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.
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)
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
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
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
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
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
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
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—.
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