIE in subferile women with deep infiltrating endometrio...
"Radical excision of DIE in subferile women with deep infiltrating endometrio...
 
Physiotherapy Management of Rheumatoid Arthritis
Physiotherapy Management of Rheumatoid ArthritisPhysiotherapy Management of Rheumatoid Arthritis
Physiotherapy Management of Rheumatoid Arthritis
 
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.Bulimia nervosa ( Eating Disorders) Mental Health Nursing.
Bulimia nervosa ( Eating Disorders) Mental Health Nursing.
 
concept of total quality management (TQM).
concept of total quality management (TQM).concept of total quality management (TQM).
concept of total quality management (TQM).
 
Male Infertility Panel Discussion by Dr Sujoy Dasgupta
Male Infertility Panel Discussion by Dr Sujoy DasguptaMale Infertility Panel Discussion by Dr Sujoy Dasgupta
Male Infertility Panel Discussion by Dr Sujoy Dasgupta
 

Protein-Metabolism.pptx

  • 1. Protein Digestion and Absorption Return to TOC Section 26.1 Copyright ©2016 Cengage Learning. All Rights Reserved. 1
  • 2. Chapter 26 Chapter Outline Copyright ©2016 Cengage Learning. All Rights Reserved. 2 26.1 Protein digestion and absorption 26.2 Amino acid utilization 26.3 Transamination and oxidative deamination 26.4 The urea cycle 26.5 Amino acid carbon skeletons 26.6 Amino acid biosynthesis 26.7 Hemoglobin catabolism 26.8 Proteins and the element sulfur 26.9 Interrelationships among metabolic pathways 26.10 B vitamins and protein metabolism
  • 3. Protein Digestion and Absorption Return to TOC Section 26.1 Copyright ©2016 Cengage Learning. All Rights Reserved. 3 • Protein digestion starts in the stomach – Dietary protein present in the stomach stimulates the release of gastrin • Gastrin promotes secretion of pepsinogen and HCl – HCl in the stomach has 3 functions • Antiseptic properties kill most bacteria • Denaturing action “unwinds” globular properties • Acidic property leads to activation of pepsinogen – Pepsin affects the hydrolysis of 10% peptide bonds
  • 4. Protein Digestion and Absorption Return to TOC Section 26.1 Copyright ©2016 Cengage Learning. All Rights Reserved. 4 • Production of secretin is stimulated by the passage of small amounts of acidic protein content into the small intestine • Secretin stimulates bicarbonate (HCO3 -) production, which in turn helps neutralize acidified gastric content – Promotes secretion of pancreatic digestive enzymes trypsin, chymotrypsin, and carboxypeptidase in their inactive forms
  • 5. Protein Digestion and Absorption Return to TOC Section 26.1 Protein Digestive Enzymes in the Intestine • Proteolytic enzymes – Enzymes that attack peptide bonds – Pepsin – Trypsin – Chymotrypsin • Zymogens – Proteolytic enzymes produced in inactive form Copyright ©2016 Cengage Learning. All Rights Reserved. 5
  • 6. Protein Digestion and Absorption Return to TOC Section 26.1 Copyright ©2016 Cengage Learning. All Rights Reserved. 6 • Liberated amino acids are transported into the bloodstream via active transport process • The passage of polypeptides and small proteins across the intestinal wall is uncommon in adults – In infants, the transport of polypeptides allows the passage of proteins such as antibodies in colostrum milk from a mother to a nursing infant to build up immunologic protection in the infant
  • 7. Protein Digestion and Absorption Return to TOC Section 26.1 Figure 26.1 - Digestion of Protein in Humans Copyright ©2016 Cengage Learning. All Rights Reserved. 7
  • 8. Protein Digestion and Absorption Return to TOC Section 26.1 Protein digestion begins in the _____ and is completed in the _____, resulting in the release of amino acids. a. mouth; stomach b. mouth; small intestine c. stomach; small intestine d. small intestine; liver Copyright ©2016 Cengage Learning. All Rights Reserved. 8
  • 9. Protein Digestion and Absorption Return to TOC Section 26.1 Protein digestion begins in the _____ and is completed in the _____, resulting in the release of amino acids. a. mouth; stomach b. mouth; small intestine c. stomach; small intestine d. small intestine; liver Copyright ©2016 Cengage Learning. All Rights Reserved. 9
