Biochemistry, advanced science

1. Adama Science and Technology University
School of Applied Natural Science
Department of Applied Biology postgraduate program
Advanced Biochemistry (Biol5021)
Biochemical and physiological use of
macromolecules
By: Temesgen Assefa
Adama, Ethiopia
January 2, 2018
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2. Outline
Introduction
Carbohydrates
Protiens
Nucliec acids
Lipids
Biochemical and physiological importance
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3. Introduction
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 Biochemistry, sometimes called biological
chemistry, is the study of chemical processes in the
cell.
It deals with the structures, functions and
interactions of biological molecules which provide the
structure of cells and perform many of the functions
associated with life.
Macromolecules are polymers of monomers.
Includes; Carbohydrates, Protiens, Nucliec acids and Lipids

4. Cont…
Polymers of simple sugars
Carbon compounds that contain large
quantities of hydroxyl groups.
Allows to interact with the aqueous
environment and to participate in hydrogen
bonding, both within and between chains.
Represented by the formula (CH2O) n
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A. Carbohydrates

5. . C,H &O ratio = 1:2:1
Carbohydrates are classified into three
subtypes based on the basis of the number of
forming units (sugar).
 Monosaccharides
Disaccharides
 polysaccharides
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Cont…

6. Cont…
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Monosaccharides
simple sugars
May exist as a linear chain or as ring-
shaped molecules.
In aqueous solutions, they are usually
found in the ring form

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Example: glucose, galactose, and fructose =
isomeric monosaccharides, meaning that they
have the same chemical formula (C6H12O6)
but slightly different structures.
Linear structure of monosaccharides
Cont…

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Cont…

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Based on the number of carbon monosaccharides:
Cont…

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Disaccharides formed when two monosaccharides
undergo a dehydration reaction.
During this process, the hydroxyl group (–OH) of
one monosaccharide combines with a hydrogen atom
of another monosaccharide, releasing a molecule of
water (H2O) and forming a covalent bond between
atoms in the two sugar molecules.
include
lactose=Milk sugar; glucose + galactose
Maltose= malt sugar; glucose +glucose
 Sucrose= Table sugar; glucose+ fructose
Cont…

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Cont…

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Cont…
Polysaccharide is a long chain of monosaccharides
linked by covalent bonds.
May be branched or unbranched (linear).
Examples: Starch, glycogen, cellulose, chitin…
Starch= plant reserved food
Glycogen= animal reserved food and more branched
Cellulose = plant cell wall component
Chitin=insects exoskeleton & fungal cell wall
Peptidoglycan= bacterial cell wall

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Cont…
Biochemical and physiological Functions of carbohydrates
 Energy storage and production. E.g. Monosaccharides
supply 3.74 kcal/g, disaccharides 3.95 kcal/g, while starch 4.18 kcal/g;
on average 4 kcal/g.
Exert a protein-saving action
Form other bio molecules
Necessary for the normal lipid metabolism
“Fats burn in the fire of carbohydrates“ L. Pasteur
Oxygen transport
Indispensable for the maintenance of the integrity
of nervous tissue (Some CNS areas use glucose to
produce energy)
Two sugars, ribose and deoxyribose, are part of
the bearing structure of RNA and DNA. 13

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For example, at hepatic level glucuronic acid,
synthesized from glucose, combines with endogenous
substances, as hormones, bilirubin etc., and exogenous
substances, as chemical, bacterial toxins or drugs,
making them atoxic, increasing their solubility and
allowing their elimination.
 Act as a reaction intermediates or accessories.
For example vitamin B12 (Riboflavin) has ribose sugar
and it is involved in vital reactions at cellular level.
Detoxifying processes
Cont…

15. Aid in gut motility
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Cont…
They are also found linked to many
proteins and lipids.
 Structural elements
E.g. cellulose and chitin (homopolysaccharides)
and peptidoglycan (heteropolysaccharide).

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Cont…
Simple diagrammatic representation about (CH2O)n

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B. Proteins
Cont…
Polymers of amino acids
aa’s are covalently attached to one another
to form long linear chains called polypeptides.
Molecular structure
of polypeptides
showing the
sequence of amino
acids

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Cont…
It may be structural, regulatory, contractile, or
protective; they may serve in transport, storage, or
membranes; or they may be toxins or enzymes.
The functions of proteins is very diverse because
there are 20 different chemically distinct amino acids
that form long chains.
Each amino acid has the same fundamental structure.
NH2 (Amino group)
Carboxyl group (–COOH)
hydrogen atom and
R-group.

