bichemistry

1. Biochem-700 3(3-0)
CONCEPTS OF BIOCHEMISTRY
Dr Saba Chaudhry
(PhD Biochemistry)

2. Macromolecules
 Monomers + functional groups
Four types of macromolecules of
interest to us:
 Carbohydrates
 Proteins
 Lipids
 Nucleic Acids

3. Carbohydrates
 Monomer: simple sugar
 eg. Glucose
 Functional group(s):
 Carbonyl
 Hydroxyl
 Polymer: complex
CHO
 Starch, glycogen

4. Structure of
monosaccharide
Fisher
projection
• The straight
chain
structural
formula
Haworth
projection
• Cyclic
formula or
ring
structure
X-ray
diffraction
analysis
• Boat and
chair form

5. A. MONOSACCHARIDES
•Aldoses
• monosaccharides
containing an aldehyde
group

6. Straight chain
Ring structure
Chair form

7. 7

9. 9

10. A. MONOSACCHARIDES
• Ketoses
• monosaccharides
containing a ketone
group

11. DISACCHARIDES
 These are glycosides formed by the condensation of 2
simple sugars.
 If the glycosidic linkage involves the carbonyl groups
of both sugars ( ) the resulting
disaccharide is
 On the other hand, if the glycosidic linkage involves
the carbonyl group of only one of the 2 sugars (as in
maltose and lactose) the resulting disaccharide is
reducing.

14. Reducing versus none
reducing sugar

15. POLYSACCHARIDES
 These are formed by the condensation of n molecules of
monosaccharides with the removal of n-1 molecules of water.
Since condensation involves the carbonyl groups of the sugars,
leaving only one free carbonyl group at the end of a big molecule,
polysaccharides are non-reducing.
 They are of 2 types:
1. Homopolysaccharides (e.g. Starch, Glycogen, cellulose).
2. Heteropolysaccharides (e.g. glycosaminoglycans, glycoproteins)

16. 16

17. 17

19. Aldehyde
group
H-C=O
Monosaccharides
Enantiomers
Mirror images
of each other
Disaccharides
sucrose = glucose +
fructose
Lactose = galactose +
glucose
Maltose= glucose +
glucose
Oligosaccharides Polysaccharides
Homo-
Starch, glycogen,
cellulose
Hetero-
GAGs
Epimers
Differ in
configuration
around one
specific
carbon atom
Isomers
Same
chemial
formula
Ketoses
Keto
group
C=O
Aldoses
glycolipids have an
important role in the
immune response.

20. Functions of Carbohydrates
➢ Carbohydrates are the most abundant organic molecules in
nature.
❖ Providea significant fraction of the dietarycalories for most
organisms
❖ Act as a storage form of energy in the body,
❖ serve as cell membrane components that mediate some forms of
intercellularcommunication.
❖ Carbohydrates also serve as a structural component of many
organisms, including the cell walls of bacteria, the exoskeleton of
many insects, and the fibrous cellulose of plants.
❖ Ribose and deoxyribose in nucleic acids; Galactose in lactose of
milk, in glycolipids, and in combination withprotein in glycoproteins
and proteoglycans.
❖ Diseases associated with carbohydrate metabolism include
diabetes mellitus, galactosemia, glycogen storage diseases, and
lactose intolerance

21. Proteins
 Monomer: amino
acids
 20 total, 9 to 10
essential
 Functional group(s):
 Carboxyl
 Amino
 Polymer
 Polypeptide
 Protein

22. Protein Structure
 The 20 amino acids are joined together by
peptide bonds.
 The linear sequence contains the
information necessary to generate a
protein molecule with a unique three-
dimensional shape.
 The complexity of protein structure is best
analyzed by considering the molecule in
terms of four organizational levels, namely,
primary, secondary, tertiary, and
quaternary

23. Primary structure
 The sequence of amino acids in a protein
 The AA sequence must be written from
the N-terminus to the C-terminus.
 Many genetic diseases result in proteins
with abnormal amino acid sequences,
(Sickle cell anemia, Glu replaced with
Val)

