This document provides information about the basic biochemistry of cells. It discusses the discovery of cells and cellular structures. It describes that cells are the fundamental unit of living organisms and discusses the cellular pool of organic and inorganic materials. It also summarizes cellular metabolism, the basic chemical constituents of cells including carbohydrates, proteins, lipids, and nucleic acids. It provides classifications and roles of these biomolecules. Finally, it briefly discusses cellular enzymes and factors that affect enzyme activity.

1. Biochemistry of cells
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3. Introduction
Anton Von Leeuwenhoek first saw and described a live cell.
Robert Brown later discovered the nucleus.
The invention of the microscope and its improvement leading
to the electron microscope revealed all the structural
details of the cell.
(i) all living organisms are composed of cells and products of
cells.
(ii) all cells arise from pre-existing cells.
Hence, cell is the fundamental structural and functional unit
of all living organisms.
The collection of various types of molecules in a cell is known
as cellular pool. The cellular pool consists of inorganic and
organic material
The inorganic materials include water , salts and minerals
while the organic compounds are
carbohydrates,proteins,lipids,nucleic acids etc.

4. Metabolism
The term metabolism indicates a variety of reactions
carried out at cellular level
The metabolic reactions can be divided into two main
categories such as :-
a) Anabolic reactions- The reactions in which biosynthesis
of a new cellular material takes place is called Anabolic
reactions
b) Catabolic reactions- The reactions in which a complex
storage product is hydrolyzed and or broken down into
smaller and simpler molecules
Both, Anabolic and Catabolic reactions are catalysed by
biological catalyst called enzymes

5. Basic chemical constituents of
cell
Carbohydrates -
Carbohydrates are the basic components of our food
Carbohydrates are compounds of carbon , hydrogen ,
and oxygen atoms . The proportion of hydrogen and
oxygen is same as in water i.e. 2:1
The general formula is ( CnH2nO2 ) for simple and
(C6H10O5)n, for complex carbohydrates
Simple carbohydrates which are commonly known ars
sugars (glucose, fructose, etc) which participate in
metabolic reaction . Complex carbohydrates like
starch, cellulose,etc.form large storage and
structural units .

6. Classification of carbohydrates

7. 1) Monosaccharides
Monosaccharide carbohydrates are those
carbohydrates that cannot be hydrolysed further
to give simpler units of polyhydoxy aldehyde or
ketone.
They are Crystalline (solid), Soluble in Water and
Sweet to taste.
They consist of 3 to 6 Carbon Atoms
It is classified as Ketose and Aldose

8. 2) Disaccharides
A disaccharide is a sugar (a carbohydrate) composed of
two monosaccharides.
It is formed when two monosaccharides (sugars) are
joined together and a molecule of water is removed.
The co-valent bond that joints monosaccharidesunit is
called Glycosidic bond
They are Crystalline (solid), Soluble in Water and
Sweet to taste.
Ex.- 1)Sucrose = Glucose + Fructose
2) Maltose = Glucose + Glucose

9. 3) Polysaccharides
These are complex carbohydrate formed by
condesation of number of monosaccharides
A single polysaccharides consist of thousands of
monosaccharides .
They are amorphous , tasteless and insoluble in
water.
A Polysaccharide that contain one type of
monosaccharide is called homopolysaccharides .
A Polysaccharide may contain different type of
monosaccharide is called heteropolysaccharides .
For polysaccharides general formula simplifies to
(C6H10O5)n,

10. Role of carbohydrates
The role of carbohydrates is to provide energy for
metabolism.
The Monosaccharides like glucose is main substrate
for synthesis of ATP.
The polysaccharides serves as structural
components of cell membrane and cell wall (
cellulose) and also serves as a reserved food
material (starch) .

11. Proteins
Proteins are long chain of amino acids .
The term protein was coined by Berzelius in 1830.
Proteins serve as an important structural constituent of
cells .
All proteins consists of nitrogen in addition to the
carbon , hydrogen and oxygen.
Two amino acid are condensed by removal of water
molecule is called Residue
A molecule of Protein made of two amino acid Residues
called dipeptide , three residues as tripeptide and
many residues as polypeptide proteins

12. Amino acids which occur in proteins
Glycine
Alanine
Serine
Crysteine
Aspartic acid
Asparagins
Glutamine
Methionine
Threonine
Valine
Leucine
Isoleucine
Lysine
Histidine
Arginine
Phenylalanine
Tyrosine
Tryptophan
Proline

13. Proteins can be classified on the basis
of their nature or composition :-
Simple proteins
These are composed of only one amino acids . e.g. histones ,
zein etc.
Conjugated proteins
These are simple proteins with some non proteins part called
prosthetic group .
e.g. lipoprotein- proteins + lipid
Nucleoprotein- proteins + carbohydrates
Glycoproteins- proteins + carbohydrates
Proteins play important role as -
Enzymes
Hormones like insulin , growth hormone, etc. are proteins.

