CELL,CHROMOSOMES,DNA,GENE

1. BIOCHEMISTRY
ASSIGNMENT
SUBMITTED BY:
S. SABANA SHARMI
1ST MSC ZOOLOGY
ROLL NO:22MZOO03
SUBMITTED TO:
Dr. V. TAMIZHAZHAGAN
Assistant professor
PG department of Zoology
Syed Ammal Arts and Science College.

2. Introduction
 Cell
 Chromosomes
 DNA
 Gene

3. Cell
 Cell is the basic structural and functional unit of all living organisms.
 The Cell was first discovered by Robert Hooke in 1665

4.  Each cell contain smaller organelles that perform various function such as
metabolism, transportation and secretion of substance.
For eg:Red Blood cells are the oxygen carriers in the body.
 They provide structure for the body, take in nutrients from food, convert those
nutrients into energy, and carry out specialized functions.
 Humans have more number of cells compared to that of bacteria.

5. Types of cells
 Various types of cells perform different functions.based on cellular structure,there are two
types of cells.
1.Prokaryotic cells
2.Eukaryotic cells

6. Prokaryotic cells
 Prokaryotic cells have no nucleus
 They all are single-celled microorganisms.
Eg:Bacteria,Archaea
 The hereditary material can either be DNA or RNA.
 The Prokaryotic cells are primitive cells.
 They can perform Reproduction, Respiration, Digestion and other Biological
process.

7. Eukaryotic cells
 The cells containing a true nucleus are called Eukaryotic cells.
 Eukaryotic cells are the advanced and complex cells. They originated from
prokaryotic cells.
 They can maintain Different Environment in a single cell that allow them to carry
out various metabolic reaction.
 This help them grow many times larger than the prokaryotic cells.

8.  Chromosomes are self-reproducing thread like structures packaged with DNA located inside the
nucleus.
 Chromosomes means coloured body.
 Chromosome Carry gene and Help inheritance or transfer of characters From the parents to the
offspring .
 They are the vehicles of heredity.
 Each chromosomes is made of protein and single molecule of DNA.
 Chromosomes play an important role during cell division. They protect the DNA from getting tangled
and damaged.
 The chromosomes control the metabolism of an organism.
 In human each cell Normally contains 23 pairs of chromosome,for a total of 46.
Chromosomes

9. Chromosomes are classified into four
types.
The shape of chromosomes is largely determined by the position of its centromere.

10.  Telocentric: The centromere is located at the end of the chromosomes.there is only one
chromosomal arm.Such chromosome are Rare across many species.
* It exists normally in certain species of protozoa.
 Acrocentric:These are rod-like chromosomes having a very smaller arm and a very long arm.
This is characteristics of Locusts.
 Sub-metacentric:These chromosomes are L-shaped having unequal arms.
 Metacentric:These Chromosomes are V-shaped.they have arms equal in length.they are
characteristics of Amphibia.

11. DNA (Deoxyribonucleic acid)
 DNA is the molecular of heredity. It is function as the genes.
 Individual organism has unique DNA like a finger prints.
 DNA is well suited for biological information storage.
Discovered of DNA:
 Many people believe that American biologist James Watson
And English physicist Francis crick Discovered by DNA. In reality,
DNA was first identified by Swiss chemist Friedrich miescher.
 Watson and crick in 1953 designed the structure of DNA.
 They were awarded with Noble Prize in 1962 for this work

12.  DNA is a double stranded molecule consists of 2 polynucleotide chain running in opposite directions.
 DNA is a nucleic acid. It is a macromolecule.it is made up of two chains each chains is a
polynucleotide chain.
 Each polynucleotide is made up of many small unit called nucleotides. Each nucleotide is made Up
three chemical components, namely a Phosphoric acid, Deoxyribose sugar and nitrogen base
 The nitrogen bases are Adenine(A), Guanine(G), Thymine(T) ,Cytosine(C)
 Adenine and Guanine are single-ringed purines.
 Cytosine and Thymine are double-ringed Pyrimidines.

13.  In Eukaryotes,DNA is presented in nucleus surrounded by nuclear membrane.
 In prokaryotes, DNA is presented in nucleoid region of cytoplasm without nuclear membrane.
 In virus,DNA is presented in the core of virus surrounded by protein layer is called as capsid.
Functions of DNA :
*it is extremely large, allowing lotS of Genetic information to be stored.
* DNA control all developmental processes of an organism and all life
Activities.

14. Gene
 A gene is the basic physical and functional unit of heredity.gene are made up of DNA.
 Gene are segment of DNA located on chromosomes
That Contain the instructions for protein production.
 Gene are capable of self-duplication producing their
Own exact copies.
 A single human chromosomes contain 100 to thousands
of genes.

15. Types of Genes
 Pleiotropic genes: The Genes Which produce changes in more than one
character is called pleiotropic gene.
 Modifying gene: The gene which can’t produce a character by itself but interacts
with other to produce modified effect is called modifier gene.
 Inhibitory gene: The gene which suppresses or inhibits the expression of
another gene is called inhibitory gene.

16. Reference
 Wilson, E.B(1925).the cell in development and heredity, Ed. 3.macmillian,new
York. P. 923
 DNA Technology the awesome skills by I. Edward Alcoma
 Molecular biology of the gene by James. D. Watson.
 Jain H.K,gene structure & concept; edition V; page no:192-200
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