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Cont…

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The chemical nature of the R group determines the
chemical nature of the amino acid within its protein
(that is, whether it is acidic, basic, polar, or nonpolar).
The sequence and number of amino acids
ultimately determine a protein’s shape, size,
and function.
Each amino acid is attached to another amino
acid by a covalent bond, known as a peptide
bond, which is formed by a dehydration
reaction.
Cont…

21. Four levels of protein structure:
 primary
 secondary
Tertiary
quaternary
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Cont…
Protein Structure
The shape of a protein is critical to its function

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Cont…
The unique sequence and number of amino
acids in a polypeptide chain is its primary
structure.
 Folding patterns resulting from interactions
between the non-R group portions of amino
acids yields secondary protein structure.
The most common are the alpha (α)-helix
and beta (β)-pleated sheet structures.
In the alpha helix, the bonds form between
every fourth amino acid and cause a twist in
the amino acid chain.

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Cont…
In the β-pleated sheet, the “pleats” are formed by
hydrogen bonding between atoms on the backbone of
the polypeptide chain
The α-helix and β-pleated sheet structures are found
in many globular and fibrous proteins.

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Cont…
It is caused by chemical interactions between various
amino acids and regions of the polypeptide.
The unique three-dimensional structure of a
polypeptide is known as its tertiary structure
Some proteins are formed from several
polypeptides, also known as subunits, and the
interaction of these subunits forms the quaternary
structure.

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Cont…
The four levels of protein structure (Source: National Human Genome Research Institute)

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Cont…
Biochemical and physiological Roles of Protein
catalyzing chemical reactions
synthesizing and repairing DNA
transporting materials across the cell
receiving and sending chemical signals
responding to stimuli
providing structural support

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Cont…
Structure
Structural proteins form the basis of your cells,
which come together to form organs, muscle tissue,
bones, skin, hair and nails.
Movement
Muscle fibers consist of the proteins actin and
myosin, organized in a manner that allows them to
slide back and forth to shorten or lengthen a muscle
Communication
Some proteins function as chemical-signaling
molecules called hormones. And also enzymes.
Immunity
WBC’s synthesize several antibodies and chemokines, to help
protect you against infection and inflammation.

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Cont…Transport and Storage
Hemoglobin is a protein that carries oxygen to the
tissues throughout your body
Myoglobin stores small amounts of oxygen in your
muscles
Respiratory system
Hemoglobin (composed of four protein subunits)
transports oxygen for use in cellular metabolism
Energy
protein can provide energy to your cells
Catalysis
Proteins are enzymes and involved in synthesis and
breakdown reaction (Drive Biochemical Reactions)

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Cont…
Role Examples Functions
Digestive enzyme Amylase, lipase, pepsin Break down nutrients in
food into small pieces that
can be readily absorbed
Transport Hemoglobin Carry substances
throughout the body in
blood or lymph
Structure Actin, tubulin, keratin Build different structures,
like the cytoskeleton
Hormone signaling Insulin, glucagon Coordinate the activity of
different body systems
Defense Antibodies Protect the body from
foreign pathogens
Contraction Myosin Carry out muscle
contraction
Storage Legume storage proteins,
egg white (albumin)
Provide food for the early
development of the
embryo or the seedling
Generalized Protein types and functions

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Cont…
C. Nucleic Acids
Key macromolecules in the continuity of life.
Carry the genetic information of a cell.
Two types : DNA and RNA
DNA is the genetic material found in all living
organisms, ranging from single-celled bacteria to
multicellular mammals.
RNA is mostly involved in protein synthesis

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Cont…
The main function of DNA is to store the genetic
information that cells in the body need to function.
RNA plays an important role in converting the
information from DNA into proteins.
DNA and RNA are made up of monomers known as
nucleotides.
Each nucleotide is made up of three components: a
nitrogenous base, a pentose (five-carbon) sugar, and a
phosphate group.

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Cont…Nucleotide components

33. Is a double-helical structure/double stranded
The strands are bonded to each other at their bases
with hydrogen bonds, and the strands coil about each
other along their length
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Cont…DNA

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Cont…
The sugar and phosphate groups forms the backbone of the
DNA and the bases act as a ladder.
The rule is that nucleotide A pairs with nucleotide T, and G
with C as follows

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Cont…
RNA
Ribonucleic acid
Convert genetic information from genes into amino
acid sequences of protein.
In some viruses, RNA contains the genetic
information. E.g Tobacco mosaic virus
RNA is of three types, they are tRNA , mRNA and
rRNA.
 mRNA - Carries genetic information between
DNA and ribosome, and it also directs protein
synthesis.

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Cont…
r-RNA- a major component of the ribosome;
they catalyze the formation of peptide bond.
t-RNA act as a carrier molecule for the amino acids
that are used in protein synthesis. It is also responsible
for decoding the mRNA

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Biochemical and physiological functions of nucleic acids
Cont…
Serve as energy storage
Form a portion of several important
coenzymes such as NAD+, NADP+ and FAD.
Serving as mediators of numerous important cellular
processes such as second messengers in signal
transduction events. E.g. cyclic-AMP
 Controlling enzymatic reactions through allosteric
effects on enzyme activity.