14. Structural proteins-
this proteins form parts of cells or tissues e.g. keratin in
hair and skin while elastin in connective tissues.
Lipoprotein is present in cell membrane .
Contractile proteins-
these proteins occur in muscles e.g. myosin
Transport proteins-
they are useful for transportation of certain materials e.g.
Haemoglobin in for transport of oxygen , myoglobin for
transport of oxygen in muscles, etc.
Defensive proteins-
They are useful for protection of the body against disease.
e.g. Immunoglobulins , thrombin , for blood clotting.

15. Lipids-
Lipids are a group of oily or greasy consistency.
The term lipid was coined by Bloor (1943) .
Lipids are group of heterogenous compounds like fats
, oils , steroids , waxes etc.
Lipids are insoluble in water but soluble in organic
compounds or non-polar solvents like benzene ,
chloroform , etc.
Lipids are composed of Carbon , Hydrogen , Oxygen
atoms .

16. Classification of lipids
1. Simple lipids –
Fatty acid is a long chain of carbon atoms with a
carboxyl -COOH group at one end .
Glycerol is a three carbon alcohol with three -OH
groups .
Depending on the number of fatty acid molecules
attached to glycerol molecules the esters are
called mono , di , or triglycerides .

17. Fatty acids are classified in two parts
A) Saturated fatty acids :
These fatty acids do not have double bond between
carbon atoms of its chain and consists of maximum
possible hydrogen atoms
e.g. palmitic acid , stearic acid , etc.

18. B) Unsaturated fatty acids
These fatty acids contain double and triple bonds
between carbon atoms of its chain
e.g. oleic acid , linoleic acid , etc.

19. 2. Compound lipids -
These lipids contain some additional elements or
such as nitrogen , phosphorus , sulphur ,
proteins , etc.
e.g. phospholipids , glycerophospholipids ,
glycolipids .

20. 3. Derived lipids -
These lipids are hydrolytic products of lipids. They
include steroids , waxes , carotenoids , essential
oils , etc .
A) Steroids:
Steroids are structurally quite different from
other lipids .
Its molecules of carbon atoms are arranged in
four interlocking rings.
Some biologically important steroids are
cholesterol , bile salt , male and female sex
hormones etc.

21. B) Waxes:
Plant waxes are esters of saturated fatty acids with
long chain alcohols and ketones .
These are secreted by epidermis and form a covering
on stem , fruits , and leaves .
In animals fur and feathers are coated with wax .

22. C) Carotenoids:
Carotenoids are pigments composed of two six carbon
rings with highly unsaturated staright chain of
hydrocarbons.
Carotenoids occur in thylakoids of chloroplast and
chromoplasts of almost all higher plants .
For example alpha and beta carotene , xanthophylls ,
etc .

23. Nucleic acid
Nucleic acids were first discovered by biochemist
Fredrick miescher in 1869 who called them nuclein.
They are of two types Nucleic acids that is-
DNA – Deoxyribonucleic acid , and
RNA – Ribosnucleic acid
Nucleic acids are macromolecules composed of many
small units called nucleotides .
Each Nucleotide is formed by 3 components, i.e.
 Pentose sugar
 Nitrogenous base
 Phosphoric acid

24. Nucleotide = sugar + nitrogenous base
Sugar - pentose sugar can be of two types ribose sugar or
deoxyribose sugar .
Nitrogenous base - their are four types of nitrogenous
bases in which two are purines and two are pyrimidine
Purine bases are double ring compounds distinguished into
adenine and guanine
Pyrimidine bases are single ring distinguished in thymine,
cytosine, and uracil.
Phosphate is present in Nucleic acids as phosphoric acid.

