BIO MOLECULES
Carbohydrates : Polyhydroxy aldehydes and ketones are known as carbohydrates.
the carbohydrates may be defined asoptically active polyhydroxy aldehydes or
ketones or the compoundswhich produce such units on hydrolysis.
Monosaccharides: Glucose, Fructose, Ribose, Galactose
Oligo Saccharides: Sucrose, Maltose, Lactose
Poly Saccharides: Starch, Cellulose, Glycogen
Glucose Preparation:
Properties of Glucose:
It suggests presence of carbonyl group.
It indicates presence of carbonyl group and primary alcohol.
It indicates Presence of five hydroxyl groups
It indicates presence of carbonyl group and primary alcohol
Open chain structure of Glucose
Reasons Which Could Not Explain Open Chain Structure –(Ring Structure)
Ring Structure of Glucose:
Ring Structure of Fructose:
Di Saccharides:
Poly Saccharides:
Starch: monomer is alpha D glucose and linkage is C1-C4 & C1-C6 linkages.
It has two components like amylase which is water soluble and linear chain
polymer of alpha D glucose. And other is Amylopectin which is water
insoluble and it is branched chain polymer of alpha D glucose.
Cellulose: Its monomer is Beta D glucose with C1-C4 linkage.
Glycogen is similar structure as starch and it is also known as animal starch.
PROTEINS:
Proteins are vital molecules which are made of amino acids. There are 20
amino acids with which all proteins are made. These amino acids are 10
essential amino acids which are important but not synthesized in human body.
They must taken through diet. Ex. Valine, Leucine
Non essential amino acids synthesized in human body. Ex Glyciene, Alanaine.
Zwitter ion Structure of Amino
Acids
In acid medium Amino Acid has Cationic structure
In Basic medium it has anionic structure. At certain PH it has neutral structure
this is known as Isoelectric point.
Di Peptide:
Two amino acids joined by amide linkage between COOH and NH2 this is also
known as peptide linkage.
Structure of Protein:
Its structure is studied under four categories
1. Primary Structure: It is sequential order of various amino acids present
in protein chain.
2. Secondary Structure: It explains type of hydrogen bond between
carbonyl and amino group. It has two forms.
a) Alpha helix due to intra molecular H bond
b) Beta Pleated sheet structure: Inter molecular H Bond
3. Tertiary Structure: It explains the folding up of protein chain and gives
shape to it. Like Globular protein (water soluble) and Fibrous
protein(water in soluble). And inter particle forces are di sulphide,
vander waals, hydrogen bond electrostatic forces.
4. Quarternary Structure: Some of the proteins are composed of two or
more polypeptide chains referred to as sub-units. The spatial
arrangement of these subunits with respect to each other is known as
quaternary structure.
Denaturation of Proteins: Proteins are sensitive to heat and PH, when it is
subjected these it looses its biological activity. And coverts water soluble
globular protein into water insoluble fibrous protein. During denaturation
primary structure is not affected but higher order structure is affected.
Enzymes: enzymes are known as biological catalysts. These can increase
the rate of biochemical reactions by many times. Ex. Maltase, zymage
liphase.
Vitamines: organic compounds required in the diet in small amounts to
perform specific biological functions for normal maintenance of optimum
growth and health of the organism.
Vitamin A,D,E & K are water insoluble but fat soluble. And B (Except B12 ) & C
are water soluble. They must be taken regularly.
Nuceic Acids:
1. 2 deoxy Ribo Nucleic Acid DNA
2. Ribo Nucleic Acid
RNA
DNA unit is Nucleotide and made up of 2-de oxy ribose, Nitrogen base
(A,G,C,T) and Phosphate group.
RNA unit is has Ribose sugar and N base like A, G,C U and Phosphate
group.
One can understand linkage of nucleic acid by following phosphor di
ester linkage from the diagram
Note: Structures are for understanding linkage but not important.
DNA Structure:
1. Primary Structure: Sequential order of nucleotides
2. Secondary structure: Double helix structure of two strands of Nucleic
Acid chains. Two chains are not idential but complimentary to each
other. Due to Base pair rule i.e A=G, C≡T
Functions of DNA:
1. Replication: DNA molecule is capable of self duplication during cell
division and identical DNA strands are transferred to daughter cells.
2. Protein Synthesis: it is in two steps Transcription and Translation
S.No.
DNA
1
Sugar moiety is 2-Deoxy -D(-)
-ribose
2
Cotains thymine and
cytosine as pyrimidine bases
and guanine and adenine as
purine bases
3
Has double stranded helix
structure
4
Chiefly occurs in nucleus of
cell
5
Very large molecules molecular mass may very
from 6 million to 16 million
6
Has unique property of
replication
7
Controls transmission of
hereditary effects
RNA
Sugar moiety is D(-) ribose
Contains cytosine and uracil
as pyrimidine bases and
guanine and adenine as
purine bases
Has single stranded helix
structure
Mainly occurs in the
cytoplasm of the cell
Smaller than DNA –
molecular mass varies from
20000 to 40000
Does not replicate
Controls synthesis of
protein
VSA of One Mark:
1.Write two main functions of carbohydrates in plants.
2. What is meant by inversion of sugar ?
3. Define the term native state as applied to proteins.
4. What type of bonding helps in stabilising the -helix structure of proteins?
5. What is the effect of denaturation on the structure of proteins?
6. The two strands in DNA are not identical but are complementary. Explain.
SA-1 of Two Marks:
1. Answer the following questions briefly
(i) What are any two good sources of vitamin A
(ii) What are nucleotides?
2. What are essential and non essential aminoacids?Give two example of each
3. Differentiate between (i) Primary strcture and secondary strcture of
proteins
4. What do you understand by the term glycosidic linkage?
5. What is glycogen? How is it different from starch?
6. Why Sucrose is Non Reducing sugar?
7. What are the hydrolysis products of (i) sucrose and (ii) lactose?
SA-2 of Three Marks:
1. Answer the following questions briefly.
(i) What are reducing sugars? (ii) What is meant by denaturation of protein?
(iii) How is oxygen replenished in our atmopsphere?
2.
Define the following terms (i) nucleotides
(b) List out main functions of carbohydrates in organisms.
3. Write the chemical reactions of Glucose with (i) NH2OH (ii)
(CH3CO)2O.Also draw simple Fischer projection of D – Glucose and L Glucose. (b) Name the food sources and deficiency diseases caused due
to lack of any two of the vitamins A,C,E and K.
4. Classify the following into monosaccharides and disaccharides. Ribose, 2-deoxyribose,
maltose, galactose, fructose and lactose.
5. Define the following as related to proteins
(i) Peptide linkage (ii) Primary structure (iii) Denaturation.