3. Biochemistry
- Biochemistry is the study of the chemistry of cells and
organisms.
- It is concerned with the types of molecules found in biological
systems, their structure, and their chemical properties.
- Biochemistry also deals with the function of these molecules,
how they interact, and what reactions they undergo
4. Properties of Biomolecules
A. General Properties
- Biomolecules are organic molecules, not fundamentally different
from other, typical organic molecules. They are the same types of
molecules, react in the same ways, and obey the same physical
laws.
B. Composition and Structure
- Biomolecules contain mainly carbon, which behaves as it always
does in organic compounds, forming 4 bonds, usually with a
tetrahedral arrangement.
- The carbon skeleton can be linear, branched, cyclic, or aromatic.
Other important elements are H, O, N, P and S.
- A bout 30 elements are required by biological systems, including
iodine and many metals, though most of these are needed in only
trace amounts.
5. Properties of Biomolecules
- The atoms of a biomolecule are arranged in space in a precise
way, and proper arrangement is usually needed for proper
function.
- The 3-dimensional shape is maintained by numerous non-
covalent bonds between atoms in the molecule.
- Because of the weak nature of most noncovalent bonds and
because of interactions between the biomolecule and the solvent,
the biomolecule’s structure is flexible rather than static.
6. Biomolecules
- Organic molecule = contains carbon (C)
- Biomolecule = organic molecule associated with living
organisms
4 Major Groups of Biomolecules
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleotides
7.
8. Characteristic of Biomolecules
- Most of the molecules of concern have 3 elements in
common C, H and O
- Also many biological molecules contain P and N
- Each group has a characteristic composition and
molecular structure
- Many are polymers- large molecules of repeating units
9.
10. Functional Groups
- Functional groups are an combinations of atoms that
tend to move from molecule to molecule as a single
unit
- Several functional groups are found repeatedly in
biomolecules
- OH is a hydroxyl group- tends to be added and
removed from molecules as a group rather than as
single H or O atoms
- Functional Groups tend to attach to molecules via a
single covalent bond
11.
12.
13. Carbohydrates
- Carbohydrates (carbon with water)
- Most abundant biomolecules
- General formula is (CH2O)n (carbon and water) n=
number of repetitions of the carbohydrate unit in the
molecule
To write the formula- multiply each subscript by n
- E.g.; glucose has 6 units C6H12O6
14. Carbohydrates
- Carbohydrates (sugars & starches)
- The smallest carbohydrates are the monosaccharides
with molecular weights of around 100-200.
- They are a major source of energy for biological
systems.
- Polysaccharides are polymers of monosaccharides with
molecular weights often in the millions.
- Polysaccharides also have definite shapes and serve as
structural elements or as stored metabolic energy
18. Carbohydrates
- Mono or disaccharides = simple sugars
- Have suffix –ose at end of names
- The most common monosaccharides are the building
blocks for the complex carbohydrates
- Polysaccharides = complex polymers of glucose
- Glucose is stored in the body for energy as a
polysaccharide called glycogen, plants store it as starch
19. Carbohydrates
- The major function of carbohydrates in the body is to
provide cells with energy in chemical reactions (i.e. as a
fuel). They consist of carbon, hydrogen, and oxygen
atom
- 1 gram of carbohydrates releases 4.2 kcal of energy
when oxidized in the body. They are a major food
source and a key form of energy for most organisms.
- Sources of carbohydrate include whole grains, fruit,
and vegetables. Carbohydrates, also known as
saccharides or carbs, are sugars or starches.
20. Carbohydrates
- The major function of carbohydrates in the body is to
provide cells with energy in chemical reactions (i.e. as a
fuel). They consist of carbon, hydrogen, and oxygen
atom
- 1 gram of carbohydrates releases 4.2 kcal of energy
when oxidized in the body. They are a major food
source and a key form of energy for most organisms.
- Sources of carbohydrate include whole grains, fruit,
and vegetables. Carbohydrates, also known as
saccharides or carbs, are sugars or starches.
21.
22. The Structure of Simple Sugars
- Each sugar molecule consists of a backbone of
carbon atoms linked together in a linear array by
single bonds.
- Each of the carbon atoms of the backbone is linked to
a single hydroxyl group, except for one that bears a
carbonyl (C= O) group.
- If the carbonyl group is located at an internal position
(to form a ketone group), the sugar is a ketose, such as
fructose
28. Complex carbohydrates
- Complex carbohydrates are polymers of the simple sugars. In
other words, the complex carbohydrates are long chains of
simple sugar units bonded together (for this reason the complex
carbohydrates are often referred to as polysaccharides).
- Starch is the principal polysaccharide used by plants to store
glucose for later use as energy. Plants often store starch in seeds
or other specialized organs; for example, common sources of
starch include rice, beans, wheat, corn, potatoes, and so on..
29. Complex carbohydrates
- When humans eat starch, an enzyme that occurs in saliva and in
the intestines called amylase breaks the bonds between the
repeating glucose units, thus allowing the sugar to be absorbed
into the bloodstream.
