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
• Isolation 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