  • 10. Section 26.2 Amino Acid Utilization Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 10 Amino Acid Pool • Amino acids formed through digestion process enter the amino acid pool in the body • Amino acid pool: The total supply of free amino acids available for use in the human body • Sources – Dietary protein – Protein turnover: The repetitive process in which proteins are degraded and resynthesized – Biosynthesis of amino acids in the liver – Only nonessential amino acids are synthesized
  • 11. Section 26.2 Amino Acid Utilization Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 11 Nitrogen Balance • The state that results when the amount of nitrogen taken into the human body as protein equals the amount of nitrogen excreted from the body in waste materials • Types of nitrogen imbalance – Negative nitrogen imbalance - Protein degradation exceeds protein synthesis • Amount of nitrogen in urine exceeds consumed amount • Results in tissue wasting – Positive nitrogen imbalance - Rate of protein synthesis (anabolism) is more than protein degradation (catabolism) • Indicated by the synthesis of large amounts of tissue
  • 12. Section 26.2 Amino Acid Utilization Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 12 Uses of Amino Acids in the Human Body • Protein synthesis ‒ Uses approximately 75% of free amino acids • Synthesis of non-protein nitrogen-containing compounds ‒ Synthesis of purines and pyrimidines ‒ Synthesis of heme for hemoglobin • Synthesis of nonessential amino acids ‒ Essential amino acids cannot be synthesized due to the lack of an appropriate carbon chain • Production of energy ‒ Amino acids are not stored in the body • Excesses are degraded • Each amino acid has a unique degradation pathway
  • 13. Section 26.2 Amino Acid Utilization Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 13 Degradation Pathways • The amino nitrogen atom is removed and excreted from the body as urea • The remaining carbon skeleton is converted to pyruvate, acetyl CoA, or a citric acid cycle intermediate
  • 14. Section 26.2 Amino Acid Utilization Return to TOC Amino acids produced during protein digestion enter the _____ of the body. a. energy production pool b. amino acid pool c. protein synthesis pool d. nitrogen balance pool Copyright ©2016 Cengage Learning. All Rights Reserved. 14
  • 15. Section 26.2 Amino Acid Utilization Return to TOC Amino acids produced during protein digestion enter the _____ of the body. a. energy production pool b. amino acid pool c. protein synthesis pool d. nitrogen balance pool Copyright ©2016 Cengage Learning. All Rights Reserved. 15
  • 16. Section 26.3 Transamination and Oxidative Deamination Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 16 • Degradation of an amino acid takes place in two stages ̶ Removal of the α-amino group ̶ Degradation of the remaining carbon skeleton • Removal of amino groups requires: – Transamination: A biochemical reaction characterized by the interchange of the amino group in an α-amino acid with the keto group in an α-keto acid – Oxidative deamination
  • 17. Section 26.3 Transamination and Oxidative Deamination Return to TOC Glutamate Production via Transamination • Glutamate is produced through transamination when α- ketoglutarate is the amino group acceptor Copyright ©2016 Cengage Learning. All Rights Reserved. 17
  • 18. Section 26.3 Transamination and Oxidative Deamination Return to TOC Aspartate Production via Transamination • This occurs when glutamate is the reacting acid and oxaloacetate is the reacting keto acid Copyright ©2016 Cengage Learning. All Rights Reserved. 18
  • 19. Section 26.3 Transamination and Oxidative Deamination Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 19 Ammonium Production via Oxidative Deamination • Oxidative deamination is a biochemical reaction in which an α-amino acid is converted to an α-keto acid with release of an ammonium ion – Occurs in the mitochondria of the liver and kidney
  • 20. Section 26.3 Transamination and Oxidative Deamination Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 20 Practice Exercise Indicate whether each of the following reaction characteristics is associated with the process of transamination or with the process of oxidative deamination: a. One of the reactants is a keto acid and one of the products is a keto acid. b. Enzymes with a specificity toward α-ketoglutarate are often active. c. NAD is used as an oxidizing agent. d. An aminotransferase enzyme is active.
