BIOMOLECULES
|
June 30, 2015 |
No Comments |
The
various types of compounds which are found to be essential for animal
for animal life:-
Carbohydrates:
e.g. starch and sugar
Lipids:
e.g. ghee and butter
Proteins:
e.g. complex molecules present in meat and pulses
Vitamins:
e.g. present in food in traces
Hormones:
present in food or synthesised by the body
The
molecules of the above listed compounds form the basis of the life.
Such molecules of organic compounds which build up life system and
required for the growth and the maintenance are called BIOMLECULES.
CELLULAR
ENERGETICS: FREE ENERGY CHANGES IN BIOLOGICAL REACTIONS-
Cellular
reactions follow the basic principles of thermodynamics. Only those
reactions should be spontaneous for which ΔG negative. All the
carbolic reactions proceed with decrease of energy(ΔG<0)but some
important cellular reactions proceed even ΔG is positive.e.g.
Photosynthesis in plants for which ΔG>0. Many anabolism reactions
proceed with increase of free energy i.e. ΔG>0.
A
very common reaction which provides energy in many cellular reactions
is the hydrolysis of adenosine tri phosphate (ATP). The biochemical
unit of energy is ATP. The cell obtains energy for the synthesis of
ATP through photosynthesis / catabolism of nutrients such as
carbohydrates and lipids, this all occurs through coupled reaction.
WHY
ATP MOLECULE IS ENERGY RICH MOLECULE?
The
ATP molecule is consists of four negatively charged oxygen atoms
which are close to each other; the repulsive forces between them are
very high.
These forces makes them high energy molecules, actually
this energy is stored in oxygen-phosphorous bonds.
The oxygen bonds
between the two phosphoric acid residues are high energy phosphate
bonds.
During hydrolysis these bond break, this reduces the number of
oxygen atoms in the molecules and the repulsive forces between
o-atoms decreases, and as a result large amount of energy is
released.
The energy released during this process depends upon the
products formed and the Ph of the solution. AMP and ADP molecules get
converted to ATP molecules during this process.
CARBOHYDRATES:
The
polyhydroxy aldehydes, polyhydroxy ketones, or large polymeric
molecules which on hydrolysis produce polyhydroxy aldehydes,
polyhydroxy ketones, are called CARBOHYDRATES.
STARCH
AND THE SUGARS ARE THE MOST COMMON CARBOHYDRATES.
The
sugar is stored in the body as glycogen (C6H1005)
CALSSIFICATION
OF CARBOHYDRATES:
Carbohydrates
can be classified on the basis of I) Behaviour on hydrolysis ii)
taste
ON
BEHAVIOUR they
are classified into Monosaccharide, Oligosaccharides, and
Polysaccharides.
MONOSACCHRIDES:
These are simple
carbohydrate molecules which can not be hydrolysed into many simpler
molecules. Each molecule represents a complete carbohydrate molecule
unit. They contain 3 to 7 carbon atoms therefore their general
formula (CH20)
n.
Examples:
- glucose, fructose, galactose, and ribose.
OLIGOSACCHRIDES:-
The carbohydrates
whose molecules on hydrolysis give 2 to 9 molecules of
monosaccharides either same or different are called oligosaccharides.
They are divided into di,
tri, tetra and polysaccharides
further.
Examples:
Disaccharides
( C12H22011)
such as Sucrose,
maltose, Lactose,
they produce two molecules of monosaccharides on hydrolysis.
Trisaccharides:
- Carbohydrates
which upon hydrolysis produce three molecules of monosaccharides. The
gen. formula is (C18H32016).
Example:- Raffinose
which on hydrolysis give one molecule of each glucose,
fructose and galactose.
Tetrasaccharides:
- They give four
molecules of mono saccharides on hydrolysis having gen. formula
(C24H42021).
Example:
- Stachyrose
which upon hydrolysis give each of glucose,
fructose and two molecules of galactose.
Polysaccharides
:- Carbohydrates
which upon hydrolysis produce large number of monosaccharides having
gen. formula (C6H1005)
n. where
n = 100 – 3000. such as Starch, Cellulose, and glycogens.
CALSSIFICATION
OF CARBOHYDRATES ON THE BASIS OF TASTE:-
They are classified as Sugars
and non-Sugars
Sugars:
- which are sweet in taste and dissolve in water are called sugars.
All mono and disaccharides are sweet in taste.
Examples:
- Glucose, fructose,
Sucrose, Lactose are
sugars.