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Serving as neurotransmitter and as signal receptor
ligands. Adenosine can function as an inhibitory
neurotransmitter, while ATP also affects synaptic
neurotransmission throughout the central and
peripheral nervous systems. ADP is an important
activator of platelet functions resulting in control of
blood coagulation.
Serving as activated intermediates in numerous
biosynthetic reactions. E.g. S-adenosylmethionine (S-
Ado Met or SAM= involved in methyl transfer rxn.
It store and transfer genetic information & directs
synthesis of proteins
Cont…

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Cont…
D. Lipids
 Lipids are a class of macromolecules that are
nonpolar and hydrophobic in nature b/c it
include only nonpolar carbon-carbon or carbon-
hydrogen bonds. E.g. fats and oils, waxes,
phospholipids, and steroids.
Fats and oils are a stored form of energy and
can include triglycerides.
Triglyceride, consists of two main
components glycerol and fatty acids.

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Cont…
Fatty acids may be
 saturated= only single bonds b/n C atoms
 unsaturated= chain contains a double bond
 Most unsaturated fats are liquid at room
temperature and are called oils b/c the
double bond causes a bend or a “kink” that
prevents the fatty acids from packing tightly,
keeping them liquid at room temperature.
Based on no of double bonds:
Mono unsaturated- one double bond. E.g.
Olive oil
Poly unsaturated- more than one double bond.
E.g Canola oil

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Cont…

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Cont…

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Cont…
Saturated fats tend to get packed tightly and
are solid at room temperature. E.g Animal fats
Mammals store fats in specialized cells called
adipocytes, where globules of fat occupy most of the
cell.
In plants, fat or oil is stored in seeds and is used as a
source of energy during embryonic development
Unsaturated fats help to improve blood cholesterol
levels, whereas saturated fats contribute to plaque
formation in the arteries, which increases the risk of a
heart attack.

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Cont…
Unlike the phospholipids and fats, steroids
have a ring structure
Phospholipids are modified so that a phosphate
group (PO4
–) is added to one of the fatty acids.
Waxes are made up of a hydrocarbon chain with an
alcohol (-OH) group and a fatty acid.
Steroids are hydrophobic. All steroids have four, linked carbon
rings and several of them, like cholesterol, have a short tail. E.g
Cholesterol synthesized in liver

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Cont…
Biochemical and physiological Function of Lipid
Chemical messengers
Storage and provision of energy
Storage lipids are triacylglycerols = fatty acids and a
glycerol
Lipids are insoluble in aqueous solutions and hence can be
stored readily in the body as a food reserve.
Maintenance of temperature
Layers of subcutaneous fat under the skin also help in
insulation and protection from cold
Membrane lipid layer formation
Membrane lipids are made of polyunsaturated fatty acids

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Cont…
Cholesterol formation
Much of the cholesterol is located in cell
membranes
It maintains the fluidity of membranes by
interacting with their complex lipid components,
specifically the phospholipids such as
phosphatidylcholine and sphingomyelin.
Also it is the precursor of bile acids, vitamin D and
steroidal hormones

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Cont…
Prostaglandin formation and role in inflammation
The essential fatty acids, linoleic and linolenic acids
are precursors of many different types of eicosanoids,
including the hydroxyeicosatetraenes, prostanoids
(prostaglandins, thromboxanes and prostacyclins),
leukotrienes (and lipoxins) and resolvins etc. these play
an important role in pain, fever, inflammation and
blood clotting.

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Cont…
Essential nutrients
Some lipids are essential nutrients like fat-soluble
vitamins A, (necessary for vision) and D (necessary
for calcium metabolism) present in some fats and oils
of animal origin, vitamin E (prevention of
autoxidation of unsaturated lipids), present in
vegetable oils, and vitamin K (normal clotting of
blood) present in green leaves, essential fatty acids,
in particular linoleic and α-linolenic acids, founders
of the family of omega-6 and omega-3 fatty acids
respectively.

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Cont…
Structural component
Lipids are an important constituent of the cell
membrane
Antibiotic agent
Squalamine, a steroid from the blood of sharks, has
been shown to be an antibiotic and antifungal agent
of intense activity and sharks rarely contract
infections and almost never get cancer.
Fatty acid absorption
 Phospholipids play an important role in the
absorption and transportation of fatty acids.

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Cont…Hormone synthesis
The sex hormones, adrenocorticoids, cholic acids
and also vitamin D are all synthesized from
cholesterol, a steroidal lipid.
Vitamin carriers
Lipids act as carriers of natural fat-soluble
vitamins such as vitamin A, D and E.
Blood cholesterol lowering
stearic acid diet lowers blood cholesterol by 14%
of palmitic acid diet and 10% of oleic acid diet.
(Scott Grundy and Andrea Bonanome (1988),
University of Texas )

51. Thank You!!!
Question
January 2, 2018 51