25. DNA
Two strands of
DNA join
together to form
a double helix
Copyright Cmassengale 25
Base
pair
Double helix

26. Structure of DNA
DNA is double stranded helix in which each strand is
made up of thousands of deoxyribose nucleotide.
Two strand of DNA is linked with weak H- bond .
Their are two H- bonds in adenine and thymine while
three H- bonds in guanine and cytosine. Total
number of purine is equal to total number of
pyrimidine
Adenine always pair with thymine and guanine always
pair with cytosine and vise versa .

27. Structure of RNA
RNA is a single stranded . Strand may be straight or
folded upon itself .
RNA is of two types :
Genetic RNA -
RNA is a genetic material in most of the plant viruses
and some animal viruses .
H.Fraenkel showed that RNA is genetic material in
Tobacco Mosaic Virus .

28. Non - Genetic RNA
This type of RNA is present in the organisms in
which the genetic material is DNA .
Non-genetic RNA are of three types :
mRNA :
It is linear molecule having single straight structure .
The synthesis takes place by the process called
transcription .
It carries genetic information from nucleus to the
site of protein synthesis .
It forms about 5% of the total cell RNA

29. rRNA:
It is linear molecule folded at certain regions due to
complementation of nitrogenous bases .
It is associated with ribosomes.
It forms about 80% of the total cell RNA .

30. tRNA:
It is soluble RNA with hair pin or clover leaf like
structure.
This the smallest among three types .
It forms about 10-15% of the total cell RNA .
It carries activated amino acid to ribosomes and
helps in elongation of polypeptide chain during the
process of translation .

31. Enzymes
In living cell the reaction occur at normal body
temperature and pressure due to the presence of
specialised macromolecule, proteintious substance
called Enzymes
The term enzyme was coined by William kuhen in
1878 .
The enzymes which are produced in side the cell are
called endoenzymes and those are produced out are
called exoenzymes.
Most of the enzymes are proteins but all proteins
are not enzymes.

32. Types of enzymes :
The enzymes are classified under six classes as
follows:
Oxidoreductase:
Catalyze oxidation reduction.
They are also termed as dehydrogenase . e.g.
oxidoreductase , NAD Oxido-reductase, etc.
Transferases: help in transfer of chemical group
between a pair of substrate.
e.g. hexokinase , transaminase etc.

33. Hydrolases:
catalyze hydrolysis of ester , ether, peptide, glycosidic,
C-C bonds
e.g. Alakaline phosphatase, etc .
Lyases:
catalyze non-hydrolytic cleavage .
e.g. aldolase, fumarase, etc.
Isomerase:
catalyze interconversion of geometric, optical and
positional isomers.
e.g. triose - phospho - isomerase, phospho-hexose
isomerase etc.
Ligases:
help in joining the two molecules .
e.g. Succinate thiokinase , etc.

34. General Property of Enzyme
• Enzyme accelerate the reaction but do not initiate
it.
• Enzyme themselves do not participate in the
reaction and remains unchanged at the end of the
reaction, Hence they needed in small amount .
• The molecules of an enzyme are larger than that
of substrate molecule and hence that part is
called Active Site of Enzyme.
• Amphoteric Nature: Most of the enzyme are
protein and therefore shows amphoteric nature.
• The enzyme can act with acidic as well as basic
substances

35. • Specificity- Most of the enzyme are specific in
their action, a single enzyme act upon a single
substrate. e.g. enzyme urease can act only upon
uria only and no other molecule.
• Collidal Nature– All enzymes are collidal in nature &
provide large surface area for reaction to take
place .
• Enzyme Optima- Enzyme generally work best under
certain narrowly defind condition reffered as
Optima.
These include appropriate- Temperature and Pressure

36. Factors Affecting Enzyme Activity
Temperature:
The enzymes are affected by change in temperature.
With increase in temperature- increases enzyme
activity, when temperature increase above 60 degree
celsius, the protein undergo denaturation
While when temperature is reduced to freezing point,
the enzyme become inactivated but they are not
destroyed.
PH:
Most of the enzyme are specific to PH and remains
active within particular rate of PH .

37. Substrate Concentration:
The rate of Enzymetic reaction rise with the increase
in substrate concentration upto certain limit .
Inhibitors:
Enzymes are sensitive to the presence of specific
chemical that binds to the Enzyme .
When the binding of enzyme shuts-off the enzyme
activity stops, those chemicals are called Inhibitor
Co-Factor:
To make an enzyme catalytically active, it needs
some non-protein constituent called co-factor .

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