Non-Sugars:-
Tasteless polysaccharides which are insoluble in water. They are
generally amorphous in nature.
Examples:
- Cellulose and
Starch.
ADDITIONAL
INFORMATION --- MONOSACCHARIDES
In
addition to hydroxyl group they either contain aldehydic or ketonic
group. The aldehydic being monovalent is either present at the end of
the carbon chain. Hence such monosaccharides are called ALDOSE.
On the other hand ketonic group being divalent can be present
anywhere on the carbon chain. In natural monosaccharides this group
is present normally at the second carbon atom. Hence they are also
termed as KETOSE.
Depending upon the no. of c-atoms these molecules are termed as
trios, tetrose,
pentose, and hexose.
Ketose and aldose are added to the prefixes to the no. of c- atoms.
CHARACTERISTICS:
- They are sweet and water soluble and when heated they get charred.
Due to the presence of 0H-group they can be easily acetylated. They
can be reduced to sugar alcohols. They can be oxidized at the
aldehydic carbon to aldonic acid. Two molecules of monosaccharides
combine with an elimination of water (H20)
molecule to give a disaccharide.
They
undergo oxidation,
reduction, acetylation, react with hydroxylamine, phenyl hydrazine
and fermentation.
ADDITIONAL
INFORMATION ------ DISACCHARIDES.
Its
main source is sugarcane and beet. These include Sucrose, Maltose,
and Lactose. Sucrose is hydrolysed by both enzymes maltase and
invertase.Sucrose is both a α-glucoside and β-fructoside. Hence it
can be concluded that Sucrose consists of α-glucose and β-fructose.
They are held together by α, β-glycosidic linkage.
INVERT
SUGAR: -
Cane sugar is dextrorotatory. On hydrolysis it gives dextrorotatory
glucose and laevorotatory fructose. Therefore a equimolar mixture of
glucose and fructose with opposite signs are called inversion of
sugar or invert Sugar.
POLYSACCHARIDES:
- There can be linear or branched chain polysaccharides.
Polysaccharides are amorphous, tasteless and mostly insoluble in
water. These include starch, dextrin, cellulose, and glycogens. Their
main functions are storage of food.
They
can further be classified as Homopolysaccharides
and Hetropolysaccharides.
Homopolysaccharides
contain same type of monosaccharides. Example: - glycogen, starch,
and cellulose are polymers of glucose.
Hetropolysaccharides:
- they contain two or
more different mono saccharides. Example: - Gums.
STARCH:
- It is odourless, tasteless, and insoluble in water. It is amorphous
and white substance. When boiled it’s granules swells and burst to
form a colloidal solution called starch paste. It is a polymer of
α-glucose and composed of two components amylase(20%)
and amylopectin(80%).
Amylose is water soluble whereas amylopectin is water insoluble. The
structure of glucose is similar as that of amylopectin.
Amylose is
linear polymer whereas amylopectin is a branched one.
AMINO
– ACIDS: - The
carboxylic acids containing amino (-NH2)
group attached to any carbon atoms other than carboxylic carbon are
called amino acids.
An amino acid always contains one H-atom, one R group, one C00H group
and one NH2
group and they are attached to single carbon atom. In aqueous
solution the C00H group looses a proton to form carboxalate ion and
the NH2
group gains this proton to form +NH3
ion. Hence in aqueous solution amino and carboxyl groups are in the
ionized form and amino acid molecule exists as a dipolar
ion. This dipolar ion
is called Zwitter-ion.
Amino acids in dipolar form are amphoteric in nature.
Therefore
in acidic solution, an amino acid exists as a positive ion, and
therefore it migrates to the negative electrode (cathode) when placed
in an electrical field.
In
a basic solution, an amino acid it exists negative ion and therefore
it migrates towards the positive electrode when placed in electrical
field.
The
pH at which the amino acid molecule does not migrate to either of the
electrodes is called the
ISO-ELECTRIC POINT.
D-
L- CONFIGURATIONS OF AMINO ACIDS:
- The α- carbon atom in all the amino acids (except glycine) is
asymmetric (chiral). Therefore amino acids can exist in two stereo
isomeric forms, i.e. D and L forms. These two forms are the mirror
images of each other but are non-superimposable on each other. Thy
are drawn with the reference of glyceraldehydes, in which the
NH2-group
lies on the left hand side of the c- atom in L- configuration and the
NH2-
group lies on the right side of the c- atom in D- configuration. All
natural occurring amino acids are L-isomers. Proteins consist of only
L-amino acids.
