Frontiers of Genetics

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23 Οκτ 2013 (πριν από 3 χρόνια και 11 μήνες)

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Frontiers

of

Genetics

Chapter 13

Applications of Biotechnology


Biotechnology
: The use of organisms to
perform practical tasks for human use.


DNA Technology
: Application of biotechnology
in which genomes of organisms are analyzed and
manipulated at the molecular level


Bacteria, such as E. coli, serve as useful
models for gene manipulations


Do not undergo meiosis (reproduce asexually)


Still have means of genetic recombination


This natural recombination process is capitalized on in
current DNA technology procedures

Selective Breeding


Cross
-
breed organisms with desired traits


Enhance expression of trait


Produce combination of desired traits



Lederberg & Tatum’s Experiment

The Human Genome


An organism’s complete
set of genetic material,
defined by order of
DNA bases is known
as its genome


DNA is thousands of
times longer than the
diameter of the nucleus


DNA is able to fit into
the nucleus because of
an elaborate packing
system

The Human Genome Project


13 year project to sequence the entire human
genome (nucleotide sequence)


Knowing sequence is just the first step, must
then distinguish between non
-
coding (introns)
and coding (exons) regions


Finally functions of all resulting polypeptides
must be determined


Gene identification is useful in evolutionary
research as well as diagnosing , treating and
possibly preventing diseases/disorders.

Recombinant DNA Technology


Combine genes from different sources, even different
species, into a single DNA molecule


Bacteria have small circular pieces of DNA called plasmids
separate from their larger single chromosome


Plasmids can replicate and pass between bacterial cells
allowing gene sharing


associated with antibacterial
resistance


Genetic Engineering


Plasmids are used to add
genes for useful
products into bacteria
through a process called
gene cloning


Remove plasmid


Add useful gene


Reinsert in bacteria where
genes are copied many
times

Genetically Engineering Insulin

Genetically Engineering Insulin

How can we do this?


Restriction enzymes are proteins that cut genes at specific DNA
sequences.


Over 75 different kinds of restriction enzymes are known; each
one “recognizes” and cut DNA at a particular sequence


Restriction enzymes allow DNA to be cut into fragments that can
be isolated, separated, and analyzed.


The cut ends produce matching
“sticky ends”
on the DNA
fragment and the cut plasmids.



Restriction Enzyme Action & Cloning into a Plasmid

Animation


Steps in Cloning a Gene

Inserting a DNA Sample into a Plasmid

Examples of Genetic Engineering

Genetic Manipulation of Plants


Genetic engineering of plants is much easier
than that of animals.


natural
transformation system
(
Agrobacterium
tumefaciens
)


plant
tissue can
re
-
differentiate


transformation
and regeneration are relatively
easy for
many


The soil bacterium
Agrobacterium
tumefaciens

can
infect wounded plant tissue, transferring a
large plasmid, the Ti plasmid,
containing
contains genes for
the synthesis of (1) food for
the bacterium, and (2) plant
hormones.


This plasmid
has been genetically modified
("disarmed")
and used to insert
a gene that can
be used as a selectable
marker as well as a gene
of interest, such as herbicide resistance, virus
tolerance, decreased sensitivity to insects or
pathogens.


DNA
can
now be
delivered into the cells by
small, µm
-
sized tungsten or gold bullets coated
with the DNA. The bullets are fired from a
device that works similar to a
shotgun

called a
gene gun.

ANIMATION

Cloning

Natural v. Artificial Twinning Animation

Cloning Animation

Gel Electrophoresis

RFLP Animation

Layout of an Electrophoresis Gel

Loading the Wells of a Gel

Uses of Electrophoresis


I
solation of DNA fragments

so that they can
be incorporated into a
plasmids

or some other
vector
.



Creating a DNA map
so that we know the
exact order of the nucleic acid base pairs (A, T,
C, or G) along a DNA strand.


Perform

DNA Fingerprinting
, which can be
used to test organic items, such as hair or
blood, and match them with the person that
they came from.


This is useful in criminal
investigations.


DNA Fingerprinting Animation

Polymerase Chain Reaction


Method of photocopying DNA in vitro to provide large supply
to avoid needing large sample size of cells to extract it (DNA)
from.

Animation

Prokaryotic Control of Gene Expression

Animation 1

Animation 2

Eukarotic

Controls of Gene Expression


Gene expression is the
transcription and
translation of genes into
proteins


Eukaryotic controls are
elaborate than
prokaryotes


Genes are not controlled
in clusters


Proteins called
transcription factors
regulate transcription by
binding to promoters or
RNA polymerase


Turned ON or OFF by
chemical signals in the cell

Cellular Differentiation

STEM CELLS
are cells that
are undifferentiated and have
the potential to differentiate
into various types of cells

Homeotic Genes


“Master switches”;
control formation
of body parts in
specific locations


Small changes in
these genes can
result in major
morphological
changes