  • 21. Section 26.3 Transamination and Oxidative Deamination Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 21 Practice Exercise Indicate whether each of the following reaction characteristics is associated with the process of transamination or with the process of oxidative deamination: a. One of the reactants is a keto acid and one of the products is a keto acid. b. Enzymes with a specificity toward α-ketoglutarate are often active. c. NAD is used as an oxidizing agent. d. An aminotransferase enzyme is active. Answers: a. Transamination b. Transamination c. Oxidative deamination d. Transamination
  • 22. Section 26.3 Transamination and Oxidative Deamination Return to TOC What two types of biochemical reactions are required for the removal of the amino group from most amino acids? a. Amination and reductive deamination b. Amination and oxidative deamination c. Transamination and reductive deamination d. Transamination and oxidative deamination Copyright ©2016 Cengage Learning. All Rights Reserved. 22
  • 23. Section 26.3 Transamination and Oxidative Deamination Return to TOC What two types of biochemical reactions are required for the removal of the amino group from most amino acids? a. Amination and reductive deamination b. Amination and oxidative deamination c. Transamination and reductive deamination d. Transamination and oxidative deamination Copyright ©2016 Cengage Learning. All Rights Reserved. 23
  • 24. Section 26.4 The Urea Cycle Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 24 • The net effect of transamination and deamination reactions is the production of ammonium ions and aspartate • Urea cycle: A series of biochemical reactions in which urea is produced from ammonium ions and aspartate as nitrogen sources • Urea produced in the liver is transported via blood to the kidneys and eliminated from the body in urine • Urea is an odorless white solid with a salty taste, has a melting point of 133oC, and is soluble in water
  • 25. Section 26.4 The Urea Cycle Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 25 Carbamoyl Phosphate • One of the sources of fuel for the urea cycle • Two ATP molecules are expended in the formation of one carbamoyl phosphate molecule • It contains a high-energy phosphate bond • It is formed in the mitochondrial matrix
  • 26. Section 26.4 The Urea Cycle Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 26 Steps of the Urea Cycle • Stage 1 - Carbamoyl group transfer – The carbamoyl group of carbamoyl phosphate is transferred to ornithine to form citrulline • Stage 2 - Citrulline–aspartate condensation – Citrulline is transported into the cytosol and reacts with aspartate to produce argininosuccinate synthetase, utilizing ATP • Stage 3 - Argininosuccinate cleavage – Argininosuccinate is cleaved to arginine and fumarate by the enzyme argininosuccinate lyase
  • 27. Section 26.4 The Urea Cycle Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 27 Steps of the Urea Cycle • Stage 4 - Urea from arginine hydrolysis – Hydrolysis of arginine produces urea and regenerates ornithine under the influence of arginase – The oxygen atom present in urea comes from water – Ornithine is transported back to mitochondria to be used in the urea cycle
  • 28. Section 26.4 The Urea Cycle Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 28 Urea Cycle Net Reaction • The equivalent of four ATP molecules is expended in the production of one urea molecule – Two molecules of ATP are consumed in the production of carbamoyl phosphate – The equivalent of two ATP molecules is consumed in step two of the urea cycle to give AMP and the PPi
  • 29. Section 26.4 The Urea Cycle Return to TOC Figure 26.6 - Conversion of Carbamoyl Phosphate to Urea Copyright ©2016 Cengage Learning. All Rights Reserved. 29
  • 30. Section 26.4 The Urea Cycle Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 30 Linkage Between the Urea and Citric Acid Cycles • Fumarate produced is ultimately converted to asparte • Aspartate re-enters the urea cycle at step two
  • 31. Section 26.4 The Urea Cycle Return to TOC The net effect of amino acid degradation is the production of the ammonium ion, which is toxic. How is the ammonium ion eliminated from the body? a. It is biosynthesized for the production of nonessential amino acids. b. It is recycled in the production of amino acids. c. It is converted to urea in the urea cycle and excreted in the urine. d. Both (b) and (c). Copyright ©2016 Cengage Learning. All Rights Reserved. 31