The
essential amino acids
which must be present in our food are: - Isoleucine,
Leucine, Lysine, Methionine, Phenylalanine
Threonine, Tryptophan,
Valine, Arginine and Histidine.
PEPTIDES:
- The compounds
formed by the condensation of two or more, or same or different amino
acids are called peptides.
During the
formation of peptide, the amino (NH2)
- group of one of the α-amino acid and the carboxylic (C00H) –
group of another molecule of the same or the different α-amino acid
get condensed with the elimination of the water molecule. During this
process a bond of the type – C0NH- is formed between the two amino
acids. This amide linkage is called peptide
– linkage.
The
peptide formed due to the condensation of only two, three or four
molecules of the same or different amino acids is called dipeptide;
tripeptide and tetrapeptide
bonds respectively.
All
the peptides contain a free amino (NH2)
- group at one end and a free carboxylic (C00H) - group at the other
end. These are called end-groups
or the terminal groups.
Some
important biological peptides are Oxytocin-nanopeptide,
Vasopressin- nanopeptide, Angiotensin-octapeptide.
PROTIENS:
- Proteins are complex nitrogenous organic compounds and are
essential for the growth and development of the body. Proteins are
macro molecules in which large numbers of amino acids are linked with
peptide-bonds. On hydrolysis they give amino-acids, in other words
they are polypeptides of very high molecular mass, (104
– 106g/mol).
Egg,
meat, fish, pulses, and milk are the good source of proteins.
Normally there are 20 amino-acids are present in proteins, and
another six are found in the special tissues. The amino- acids differ
in the side chain groups (R). the properties of amino-acids depend
upon the nature of side chain. The human can synthesise 10 out of 20
amino-acids found in proteins. The other 10 must be supplied in the
diet. Therefore they are called essential
amino-acids. Lack
of proteins can cause a disease called Kwashiorkar.
The elements present in most of the proteins are carbon,
hydrogen, oxygen, nitrogen and sulphur, iron,
magnesium,
phosphorous, etc.
CLASSIFICATION
OF PROTIENS: -
They are classified on the basis of chemical composition. Therefore
there are mainly three classes of proteins.
A)
Simple proteins
B ) Conjugated proteins
C) Derived proteins.
Simple
proteins------
these are made up of only α-amino-acids and they upon hydrolysis
give α-amino-acids.
Example
---------- Albumin,(in white of egg) Glutinin, (in wheat) Keratin,
(in hairs & nails) are simple proteins.
Conjugated
proteins: -------
the proteins which contain organic and inorganic compounds along with
amino-acids are called Conjugated proteins. The non-amino-acid group
of the protein is called prothestic group. This group controls the
biological functions of the proteins. Conjugated proteins are further
classified into -----------------------------------------------------
Lipoproteins
------these contain lipids and amino-acids. The prothestic group in
them is lipids.
Nucleoproteins
----- these contain nucleic acids and amino-acids. The prothestic
groups in them are nucleic acids.
Glycoprotein
------- these contain carbohydrates and an amino-acids.The prothestic
group in them is carbohydrates/sugar.
Chromoproteins
------ they contain
amino-acids and colored pigments.Haemoglobin,
Myoglobin, Haemocynin, Cytochrome, and Riboflavin.
Phosphoproteins-------
they contain amino-acids and phosphate group.
Derived-Proteins:
- The degradation
products obtained from the partial hydrolysis of simple and
conjugated proteins are called Derived
proteins.
CLASSIFICATION
ON THE BASIS OF MOLECULAR STRUCTURE.
On
the basis of structure they are classified as Fibrous
Proteins and Globular Proteins:-
Fibrous
Proteins:- They
are consists of linear, thread-like polypeptide chain which are
arranged and twisted to form long strands (fibres) and they are held
together by hydrogen bonds therefore the inter molecular forces of
attractions are very strong. They are insoluble in water and quite
stable.
Example:
- collagen of tendons,
Keratin in skin, hairs and nails, Fibroin in silk, Myosin in muscles
are Fibrous Proteins.
Globular
Proteins:- The
proteins in which polypeptides are tightly folded into a compact form
are called Globular
Proteins. In these
proteins the hydrocarbon (lipohillic) ends are pushed inwards while
the polar hydrophilic part is oriented outwards therefore these
proteins are water soluble and very sensitive towards temperature and
pH.
Examples:
- All the enzymes,
many hormones such as insulin, thryoglobins, antibodies, Haemoglobin,
fibrinogen, albumin, and venoms of snakes, scorpion, wasp, and bees
are globular proteins.
