Chapter 13 Applied Genetics

Advances in technology

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