  • 32. Section 26.4 The Urea Cycle Return to TOC The net effect of amino acid degradation is the production of the ammonium ion, which is toxic. How is the ammonium ion eliminated from the body? a. It is biosynthesized for the production of nonessential amino acids. b. It is recycled in the production of amino acids. c. It is converted to urea in the urea cycle and excreted in the urine. d. Both (b) and (c). Copyright ©2016 Cengage Learning. All Rights Reserved. 32
  • 33. Section 26.5 Amino Acid Carbon Skeletons Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 33 • Transamination/oxidative deamination removes the amino group from an amino acid – An α-keto acid that contains the skeleton of the amino acid is produced • Each of the 20 amino acids undergo a different degradation process – Products formed are among a group of seven intermediates • Four products are intermediates in the citric acid cycle • Three products are pyruvate, acetyl CoA, and acetoacetyl CoA
  • 34. Section 26.5 Amino Acid Carbon Skeletons Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 34 • The amino acids converted to citric acid cycle intermediates can serve as glucose precursors – Glucogenic amino acid: An amino acid that has a carbon-containing degradation product that can be used to produce glucose via gluconeogenesis • The amino acids converted to acetyl CoA or acetoacetyl CoA can contribute to the formation of fatty acids – Ketogenic amino acid: An amino acid that has a carbon- containing degradation product that can be used to produce ketone bodies
  • 35. Section 26.5 Amino Acid Carbon Skeletons Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 35 Figure 26.9 - Fates of Carbon Skeletons of Amino Acids
  • 36. Section 26.5 Amino Acid Carbon Skeletons Return to TOC What are the four intermediates that contain the carbon skeletons from amino acid degradation in the citric acid cycle? a. Citric acid, α-ketoglutarate, acetyl CoA, and fumarate b. α-Ketoglutarate, succinyl CoA, fumarate, and oxaloacetate c. α-Ketoglutarate, acetyl CoA, succinyl CoA, and fumarate d. Citric acid, succinyl CoA, fumarate, and oxaloacetate Copyright ©2016 Cengage Learning. All Rights Reserved. 36
  • 37. Section 26.5 Amino Acid Carbon Skeletons Return to TOC What are the four intermediates that contain the carbon skeletons from amino acid degradation in the citric acid cycle? a. Citric acid, α-ketoglutarate, acetyl CoA, and fumarate b. α-Ketoglutarate, succinyl CoA, fumarate, and oxaloacetate c. α-Ketoglutarate, acetyl CoA, succinyl CoA, and fumarate d. Citric acid, succinyl CoA, fumarate, and oxaloacetate Copyright ©2016 Cengage Learning. All Rights Reserved. 37
  • 38. Section 26.6 Amino Acid Biosynthesis Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 38 • Nonessential amino acids are synthesized in fewer steps than essential amino acids • The primary source of essential amino acids for humans and animals is plants
  • 39. Section 26.6 Amino Acid Biosynthesis Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 39 Figure 26.10 - Summary of the Starting Materials for the Biosynthesis of the 11 Nonessential Amino Acids
  • 40. Section 26.6 Amino Acid Biosynthesis Return to TOC Which of the following statements is/are true of amino acids? a. Nonessential amino acids are synthesized in fewer steps than essential amino acids. b. Most bacteria and plants synthesize all amino acids via pathways that are not present in humans. c. Plants are the major source of the essential amino acids in humans and animals. d. All the above. Copyright ©2016 Cengage Learning. All Rights Reserved. 40
  • 41. Section 26.6 Amino Acid Biosynthesis Return to TOC Which of the following statements is/are true of amino acids? a. Nonessential amino acids are synthesized in fewer steps than essential amino acids. b. Most bacteria and plants synthesize all amino acids via pathways that are not present in humans. c. Plants are the major source of the essential amino acids in humans and animals. d. All the above. Copyright ©2016 Cengage Learning. All Rights Reserved. 41
  • 42. Section 26.7 Hemoglobin Catabolism Return to TOC Red Blood Cells • They are highly specialized cells whose primary function is to deliver oxygen to cells and remove carbon dioxide from body tissues • Mature red blood cells have no nucleus or DNA – Filled with hemoglobin • Red blood cells are formed in the bone marrow – Approximately 200 billion new red blood cells are formed daily • The life span of a red blood cell is approximately four months Copyright ©2016 Cengage Learning. All Rights Reserved. 42
  • 43. Section 26.7 Hemoglobin Catabolism Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 43 • Hemoglobin is a conjugated protein with two components – Globin - The protein portion – Heme - The prosthetic group • Iron atom present in heme interacts with oxygen – A reversible complex is formed