CLASSIFICATION
ON THE BASIS OF FUNCTION: -
On
the basis of their function these are classified into the following
types: -
1
Structural Proteins
2
Contractile Proteins
3
Hormones
4
Enzymes
5
Blood proteins
ROLE
OF PROTEINS:-
Enzymes:
- All the enzymes
found in the cells are proteins which catalyse large number of
biological reactions in the body.
Hormones:
- Many hormones are proteins in our body. Hormones are chemical
regulators therefore regulate blood pressure. Glycoprotein and
thryoglobins help in the synthesis of hormone thyroxin whereas
nucleoproteins carry the genetic information from the parents to
off-springs.
Haemoglobin:
- It contains the protein called globin and is present in the blood,
transfer the oxygen from lungs to tissues.
Blood
proteins: - thrombin
and fibrinogen are involved in blood clotting
DENATURATION
OF PROTEINS:-
Energetically
the most stable state of a protein is called as its native state or
native form. The native state of a protein is dictated by the amino
acid sequence in the protein. Proteins are very sensitive to heat,
acids, alkalies and even to the electrolytes. Properties of globular
proteins change altogether on heating or on treatment with
acids/alkalies or electrolytes. On heating, water-soluble globular
proteins precipitate out due to formation of water-insoluble fibrous
proteins.The coagulated protein is called as denatured protein.
The
process which leads to change in physical and biological properties
of proteins without affecting its chemical composition is called as
denaturation of proteins.
Denaturation causes changes only in
secondary, and tertiary structures of proteins. The primary structure
of any protein does not change due to denaturation.
Denaturation may
be reversible in some cases.
Denaturation is caused by following
factors
Change
in the pH
Increase
in temperature
Presence
of acids, alkalies, or salts
Exposure
to ultraviolet rays or x- rays
The
most common examples are
Boiling
of egg
Preparation
of cheese from milk.
CHARACTERISTICS
OF ENZYMES:-
EFFECT
OF TEMPERATURE
The
activity of enzymes is highest at near point temperatures. Above this
temperature the enzymes get denatured and lose their activity. At
lower temperature, the rates of enzyme catalyst reactions are slow
because of kinetic effects. In general, the rate of all chemical
reactions increase on increasing the temperature. But the rate of
enzyme-catalyst reaction first increases shows a maximum at about 35-
37oC
and then decreases at high temperature.
EFFECT
OF pH
The rate of pH
on enzyme reaction is complex. The rate of an enzyme-catalyst
reaction usually passes through the maximum at an optimum pH. At
higher or lower pH than this optimum pH, the enzymes tend to get
denatured and therefore lose their activity.
PRESENCE
OF ELECTROLYTES AND ULTRAVIOLET RAYS-
Enzymes lose their activity in the presence of electrolytes or when
exposed to ultraviolet radiations. This is because enzymes get
denatures in the presence of electrolytes or when exposed to
ultraviolet rays.
ENZYME
INHIBITORS Enzymes
are very sensitive to catalytic poisons. Some typical poisons are
HCN, H2S,
CS2.
Enzymes lose their activity in the presence of these substances
because these molecules tend to get absorb on the surface of enzyme
strongly.
EFFECT
OF METAL IONS AND SIMPLE ORGANIC MOLECULES-
most enzymes are associated with some non-protein compounds required
for their activity. These non-protein compounds are called as
prosthetic groups. Prosthetic groups may be metal ions or smaller
organic molecules called coenzymes. Some of the metal ions involved
are those of Zn, Mg, Mn, Fe, Cu, K and Na.Many of the coenzymes are
derived from vitamins, such as thiamine, niacin, riboflavin, etc.
NUCLEIC
ACID-
Nucleic
acids are another important macromolecules present in the cells of
all living organisms.Nucleic acids are long thread like
macromolecules of high molecular masses. Nucleic acids are
responsible for transmission of hereditary characters and for the
bio-synthesis of proteins. Therefore they govern the metabolic
activities in living organisms. They are present in the form of
nucleoproteins.
CONSTITUENTS
OF NUCLEIC ACIDS
Nucleic
acid contains following three contents
A
pentose sugar ( ribose or deoxyribose)
A
nitrogen containing heterocyclic base; a purine or pyridimine base
A
phosphate group
Nucleosides
– The base sugar unit in any nucleic acid chain is called as
nucleoside.The nucleosides are named after the names of the base,
attached at the carbon atom number 1 of the sugar unit.
Eg.
