GENOME

Presented by:

Francis prathyusha

Introduction

•The complete genetic material of an entire organism

The physical structure of the human genome

• Nuclear genome

• Mitochondrial genome

Nuclear genome

• Comprises approximately 3000 000 000 bp of DNA.

• Divided into 24 linear DNA molecules,

• Shortest 55 Mb in length

• Longest 250 Mb, each contained in a different chromosome.

• 24 chromosomes- 22 autosomes and 2 sex chromosomes

Mitochondrial genome

• A circular DNA molecule of 16,569 bp, many copies of which are located in the energy-generating organelles called mitochondria

The genetic content of the human genome

50-kb segment of chromosome 7

ONE GENE

TWO SEGMENTS

ONE PSEUDOGENE

FIFTY-TWO GENOME WIDE REPEAT SEQUENCES

TWO MICROSATELLITES

OUR 50-KB SEGMENT CONTAINS THE FOLLOWING

GENETIC FEATURES:

• This gene is called TRY4 and it codes for trypsinogen, the inactive precursor of the digestive enzyme trypsin.

One gene

2 genesegments.

• These are V28 and V29-1

• They code for a part of the β T-cell receptor protein

One pseudogene

• Nonfunctional

• Copy of a gene, usually one that has mutated so that its biological information has become unreadable .

• This particular pseudogene is called TRY5

Fifty-two genome wide repeat sequences

• 4 main types of genome-wide repeat

• LINEs (long interspersed nuclear elements),

• SINEs (short interspersed nuclear elements),

• LTR (long terminal repeat) elements and

• DNA transposons,

Two microsatellites

• These are sequences in which ashort motif is repeated in tandem.

• One of the microsatellites seen here has the motif GA repeated sixteen times, giving the sequence 5 –GAGAGAGAGAGAGAGAGAGAGAGAGAGAGAGA–3

3 –CTCTCTCTCTCTCTCTCTCTCTCTCTCTCTCT–5

• The second microsatellite comprises six repeats of TATT.

how similar the human genome is to the genomes

of other organisms??

GENOMES OF ORGANISMS • Eukaryotes

• Prokaryotes

2 types of Prokaryotypes

• (i) the bacteria, (e.g. Escherichia coli), the gram- positives (e.g. Bacillus subtilis), the cyanobacteria (e.g.Anabaena)

• (ii) the archaea, which are less well-studied, and have mostly been found in extreme environments such as hot springs, brine pools and lake bottoms

Plasmids

• Prokaryotes may also have additional genes on independent, smaller, circular or linear DNA molecules called plasmids

1. Linear

2. circular

Varieties of plasmids based onstructure

1. Resistance

2. Bacteriocin-encoded

3. Virulence

4. Phytopathogenic

5. Catabolic

6. Conjugative

7. Sex pheromone

Varieties of plasmids based on function

Genome size

Gene numbers do not correlate with genome size

1. No introns in the genes 2. The infrequency of repetitive

sequences.

Two other features of prokaryotic genomes

• Transposable elements

• Sequences that have the ability tomove around the genome and to transfer from one organism to another, even sometimes between two different species

Mobile DNA"jumping genes".

1. Cause mutations

2. Increase (or decrease) the amount of DNA in the genome.

Types

• Class II Transposons consisting only of DNA that moves directly from place to place.

• Class III Transposons; also known as Miniature Inverted-repeats Transposable Elements or MITEs.

• Retrotransposons (Class I) that – first transcribe the DNA into RNA and then

use reverse transcriptase to make a DNA copy of the RNA to insert in a new location.

What good are transposons?

• They have been called "junk" DNA and "selfish" DNA

JUNK - no benefit SELFISH- more copies

• Many scientists and physicians think that many medical and other benefits could flow from knowing the location and sequence of all the genes

Y??

Human Genome Project

Human genome project

Thank u all