cell and molecular genetics

TOPIC: •Historical background of molecular genetics.•Genetic material in organisms•Structure and properties of nucleic acid.•DNA transcription and its regulation.

WELCOME TO CLASS PRESENTATION OF

Cell and Molecular Genetics

PRESNTED BY:- VIPIN PANDEY

Molecular genetics: it deals with the structure, composition, function and replication of chromosomes and genes, representing genetics material like DNA and RNA.

Historical background of molecular genetics.

YEAR SCIENTIEST CONTRIBUTION1856 G.J. Mendel Transmission of genetic materials

1871 F.Meischer Isolate nucleic acid.

1888 W.Waldeyer Coined the term chromosome.


YEAR

SCIENTIEST CONTRIBUTION

1941

Beadle and Tatum One gene –one enzyme hypothesis.

1952

Hershey and chase DNA is the genetic material.

1953

Watson and Crick Double helix model of DNA.

1954

Gammow Proposed the codon to be triplet.

1955

Benzer Fine structure of gene

1955

Conrat and willims RNA is the genetic material in TMV.

1955

Ochoa and coworkers In vitro synthesis of RNA.

1956

Kornberg and coworkers

In vitro synthesis of DNA.

1958

Mselson and stahl Semi conservation replication of DNA.

1961

Jacob and monod Operon concept of gene regulation.

1970

H.G. Khorana in vitro synthesis of gene.


YEAR

SCIENTIEST CONTRIBUTION

1977

Alwin and kemp Developed the northern blotting technique.

1977

Maxam and Gilbert Chemical method of DNA sequencing.

1983

McClintock Discovered the transposable element

1985

Saiki and Mulis Discovered the Polymerase chain reaction.

1986

Ruska Designing of first electron microscope.

1987

Sanford and coworkers

Developed biolistic gene transfer method.

1990

Barton at al. Formal launch of human genome project.

1990

Wiliiams at al. Developed the RAPD technique.

1991

fodor Developed DNA microarray system.

1995

Vos at al. Developed the AFLP technique.

2001

Venter at al. Human genome project completed.

Any material of plant, animal, microbes or other living containing functional units of heredity is called genetic material.

Properties of genetic material: It is replicated with high fidelity. Its able to express itself. Its also able to store the highly variable information. Its allow errors in low frequency for the origin of new

genetic variation through mutation.

Genetic material in organisms

Nucleic acids were discovered by Meischer in 1871, and called nuclein. The term nucleic acid was first used by altman in 1889.

Nuclein was shown to have acidic properties, hence it became called nucleic acid

Two types of nucleic acid are found Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA)


The distribution of nucleic acids in the eukaryotic cell

DNA is found in the nucleus with small amounts in mitochondria and chloroplasts

RNA is found throughout the cell

NUCLEIC ACID STRUCTURE Nucleic acids are polynucleotides Their building blocks are nucleotides


Genetic material in organismsNUCLEOTIDE STRUCTURE

PHOSPATE SUGARRibose or

Deoxyribose

NUCLEOTIDE

BASEPURINES PYRIMIDINES

Adenine (A)Guanine(G)

Cytocine (C)Thymine (T)Uracil (U)

Ribose is a pentose

C1

C5

C4

C3 C2

O

RIBOSE DEOXYRIBOSE

CH2OH

H

OH

C

C

OH OH

C

O

H HH

C

CH2OH

H

OH

C

C

OH H

C

O

H HH

C

Spot the difference

THE SUGAR-PHOSPHATE BACKBONE

The nucleotides are all orientated in the same direction

The phosphate group joins the 3rd Carbon of one sugar to the 5th Carbon of the next in line.

P

P

P

P

P

P

ADDING IN THE BASES

The bases are attached to the 1st Carbon Their order is important

It determines the genetic information of the molecule

P

P

P

P

P

P

G

C

C

A

T

T

DNA IS MADE OF TWO STRANDS OF POLYNUCLEOTIDE

P

P

P

P

P

P

C

G

G

T

A

A

P

P

P

P

P

P

G

C

C

A

T

T

Hydrogen bonds

DNA IS MADE OF TWO STRANDS OF POLYNUCLEOTIDE

The sister strands of the DNA molecule run in opposite directions (antiparallel)

They are joined by the bases Each base is paired with a specific partner:A is always paired with T G is always paired with CPurine with Pyrimidine This the sister strands are complementary

but not identical The bases are joined by hydrogen bonds,

individually weak but collectively strong

Purines & Pyrimidines

Adenine

CytosineGuanine

Thymine

Watson & Crick Base pairing

The Watson-Crick Structures

Transcription is a process through which a DNA sequence is enzymatically copied by an RNA polymerase to produce a complementary RNA.

The main points related to transcription are listed below :-1.Synthesis of RNA:- mRNA2.Template used:- single strand of DNA.3.Enzyme involved:- RNA polymerase, α, β, β’, and σ

polypeptide4.Genetic information copied:- DNA to mRNA.5.Direction of synthesis. 5’--------->3’ direction.

DNA transcription and its regulation.

The mechanism of transcription consists of three major phases or stages..

1.Initiation2.Elongation3.Termination

Mechanism of transcription.

Initiation

Elongation

Termination

Transcription

Multiple RNA polymerase can be transcribe the same gene at the same time.A cell can synthesize a large number of RNA transcripts in short time.

Self splicing by group ii introns

Transcription regulationTranscription is regulated by activator protein its regulate to RNA polymerase open and close complex.

Transcription regulation

Thank you

cell and molecular genetics

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