Ribose ribonucleoside, deoxyribose deoxyribonucleosides
Nucleotides
– The base- sugar- phosphate is called as a nucleotide. Nucleotides
are the phosphate esters of nucleosides.
For
eg. Ribose- ribonucleotide, deoxyribose- deoxyribonucleotides
TYPES
OF NUCLEIC ACIDS-
Deoxyribonucleic
acid (DNA)- DNA is
the genetic material and is responsible for heredity character of the
cell. DNA is present in the nucleus of the cell. DNA is the most
stable molecule of the biological world. DNA molecule may be consider immortal.
COMPOSITION
OF DNA-
DNA
contains the following four nitrogen bases-
PURINES- adenine and
guanine,
PYRIDAMINES- thymine and cytosine
Each
unit of DNA strand has only four bases.
- the number of purine nucleotides is equal to the number of pyridimine nucleotides.
- the ratio of adenine(A) to thymine (T) . and guanine (G) to cytosine(C) is one
BIOLOGICAL
SIGNIFICANCE OF DNA-
- DNA acts as a carrier of genetic information from parents to their offsprings
- DNA guides the process of protein synthesis in cells
- DNA is involved in the synthesis of RNA.
RIBONUCLEIC
ACID (RNA)
The
RNA is found to be genetic material in some plants and animal
viruses.RNA is found in nucleolus, cytoplasm and on the membrane in
ribosomes. Each ribonucleotide contains
A
pentose sugar-ribose
Purines-
adenine and guanine
Pyridimines-
cytosine and Uracyl
And
phosphate groups.
Structure
of RNA
Nucleotide
of RNA consist of pentose sugar ribose.
These ribonucleotides are
linked to each other by 3’-5’ phosphodiester bonds.
In this
respect RNA resembles DNA. The polymeric chain of ribonucleotides
forms RNA polynucleotide strands.
RNA
is single stranded except in certain viruses.RNA doesn’t form
helix. The primary structure of RNA differs from DNA in the following
ways:
In
RNA, the sugar residue is ribose, whine in DNA it is 2’deoxyribose
RNA
consists of pyridimine base Uracyl(U) in the place of Thymine (T) in
DNA.
Classification
of RNA
The
organisms which have RNA only as nucleic acid use this RNA in genetic
mechanism. Such type of RNA is called as genetic RNA.
The
organisms which have RNA along with some DNA , use their RNA in
carrying out the orders of DNA.Such type of RNA is called as non
genetic RNA.
The
non genetic RNA is heterogeneous and is classified by cellular
location
MESSENGER
RNA- Messenger RNA
(m-RNA) is short-lived molecule that carries genetic information from
DNA to ribosomes where protein synthesis occurs.
RIBOSOMAL
RNA- Ribosomal
RNA(R-RNA) is an integral part of ribosome that also takes part in
protein synthesis.
About
75% of cellular component of RNA is ribosomal RNA ts molecular mass
varies from 40,000 to 1.5 million.
TRANSFER
RNA- Transfer RNA
(T-RNA) acts as a carrier of amino acids. Its molecules contains
75-78 nucleotide and their molecular mass varies from 23000 to
25000.
Near the middle of its molecule there is a sequence of three
bases called anticodon.
These three bases are hydrogen bonded to a
complimentary sequence in m-RNA during protein synthesis.All t-RNA
molecules have a L- shaped tertiary structure.
The hydrophobic
interactions are a major stabilising force in the tertiary structure
of t-RNA.
FUNCTION
OF NUCLEIC ACIDS: -
They have two important functions to perform----
Replication
The genetic information for the cell is contained in the sequence of
the bases A, T, G, and C in the DNA molecule.
When
the cell divides, DNA molecule replicates and makes exact copies of
themselves so that daughter cell will have DNA identical to that of
the parent cell, in this process the two strands of DNA helix-
unwinds and each strands serves as a template for the synthesis for a
new stand.
Synthesis
of proteins. This
process involves Transcription
and Translation
Translation
:- In this step the
double helix of DNA opens up and two strands of DNA acts as template
for the synthesis of complementary DNA molecule called messenger RNA
(m-RNA)
The
following sequences of bases in m-RNA formed and that of uncoiled
strand of DNA takes place
Uncoiled
strand of DNA : C G A C T T A C C G T A A
Tanscripted
m-RNA : G C U G A A U G G C A U U
Translation:-
During translation, m-RNA directs the protein synthesis in the
cytoplasm of cell with the involvement of another type of RNA
molecule namely , transfer-RNA (t-RNA) and the ribosomal particle.
