BIOMOLECULES AND THE CELL
90% of living matter
made of C,H,O,N,S,P AND
10% is composed of C,H,O,N,S,P & 10% is composed of K ,
Ca , Na ,Mg , Cl , F, I , Fe , Zn , Mo , Se , Cu , Co.
Among these carbon plays a very
important role because of its tetravalency, isomerism and covalent bond forming capacity.
E.coli
has 6000 types of organic compounds and a
human cell has 1 lakh types of organic molecule.
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MICROMOLECULE
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MACROMOLECULE
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FUNCTIONS
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PROTEINS
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AMINO
ACIDS
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BASIS OF
STRUCTURE AND FUNCTION(STATIC AND DYNAMIC).
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DNA
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DEOXYRIBONUCLEOTIDES
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REPOSITORY
OF GENETIC INFORMATION
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RNA
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RIBONUCLEOTIDES
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PROTEIN
BIOSYNTHESIS
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POLYSACCHARIDES
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MONOSACCHAARIDES
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SHORT
TERM ENERGY
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LIPIDS
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FATTY
ACIDS AND GLYCEROL
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LONG TERM
ENERGY
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Simple inorganic molecules form bio micromolecules. The latter
form biomacromolecules. These inturn
form supra-molecular assemblies, which are
required to form the cell organelles , their
membranes and the cytosol.
All the organelles form a cell. Cells aggregate to form tissues. These then form organs .Organs form organ systems which
coordinate to regulate the organism.
For
a 65 kg man, the body is comprised of the following:
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40 kg
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60%
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Water
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11 kg
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17%
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Proteins
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9 kg
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13.8%
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Lipids
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1 kg
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1.5%
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Carbohydrates
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6.1 kg
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4%
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Minerals.
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Cell
is the structural and
functional unit of
life. The
organelles of a
cell can be
easily isolated by
differential centrifugation.
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Prokaryotic cell
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Eukaryotic cell
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1 to 10 micron.
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10 to 100 micron.
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Well defined nucleus absent
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Well defined nucleus present.
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Nuclear envelope absent
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Nuclear envelope present
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Most cell organelles absent
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All cell
organelles present.
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Primitive
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Advanced
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Cell organelles :-
A. Nucleus:-
§ Largest cell
organelle.
§ Double membrane
envelope.
§ Outer memrane
is connected with
e.r.
§ Nuclear pores
(diameter= 900 nm.)
§ DNA– repository of
genetic information.
§ RNA- protein biosynthesis.
§ Eukaryotic dna :
histone proteins = 1:1.
§ DNA+ histones = nucleosomes.
§ 1
chromosome has millions
of nucleosomes.
§ 46
chromosomes in human
genome.
§ Nucleus has
nucleolus rich in
RNA.
§ Nucleoplasm is
rich in enzymes
like DNA polymerases
and RNApolymerases.
B. Mitochondria:-
§ Mitos- thread , chondrus – granule.
§ Power house
of cell.
§ Various shapes
andv sizes.(dimension = 1 × 3 μm).
§ Double membrane
system.
§ 1- 5 th of cell
volume covered by
2000 mitochondria.
§ Outer membrane – soft and
continuous.
§ Inner membrane
- cristae formation.
§ Matrix of
mitochondria is called
mitosol. It has
chemicals like flavoproteins, cytochromes b, c1, c, a, a3
.(useful in electron
oxidation chain and oxidative
phosphorylation.)
§ Reactions
like biomolecule metabolism,
beta oxidation , citric
acid cycle, ATP production,
heme and urea
synthesis occurs in matrix.
§ The
inner membrane contains
coupling factors.
§ Mitochondria has
its own DNA, RNA,
proteins.
§ It prepares its
own proteins(10% of total
cell protein).
§ Aerobic prokaryotes
evolved into mitochondria
which then lived
with symbiosis with
anaerobic eukaryotes . These
later evolved into
aerobic eukaryotes.
C. Endoplasmic Reticulum:-
§ Smooth endoplasmic reticulum (S.E.R)
- calcium ion supply.
- drug metabolism.
- lipid synthesis. (triacylglycerol, phospolipids, sterols .)
§ Rough endoplasmic reticulum(R.E.R) - granular
in appearance.
{R.E.R – associated with the factories
of protein biosynthesis(ribosomes).}
E.R – disrupts to form
microsomes during cell fractioning.
D. Golgi apparatus
:-
- Dictyosomes(unique cluster of membrane
vescicles) modify to form
golgi complex.
- It
modifies protein by
adding carbohydrates ,
lipids or sulphate moeities to
the polypeptide chain.
- Involved
in membrane synthesis of
organelles like
peroxisomes and lysosomes.
E. Lysosomes :-
- Single
membrane.
- Digestive
tract of cell.
- It’s
enzymes - hydrolases – α- glucosidases, cathepsins , lipases , ribonucleases.
- These
maintain the dynamics
of cellular components.
- Lipofuscin
- wear and
tear pigment or
age pigment accumulate in
cell . Cells rich
in lipofuscin need to
be destroyed by the
post- mortem autolysis.
F. Peroxisomes:-
§ Also
called microbodies.
§ Single membrane.
§ Oval
to round.
§ Contain enzyme
catalase - breakes hydrogen
peroxide into water
and oxygen.
§ Also
oxidises long chain
fatty acids.
§ Synthesizes plasmalogens
and glycolipids.
§ In
plants , called glyoxisomes - do
glyoxylate pathway.
§ Peroxisome biogenesis
disorders have high
amount of c-24
to c-26 and
less plasmalogens.
§ Its
sincere case is
zellweger syndrome -
death within one yr
after birth.(absence of
functional peroxisomes).
G. Cytosol and cytoskeleton:-
§
Cytosol = cell
matrix - it has enzymes,
metabolites, electrolytes in
aqueous.
§
Cytoskeleton
= complex network of
protein filaments
§
It has
microtubules , actin
filaments, intermediate filaments.
