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Chapter 13 Applied Genetics
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What is Applied Genetics?
Applying theoretical concepts of genetics to practical areas.
For example plants, animals, and medicine.
Selective Breeding
Produces organisms with desired traits. For example large heads of grain, juicy
berries, disease resistant plants, calves that produce the most milk.
Inbreeding
Mating between closely related individuals--develops pure blood lines. Insures offspring are homozygous for traits.
Disadvantage: also brings out harmful recessive traits. Ex. Boxers tend to get cancer. The Pharaohs disfiguration.
What is a Breed?
A selected group of organisms within a species that have been bred for particular characteristics.
German shepherds Boxers Klydesdale Horses Himalayan Cats
What is a Hybrid?
Offspring of parents with different forms of a trait.
Ex. Crossing a disease resistant plant with one that produces a lot of yield = a plant that is disease resistant and productive.
Examples wheat, corn, rice, garden vegetables
How do we determine Genotypes? Perform test crosses: cross an
individual of known genotype with one of unknown genotype and observe offspring.
Known genotype is always the recessive.
Example of a Test cross
D D
d
d
Dd Dd
Dd Dd
All offspring areDominant
D d
d
d
Dd
Dd
dd
dd
1/2 offspring are dominant1/2 offspring are recessive
Genetic Engineering
A faster and more reliable method for increasing the frequency of a specific allele in a population.
Involves cutting (or cleaving) DNA from 1 organism into fragments and inserting the fragments into a host organism.
Recombinant DNA
Is made by connecting or recombining fragments of DNA from different organisms.
Transgenic Organisms: contain foreign DNA ( or recombinant DNA)
How to Produce a Transgenic Organism First: isolate the foreign DNA fragment and
cleave the DNA with restriction enzymes. Second:Attach the fragment to a vehicle
called a vector so it can be transported into the host cell.
Third:Transfer the vector to the host and reconnect the vector with the host DNA by gene splicing (rejoining DNA)
How to Produce Transgenic Organisms. Fourth: After the DNA is transferred now
it can replicate every time the host DNA replicates making clones (identical copies) of the recombinant DNA.
Restriction Enzymes
Used to cleave DNA at certain sites. ECORI cleaves at 5’GAATTC3’ BAMHI cleaves at 5’GGATCC3’ HINDIII cleaves at 5’AAGCTT3’
Palendrome: words or sentences that read the same forwards and backwards
Ex. Mom, DAD
Restriction Enzymes
If DNA is cut straight through both strands you have blunt ends Ex.
5’TTAT3’
5’AATA3’ If DNA is cut stagerdly the ends are said to
be “sticky”
5’GATCCGAGGA3’
5’TCCTAGGC3’
Types of Vectors
Vectors transport foreign DNA to a host Biological vectors are viruses, and
plasmids (small rings of DNA found in bacteria cells)
Mechanical Vectors: micropipette or small metal bullets
Why is cloning possible?
Because foreign pieces of DNA introduced into the host cell has been so completely, the foreign DNA is replicated as if it were the host’s DNA.
Advantage to using bacteria in cloning is it replicates quickly.
Cloning Animals: to produce healthy, productive animals that increase yield.
Sequencing DNA
Once pure DNA has been cloned then the sequence of DNA can be determined by:
separating the strands the single strands are mixed with
enzymes, radioactive nucleotides and dyes.
Sequencing DNA
The mixture produces complementary strands of varying lengths.
They are separated according to size by gel electrophoresis, producing a pattern of dyed bans which can be read with a X-ray
The process of Gel Electrophoresis Restriction enzymes either one or
several restriction enzymes is added to a DNA sample. The enzymes cut the DNA into fragments.
The gel: a gel similar to gelatin, is formed so that small wells are left at one end. Into the wells, small amounts of the DNA sample are placed.
The Process of Gel Electrophoresis The electrical Field : the gel is placed in
a solution, and an electrical field is set up so that one end of the gel is positive and the other is negative.
The fragments Move: the negatively charged DNA fragments travel toward the positive end. The smaller fragments, the faster it moves through the gel.
The Process of Gel Electrophoresis Fragments that are the farthest from the
well are the smallest.
Gel Electrophoresis Equipment
Loading of Gels
Xray of a Gel cut with Restriction Enzymes
Recombinant Bacteria in Industry
Bacteria that are able to breakdown pollutants into harmless substances.
Ex. Oil degrading bacteria.
Recombinant Bacteria in Medicine Produce insulin produce human growth hormone
Transgenic Animals
Mouse, worm, Drosphilia Create animals with human disease to
help search for cures.
Recombinant Bacteria in Agriculture Bacteria that helps prevent frost
damage bacteria in soil that converts
atmospheric nitrogen into nitrates faster so the plants can receive it faster.
Transgenic Plants
Herbicide resistant produce internal pesticides increase protein production
The Human Genome
The Human Genome
It is approximately 80,000 genes on 46 chromosomes.
There are 3 billion base pairs of DNA
Linkage Maps
The genetic map that shows the location of genes on chromosomes
Genes that cross over frequently must be farther apart than genes that rarely cross over.
Uses of the Human Genome
Diagnosis of genetic disorders Gene therapy: the insertion of normal
genes into human cells to correct genetic disorders. (Used with CF patients)
DNA fingerprinting
DNA Fingerprinting
Small DNA samples can be obtained from blood, hair, skin, or semen and copied millions of times using a technique called PCR (polymerase chain reaction)
The individuals DNA is cleaved with restriction enzymes and run through gel electrophoresis.
DNA Fingerprinting
The DNA fragments that separate in the gel can be compared with another sample to see if there is a match.
DNA is very distinct like a fingerprint. No two individuals have the same DNA
except Identical twins. In looking a child’s DNA half of the bands
will match the mother and the other half will match the father.
Uses of DNA Fingerprinting
Paternity Testing
Twin’s DNA