LIPIDS:-
Lipids are waxy or oily substances which are present in all living
organisms.
Lipids are the constituents of all cell membranes. Lipids
are esters of long chain fatty acids and alcohols. Lipids show some
common characteristics
Lipids
are soluble in the organic solvents but insoluble in water
All
lipids on hydrolysis give mono carboxylic acids ( saturated or
unsaturated)
Lipids
may be broadly classified as
SIMPLE
LIPIDS( triglicerides)- Fats and oils Waxes
COMPLEX
(compound) lipids-Phospholipids Glycolipids
Functions
of lipids
To
form a part of structure of biological membranes. Phospholipids serve
as structural component of cell membrane
To
store energy for the cell. Simple lipids serve as energy reservoirs
for animals
Simple
lipids act as shock absorbers and heat insulators for the bodies of
many organisms including humans.
HARMONES-
chemical compounds secreted by ductless glands which meditate
communication between the cells and control various cellular
activities are called as hormones.
Hormones
may be called as chemical messengers or chemical regulators.Hormones
are produced in ductless glands and transported by blood circulation
to the target tissues for producing inhibitory or stimulatory effect.
Classification
of hormones-Based
on chemical structures hormones fall in three categories-
Steroid
hormones, Polypeptide hormones, Amine hormones
VITAMINES-
A group of bio molecules which are not produced by the body but
required in very small quantities for normal metabolic activities and
healthy growth of human beings and animals are called as Vitamins.
On
the basis of their solubility they can be classified into-
WATER
SOLUBLE VITAMINES- Vitamines which dissolve in water are called as
water soluble vitamins. Eg. Vitamin B and C
OIL
OR FAT SOLUBLE VITAMINS- Vitamins which dissolve in oil or fat are
called as fat or oil soluble vitamins.
Eg.
A, D, E and K.
IMPORTANT
NCERT QUESTIONS
Q1 What
are reducing and non-reducing sugars? What is a structural feature
characterizing reducing sugar?
Q2 Draw
simple fischer projections of D and L glucose. Are these enantiomers?
Q3 Write
down the structures and the names of the products obtained when D
glucose is treated with (a) acetic anhydride (b) hydrocynic acid, (c)
bromine (d) concentrated HNO3,
(e) HI.
Q4 Explain
mutarotation. Explain its mechanism in D glucose.
Q5 What
are essential and non essential amino acids? Give 2 eg. Of each. Give
reasons for the following-
- amino acids have relatively higher melting point as compared to corresponding halo acids.
- On electrolysis in acidic solutions amino acids migrate toward cathode whereas in alkaline solution these migrate towards anode.
Q6 What
type of linkages are responsible for the formation of these
- α- Helix formation
- β- sheet structure
Q7 What
forces are responsible for the stability of α- helix? Why is it
named as 3.613
helix?
Q8 What
is denaturation and renaturation of proteins?
Q9 What
products are obtained on complete hydrolysis of DNA? Write down the
structures of purines and pyridimine bases present in DNA.
Q10
What are complementary bases? Draw structure to show hydrogen bonding
between adenine and thymine bases present in DNA.
Q11 How
does DNA replicate? Give the mechanism of replication. How is the
process responsible for preservation of heredity?
Q12 Answer
the following about protein synthesis-
- How do 64 codons code for only 20 amino acids
- During translation which one of the two-end functional groups of the polypeptide is formed first?
Q13
How are lipids classified? Give an example of each class.
Q14 Hormones
are chemical messengers . Explain.
Q15 Name
the deficiency diseases caused due to lack of Vitamin A , C, E , B1,
B12,
B6,
and K.
REDUCING
ANS NON-REDUCING SUGARS :-
Those
carbohydrates which contain a free aldehydic or a ketonic group and
reduce Tollen’s reagent are called Reducing sugars. E.g. Glucose,
fructose, galactose.
On the other hand which do not reduce Tollen’s reagent and do not
contain free aldehydic or a ketonic group are called non-reducing
sugars. E.g. Maltose,
Lactose, Sucrose.
Chemistry for class 12 ...........
***************************
sharma sir,scceducation,scc,ssc,free cbse notes,free study material,maths,mathematics,science,9718041826,BIOMOLECULES,BIOMOLECULES,BIOMOLECULES
sharma sir,scceducation,scc,ssc,free cbse notes,free study material,maths,mathematics,science,9718041826,BIOMOLECULES,BIOMOLECULES,BIOMOLECULES
0 comments:
Post a Comment