Download Unit-IV GENETIC ENGINEERING

Unit-IV GENETIC ENGINEERING
Introduction to Genetic Engineering
Genetic Engineering
 The study of genes, how genes produce
characteristics, and how the characteristics are
inherited is called as Genetics.
 Genetic engineering, also called genetic
modification, is the direct manipulation of an
organism's genome using biotechnology. New
DNA may be inserted in the host genome by first
isolating and copying the genetic material.
Significance of Genetic Engineering
 An organism that is generated through genetic engineering is
considered to be a genetically modified organism (GMO).
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The first GMOs were bacteria in 1973;
GM mice were generated in 1974.
Insulin-producing bacteria were commercialized in 1982 and
Genetically modified food has been sold since 1994.
Genetic engineering techniques have been applied in numerous
fields including research, agriculture, industrial biotechnology, and
medicine.
 Enzymes used in laundry detergent and medicines such as insulin
and human growth hormone are now manufactured in GM cells,
experimental GM cell lines and GM animals such as mice or
zebrafish are being used for research purposes, and genetically
modified crops have been commercialized.
DNA Fingerprinting
It is a technique that identifies individuals
on the basis of short pieces of DNA.
As no two people have the same
nucleotide sequences, they do not
generate the same lengths of DNA
fragments when their DNA is cut with
enzymes.
DNA Fingerprinting Technique
 DNA profiling (also called DNA testing, DNA
typing, or genetic fingerprinting) is a
technique employed by forensic scientists to
assist in the identification of individuals by their
respective DNA profiles.
 DNA profiles are encrypted sets of numbers
that reflect a person's DNA makeup, which can
also be used as the person's identifier.
 DNA profiling should not be confused with full
genome sequencing. It is used in, for example,
parental testing and criminal investigation.
Although 99.9% of human DNA sequences
are the same in every person, enough of the
DNA is different to distinguish one individual
from another, unless they are monozygotic
twins.
 DNA profiling uses repetitive ("repeat")
sequences that are highly variable, called
variable number tandem repeats (VNTRs),
particularly short tandem repeats (STRs).
VNTR loci are very similar between closely
related humans, but so variable that
unrelated individuals are extremely unlikely
to have the same VNTRs.
DNA fingerprinting in Plant samples
Process of DNA fingerprinting
 It includes the following basic stages:
1. DNA is obtained from a source, which may be as
small as one cell.
2. Polymerase Chain Reaction PCR is used to make
copies of portions of DNA that contains VNTRs.
3. Restriction enzymes are used to cut the VNTRs
DNA into pieces so that VNTRs can be detected.
4. The pieces are separated by Electrophoresis.
5. Comparisons between patterns can be made.
 The DNA profiling
technique was first
reported in 1984 by Sir
Alec Jeffreys at the
University of Leicester in
England, and is now the
basis of several national
DNA databases.
 Dr. Jeffreys's genetic
fingerprinting was made
commercially available in
1987, when a chemical
company, Imperial
Chemical Industries (ICI),
started a blood-testing
centre in England.
DNA Fingerprinting Applications
 In criminal investigations, the DNA fingerprint of a
suspect's blood or other body material is compared to
that of the evidence from the crime scene to see how
closely they match.
 The technique can also be used to establish paternity.
First developed in the mid-1980s, DNA fingerprinting has
been accepted in most courts in the United States.
 DNA fingerprinting is generally regarded as a reliable
forensic tool when properly done, but some scientists
have called for wider sampling of human DNA to insure
that the segments analyzed are indeed highly variable
for all ethnic and racial groups.
 The techniques used in DNA fingerprinting also
have applications in paleontology, archaeology,
various fields of biology, and medical
diagnostics.
 In biological classification, it can help to show
evolutionary change and relationships on the
molecular level, and it has the advantage of
being able to be used even when only very small
samples, such as tiny pieces of preserved tissue
from extinct animals, are available.
Polymerase Chain Reaction-PCR
 Polymerase Chain reaction is a laboratory
procedure for copying selected segments
of DNA from larger DNA molecules.
With PCR, a single cell can provide
enough DNA for analysis and
identification.
Scientists start with a sample of DNA that
contains the desired DNA region.
Targeting specific portions of DNA for
replication enables biochemists to
manipulates DNA more easily .
When more copies of DNA have been
produced it is easy to find, recognize, and
manipulate.
PCR is a test-tube version of the cellular
DNA replication process and require
similar components.
The DNA from the sample specimen
serves as the template for replication.
 A) During one cycle of
PCR, the template DNA is
denatured, so that the two
strands of DNA separate.
This allows the primers to
attach to the template
DNA.
 B) DNA polymerase
create DNA by extending
the primers.
 C) The same process
occurs again, but the
previous round of
replication has made
more template available
for further replication.
 Each subsequent cycle
essentially doubles the
amount of DNA.
Electrophoresis
 It is a technique used to separate molecules,
such as nucleic acids, proteins, or
carbohydrates.
 It separates the nucleic acids on the basis of
size.
 DNA is too long for scientists to work with when
taken directly from the cell.
 To make the DNA more manageable, scientists
cut the DNA into smaller pieces with the help of
restriction enzymes.
 Now, electrophoresis is used to separate
different sized DNA fragments.
 1. Electrophoresis uses
an electric current to
move DNA through a gel
matrix.
 DNA has a negative
charge due to
phosphate that link the
nucleotides.
 DNA migrates towards
the positive pole.
 The speed at which
DNA moves depends on
the length of the DNA
molecule.
 Longer DNA molecules
moves slowly than the
shorter DNA molecules.
Basic Review
1. DNA finger printing Directly examines nucleotide sequence.
Examines segments of DNA, which vary in
lengths between individuals.
Transfer DNA from one person to another.
Uses stem cells.
2. A technique that separates DNA
fragments of different lengths isElectrophoresis.
DNA sequenecing
PCR
DNA fingerprinting.
3. Restriction enzymes-
 cut DNA randomly.
Cut DNA as specific sequences.
Can create sticky ends.
Both b and c are correct.
1. Explain DNA fingerprinting with the help
of a diagram.
2. What are the steps of PCR technique?
3.Enlist the applications of DNA
fingerprinting.
4.Why can DNA in an organism be used to
make the same protein in another
organism?