Mrs.Sridevi Cell Biology

sandwichtumtumBiotechnology

Dec 16, 2012 (4 years and 10 months ago)

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Cell Biology

Today’s Topics


Size


Shape


Components

Chromosome


Basic techniques


Steps Involve

Genetic
Engineering

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Introduction

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Chromosome
-
Size

Ranges from 0.25
μm

(fungi)


30
μm

(Trillium)

Chromosomes in plants
larger than in animals

Chromosomes in monocots
larger than
dicotyledons

Largest chromosomes:

Lampbrush

chromosomes in
Oocytes

of vertebrates

Polytene

chromosomes
(salivary gland cells of
dipteran

insects)

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Chromosome
-
Shape

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Chromosome
-
Number

Species

Botanical

Name

Diploid

Number of
C
hromosomes

rice

Oryza

sativa

24

maize

Zea mays

20

great millet

Sorghum vulgare

20

peanut, ground nut

Arachis hypogaea

40

soybean

Glycine max

40

mung bean, green
gram

Phaseolus

aureus

22

upland cotton

Gossypium hirsutum

52

mango

Mangifera indica

40

cassava

Manihot utilissima

36

sugarcane

Saccharum

officinarum

80

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Chromosome
-
Components

Satellit
e

Primary Constriction

Secondary
Constriction

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Chromosome
-
Types

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Polytene

Chromosomes

Discovery


C.G.
Balbiani

(1881) in the
salivary glands
of Drosophila.

Characteristic
features


Inter bands,
along the
length of the
chromosome.


Balbiani

ring or
chromosomal
puff.

Other Name


Salivary gland
chromosomes,
as they occur in
the salivary
glands.

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Special Types:
Lampbrush



Chromosomes

Discovery


Observation by
Flemming

(1882)


Description by
Ruckert

(1892)

Occurrence


At the
diplotene

stage of
meiotic
prophase in
oocytes

of
Salamandor


In giant
nucleus of the

unicellular alga
Acetabularia.

Structure


Lateral loops of
DNA extend as
a result of
intense RNA
synthesis.

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Genetic Engineering

Introduction into the bacterial host

Result: Formation of recombinant DNA
or hybrid DNA.

Integration of desired gene into vector,
mostly plasmid DNA of bacterium.

Selection, Isolation and Cutting of
desired gene

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GE
-

Applications

Pharmaceutic
al Industry


Production
of proteins,
enzymes,
hormones,
antibiotics

Agriculture


Formation
of pest
resistant,
disease
resistant
plants,
edible
vaccines

Medicine


Correcting
inborn
genetic
defects.
e.g.,
production
of human
growth
hormone

Forensic
Science


Determine
criminals
through
DNA finger
printing etc.

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