  • 44. Section 26.7 Hemoglobin Catabolism Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 44 • Old RBCs are broken down in the spleen and liver • Degradation of hemoglobin – Globin protein part is converted to amino acids, which become part of the amino acid pool – The iron atom becomes part of ferritin • An iron-storage protein – The tetrapyrrole carbon arrangement of heme is degraded to bile pigments • Eliminated in feces or urine
  • 45. Section 26.7 Hemoglobin Catabolism Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 45 Bile Pigments • Colored tetrapyrrole degradation products present in bile • Types of bile pigments – Biliverdin - Green in color – Bilirubin - Reddish orange in color – Stercobilin - Brownish in color – Urobilin - Yellow in color
  • 46. Section 26.7 Hemoglobin Catabolism Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 46 Bile Pigments • Daily normal excretion of bile pigments – 1–2 mg in urine – 250–350 mg in feces • Jaundice – Caused by an imbalance between the formation and removal of bilirubin – Gives the skin and white of the eye the characteristic yellow tint of the illness
  • 47. Section 26.7 Hemoglobin Catabolism Return to TOC Degradation of heme from hemolysis produces the product _____, which is converted to _____. a. bilirubin; biliverdin b. biliverdin; bilirubin c. bilirubin; urobilin d. stercobilin; urobilin Copyright ©2016 Cengage Learning. All Rights Reserved. 47
  • 48. Section 26.7 Hemoglobin Catabolism Return to TOC Degradation of heme from hemolysis produces the product _____, which is converted to _____. a. bilirubin; biliverdin b. biliverdin; bilirubin c. bilirubin; urobilin d. stercobilin; urobilin Copyright ©2016 Cengage Learning. All Rights Reserved. 48
  • 49. Section 26.8 Proteins and the Element Sulfur Return to TOC Biodegradation of Cysteine • Occurs in two steps – A transamination reaction – Release of —SH Copyright ©2016 Cengage Learning. All Rights Reserved. 49
  • 50. Section 26.8 Proteins and the Element Sulfur Return to TOC Biosynthesis of Cysteine • Serine is the precursor • Serine is converted to cysteine in two steps – Activation of serine by an acetyl CoA molecule – Sulfhydration with hydrogen sulphide • Hydrogen sulphide is produced by sulfate assimilation Copyright ©2016 Cengage Learning. All Rights Reserved. 50
  • 51. Section 26.8 Proteins and the Element Sulfur Return to TOC Figure 26.13 (a) - Steps 1 and 2 of Sulfate Assimilation Copyright ©2016 Cengage Learning. All Rights Reserved. 51
  • 52. Section 26.8 Proteins and the Element Sulfur Return to TOC Figure 26.13 (b) - Steps 3 and 4 of Sulfate Assimilation Copyright ©2016 Cengage Learning. All Rights Reserved. 52
  • 53. Section 26.8 Proteins and the Element Sulfur Return to TOC Hydrogen Sulfide as a Biochemical Signalling Agent Copyright ©2016 Cengage Learning. All Rights Reserved. 53 • It regulates vascular blood flow and blood pressure – Acts as a smooth muscle relaxant and vasodilator • It influences brain function – Brain levels of H2S are lower than normal in cases of Alzheimer’s disease • It influences insulin levels in type I diabetes – Excess of H2S leads to reduced insulin production
  • 54. Section 26.8 Proteins and the Element Sulfur Return to TOC In degradation of the sulfur-containing amino acid cysteine, the sulfur is released in the form of: a. hydrogen sulfide. b. sulfate ion. c. sulfur dioxide. d. none of the above. Copyright ©2016 Cengage Learning. All Rights Reserved. 54
  • 55. Section 26.8 Proteins and the Element Sulfur Return to TOC In degradation of the sulfur-containing amino acid cysteine, the sulfur is released in the form of: a. hydrogen sulfide. b. sulfate ion. c. sulfur dioxide. d. none of the above. Copyright ©2016 Cengage Learning. All Rights Reserved. 55
  • 56. Section 26.9 Interrelationships Among Metabolic Pathways Return to TOC • The metabolic pathways of carbohydrates, lipids, and proteins are integrally linked to one another − A change in one pathway can affect many other pathways • Examples − Feasting - Over-eating − Causes the body to store a limited amount as glycogen and the rest as fat − Fasting - Food is not ingested − The body uses its stored glycogen and fat for energy − Starvation - Prolonged fasting − Body protein is broken down to amino acids to synthesize glucose Copyright ©2016 Cengage Learning. All Rights Reserved. 56