24. Peptide bond
 Peptide bonds are
responsible for
maintaining the
primary structure
 Linkage of many
amino acids
through peptide
bonds results in an
unbranched chain
called a
polypeptide

25. SECONDARY STRUCTURE OF
PROTEINS
 Regular arrangements of amino acids that are
located near to each other in the linear sequence.
 The R group has an impact on the likelihood of
secondary structure formation
 The α-helix, β-sheet, and β-bend (β-turn) are
examples of secondary structures

26. Tertiary Structure
 The configuration of all the atoms in the protein
chain:
 side chains
 prosthetic groups
 helical and pleated sheet regions

27. Tertiary Structure
 Protein folding attractions:
 1. Non covalent forces
 a. Inter and intrachain H bonding
 b. Hydrophobic interactions
 c. Electrostatic attractions (+ to - ionic attraction)
 d. Complex formation with metal ions
 e. Ion-dipole
 2. Covalent disulfide bridges
A protein domain is a conserved part of a given protein sequence
and(tertiary) structure that can evolve, function, and exist
independently of the rest of the protein chain

28. Tertiary interactions

29.  Quaternary structure is the result of non covalent interactions
between two or more protein chains.
 Oligomers are multisubunit proteins with all or some identical
subunits.
 The subunits are called protomers.
 two subunits are called dimers
 four subunits are called tetramers
Quaternary structure

30. 3
0
Lipids
Lipids are bio-molecules that are:
• Hydrophobic in nature because of the high amountof
Hydrocarbons in their structure
• Relatively insoluble in waterbut readily soluble in non-
polar solvents such as Chloroform, Benzene and Ether
• Easily separatedfrom other biological materials by
extraction into organic solvents because of their
hydrophobic properties
• Examples of lipids:
• Fats, Oils, Steroids, Waxes, Fat-soluble Vitamins (Vitamins A, D, E
and K),
LIPIDS

31. 31

32.  Monomer: Fatty
acid
 Functional group(s):
 Carboxyl
 Polymers: many –
depending on the
type of lipid
 Phospholipid
LIPIDS

33. 3
3
What are fatty acids?
Aliphatic Carboxylic Acids containing
Long Hydrocarbon chains that may be
Saturatedor Unsaturated,
Fattyacid has both Hydrophobic and
Hydrophilic properties, thus
are Amphipathic in nature,
• Non-polar Hydrophobic Hydrocarbon
Chain (Tail)
• Polar (-COOH) group (Hydrophilic
Head)
Examples of fattyacids: Palmitic Acid,
Oleic Acid, Arachidonic Acid, Linoleic
Acid, Linolenic Acid, etc.

34. Nucleic Acids
Nucleic acids are:
• molecules that store information for cellular growth
and reproduction.
• deoxyribonucleic acid (DNA) and ribonucleic acid
(RNA).
• large molecules consisting of long chains of
monomers called nucleotides.
34

35. Nucleic Acids
The nucleic acids DNA and RNA
consist of monomers called
nucleotides that consist of a
• pentose sugar.
• nitrogen-containing base.
• phosphate.
Nucleotide

36. Nitrogen Bases
The nitrogen bases in
DNA and RNA are
• pyrimidines C, T, and U.
• purines A and G.
36

37. Pentose Sugars
The pentose (five-carbon) sugar
• in RNA is ribose.
• in DNA is deoxyribose with no O atom on carbon 2’.
• has carbon atoms numbered withprimes to distinguish them
from the atoms in nitrogen bases.
37

38. Names of Nucleosides and
Nucleotides
38

39. Primary Structure of Nucleic
Acids
In the primary structure of nucleic acids
• nucleotides are joined by phosphodiester
bonds.
• the 3’-OH group of the sugar in one nucleotide
forms an ester bond to the phosphate group
on the 5’-carbon of the sugar of the next
nucleotide.
39

40. Primary Structure of Nucleic
Acids
40

41. Structure of Nucleic Acids
A nucleic acid
• has a free 5’-phosphate group
at one end and a free 3’-OH
group at the other end.
• is read from the free 5’-end
using the letters of the bases.
• This example reads
—A—C—G—T—.
41

42. Compaction
of DNA in a
eukaryotic
chromosome