- Once absorbed into the bloodstream, the human body distributes
glucose to the areas where it is needed for energy or stores it as
its own special polymer – glycogen.
30.
31.
32. Complex carbohydrates
- Glycogen, another polymer of glucose, is the polysaccharide used
by animals to store energy.
- Excess glucose is bonded together to form glycogen molecules,
which the animal stores in the liver and muscle tissue as an
"instant" source of energy.
- Both starch and glycogen are polymers of glucose; however,
starch is a long, straight chain of glucose units, whereas glycogen
is a branched chain of glucose unit
33. Complex carbohydrates
- Another important polysaccharide is cellulose. Cellulose is yet a
third polymer of the monosaccharide glucose.
- Cellulose differs from starch and glycogen because the glucose
units form a two-dimensional structure, with hydrogen bonds
holding together nearby polymers, thus giving the molecule added
stability
- Cellulose, also known as plant fiber, cannot be digested by human
beings, therefore cellulose passes through the digestive tract
without being absorbed into the body
- Despite the fact that it cannot be used as an energy source in most
animals, cellulose fiber is essential in the diet because it helps
exercise the digestive track and keep it clean and healthy.
34.
35. Complex carbohydrates
- Another important polysaccharide is cellulose. Cellulose is yet a
third polymer of the monosaccharide glucose.
- Cellulose differs from starch and glycogen because the glucose
units form a two-dimensional structure, with hydrogen bonds
holding together nearby polymers, thus giving the molecule added
stability
- Cellulose, also known as plant fiber, cannot be digested by human
beings, therefore cellulose passes through the digestive tract
without being absorbed into the body
- Despite the fact that it cannot be used as an energy source in most
animals, cellulose fiber is essential in the diet because it helps
exercise the digestive track and keep it clean and healthy.
36. Counting Carbohydrates
- Counting carbohydrates provides a total amount of daily
carbohydrates and helps clarify how each type of carbohydrate
(starches, dairy products, starchy and non-starchy vegetables,
sweets, desserts and other carbohydrates) affects blood glucose.
- The amounts and types of each of these carbohydrates can be
adjusted at each meal and snack as needed.
- In carbohydrate counting, carbohydrates are first calculated as a
percentage of total calories and then in calories and grams. About
one-half (50 percent) of total calories should come from
carbohydrates.
- On a 2,200-calorie diet, 50 percent of total calories equals about
1,100 calories (2,200 calories × .50 = 1,100 calories).
37. Counting Carbohydrates
- Since there are 4 calories per gram of carbohydrate, this
amounts to 275 grams (1,100 calories/4 = 275 grams). This is the
total amount of daily carbohydrates.
- One could then divide this amount into three meals (275 grams/3
= 92 grams of carbohydrates/meal) or five meals and snacks
(275 grams/5 = 55 grams of carbohydrates/meal or snack).
38. Carbohydrates as Food
- Carbohydrate is essential for the survival of some tissues and as a
structural constituent of nucleic acids, glycoproteins,
proteoglycans, and glycolipids.
- The normal adult can synthesize all the needed carbohydrate
from non-carbohydrate sources, namely, amino acids and
glycerol. Thus, humans can exist with little or no dietary
carbohydrate intake
39. Carbohydrates as Food
- Dietary carbohydrate is digested to glucose (80%), fructose
(15%), and galactose (5%).
- Glucose and galactose are actively transported directly into the
blood by the intestinal cells.
- Fructose is absorbed by a specific system that is distinct from
glucose and galactose absorption.
- Part of the fructose is metabolized by the intestinal cells, and the
rest enters the portal blood. Liver and kidney are the other sites of
fructose utilization
40. Carbohydrates as Energy Source
- Carbohydrates are a key substrate for the brain and central
nervous system and a versatile substrate for muscular work,
through their use by oxidative and anaerobic pathways
carbohydrates support exercise over a wide range of intensities.
- Carbohydrates are the preferential energy source for exercise as
they provide a higher yield of ATP compared with fat, leading to
improved gross exercise efficiency.
- The maintenance of high-carbohydrate availability during
exercise relates to glycogen stores and blood glucose that improve
performance of prolonged, sustained or intermittent high-
intensity exercise.
41. Carbohydrates as Energy Source
- The depletion of carbohydrate stores is associated with fatigue as
witnessed by increased perception of effort, reduced work rates
and impaired skill and concentration
- Nutrition strategies to improve sports performance aim at
ensuring an adequate supply of carbohydrates before and during
exercise as well as during the recovery period to limit the
depletion of carbohydrate stores
42.
43. Carbohydrates Importance
- Carbohydrates are of special importance because they are direct
products of photosynthesis and are therefore the primary energy
storage compounds and the basic organic substances from which
most other organic compounds found in plants are synthesized.
- Carbohydrates also are chief constituents of cell walls; they are
the starting point for the synthesis of fats and proteins; large
amounts are oxidized in respiration; another fraction is
accumulated as reserve foods; and still another portion is
variously lost from plants