  • 57. Section 26.9 Interrelationships Among Metabolic Pathways Return to TOC During starvation, what is used as a source of energy after the glycogen stores have been depleted? a. Amino acids of degraded proteins which are used to synthesize glucose b. Body fats which are converted to ketone bodies and used as a source of brain energy c. Glycogen stores are never depleted d. Both (a) and (b) Copyright ©2016 Cengage Learning. All Rights Reserved. 57
  • 58. Section 26.9 Interrelationships Among Metabolic Pathways Return to TOC During starvation, what is used as a source of energy after the glycogen stores have been depleted? a. Amino acids of degraded proteins which are used to synthesize glucose b. Body fats which are converted to ketone bodies and used as a source of brain energy c. Glycogen stores are never depleted d. Both (a) and (b) Copyright ©2016 Cengage Learning. All Rights Reserved. 58
  • 59. Section 26.10 B Vitamins and Protein Metabolism Return to TOC • All eight B vitamins participate in various pathways of protein metabolism – Niacin • Oxidative deamination reactions – PLP • Transamination reactions Copyright ©2016 Cengage Learning. All Rights Reserved. 59
  • 60. Section 26.10 B Vitamins and Protein Metabolism Return to TOC Figure 26.15 - Involvement of B Vitamins in Protein Metabolism Copyright ©2016 Cengage Learning. All Rights Reserved. 60
  • 61. Section 26.10 B Vitamins and Protein Metabolism Return to TOC Transamination reactions require the cofactor PLP, which involves: a. folate. b. riboflavin. c. vitamin B6. d. none of the above. Copyright ©2016 Cengage Learning. All Rights Reserved. 61
  • 62. Section 26.10 B Vitamins and Protein Metabolism Return to TOC Transamination reactions require the cofactor PLP, which involves: a. folate. b. riboflavin. c. vitamin B6. d. none of the above. Copyright ©2016 Cengage Learning. All Rights Reserved. 62
  • 63. Chapter 26 What best describes what happens to the protein after eating a high-protein meal? a. Protein digestion begins in the stomach and then moves to the small intestine where complete digestion occurs. The free amino acids are stored in the amino acid pool. b. Proteins are denatured in the stomach and are then moved to the small intestine for complete digestion. c. Protein digestion begins in the mouth and then moves to the stomach for complete digestion by the enzyme pepsin. The free amino acids are then moved to the small intestine and stored in the amino acid pool. d. Protein digestion begins in the mouth, is continued in the stomach, and is completed in the small intestine. Copyright ©2016 Cengage Learning. All Rights Reserved. 63
  • 64. Chapter 26 What best describes what happens to the protein after eating a high-protein meal? a. Protein digestion begins in the stomach and then moves to the small intestine where complete digestion occurs. The free amino acids are stored in the amino acid pool. b. Proteins are denatured in the stomach and are then moved to the small intestine for complete digestion. c. Protein digestion begins in the mouth and then moves to the stomach for complete digestion by the enzyme pepsin. The free amino acids are then moved to the small intestine and stored in the amino acid pool. d. Protein digestion begins in the mouth, is continued in the stomach, and is completed in the small intestine. Copyright ©2016 Cengage Learning. All Rights Reserved. 64
  • 65. Chapter 26 In the early 1990s, nitric oxide (NO) was discovered in the body as a gaseous chemical messenger. What effect does nitric oxide have in the body? a. It stimulates the urea cycle to ensure proper functioning in the removal of the toxic ammonium ion. b. It plays a part in maintaining blood pressure and is found in the brain where it may play a part in long-term memory. c. It is rapidly converted to an amino group which is used in amino acid synthesis. d. It carries messages into the mitochondria to signal the production of large amounts of energy when called for by the hormone epinephrine. Copyright ©2016 Cengage Learning. All Rights Reserved. 65
  • 66. Chapter 26 In the early 1990s, nitric oxide (NO) was discovered in the body as a gaseous chemical messenger. What effect does nitric oxide have in the body? a. It stimulates the urea cycle to ensure proper functioning in the removal of the toxic ammonium ion. b. It plays a part in maintaining blood pressure and is found in the brain where it may play a part in long-term memory. c. It is rapidly converted to an amino group which is used in amino acid synthesis. d. It carries messages into the mitochondria to signal the production of large amounts of energy when called for by the hormone epinephrine. Copyright ©2016 Cengage Learning. All Rights Reserved. 66