Genetic Technology CH 13

Applied Genetics Selective breeding - produces organisms with desired traits. 1. Takes time, patience and several generations. 2. Increases the frequency of desired alleles.

Inbreeding – develops pure lines. 1. Mating closely related individuals. 2. Results in offspring that are homozygous for most traits. 3. Can bring out harmful, recessive traits because there is a greater chance that two closely related individuals both carry a harmful recessive allele for the trait. Click inside box to play movie

Hybrids Hybridization – crossing parents with different forms of a trait. Plants produced from crossing two cultivars often bigger and better. Animals – when two species are crossed sterile hybrids are produced. Zorse – cross between a horse and a zebra.

Determining Genotype A test cross is done to determine the genotype of an unknown dominant individual. 1. A dominant phenotype can be homozygous or heterozygous. 2. Cross the unknown to a homozygous recessive. If any of the offspring are recessive, you know the unknown is heterozygous. Homozygous recessive dd Unknown Unknown is Dd Unknown is DD

Genetic Engineering Faster and more reliable than traditional, selective breeding methods Recombinant DNA – connecting or recombining fragments of DNA from different sources Transgenic Organisms OR Genetically Modified Organisms (GMOs) – plants and animals that contain foreign DNA

Creating GMOs Three-step process Restriction enzymes cut, or cleave, the DNA If same enzyme is used to cleave DNA in two different organisms, the DNA pieces will stick together “Sticky ends” are key to recombinant DNA Vectors transfer DNA to host cell Biological – viruses and plasmids Mechanical – micropipettes and gene guns

FYI - More Info on Gene Gun

3. DNA is rejoined by gene splicing Transferred to host by one of the vectors Duplicates as host cell divides

GMOs in Agriculture Soy and corn are the most widely modified organisms in agriculture. Both are very important to our economy!

GMOs in Agriculture Different GMOs have different types of resistance – depends on what genes have been recombined in the organism Herbicide resistance – Hra gene from tobacco plant Insect resistance – genes from Bacillus thuringiensis (Bt) bacterium Drought resistance

Pros and Cons The Good The Bad GMOs can save farmers money – herbicides and lost crops (death) are costly! Potential solution to world hunger – feed the growing human population The Bad Weeds developing herbicide resistance Insects developing insecticide resistance Arms race against mother nature?!

Testing for GMOs DNA extraction Polymerase Chain Reaction (PCR) Method of replicating DNA outside of living organisms. Essential for analysis of DNA. Has allowed molecular genetics to become part of criminal investigations. Gel Electrophoresis used to separate the DNA pieces cut with restriction enzymes by size

Applications of DNA Technology Cloning of organisms, as well as genes. Pure DNA for study of specific genes from PCR. Recombinant bacteria. a. industrial use – break down pollutants. b. medical use – produce hormones, insulin or. amino acids. c. agriculture Transgenic animals – scientists can create animals with human diseases and animals that can produce human materials.

Transgenic plants – have been engineered to resist herbicides, produce internal pesticides and increase their protein production.

Human Genome The Human Genome Project – has mapped and sequenced all human genes. A. We have a linkage map. 1. 35 - 40,000 genes on 46 chromosomes. 2. We know where the genes are located, but do not know the function of all genes.

Applications of the Human Genome Project Diagnosis of genetic disorders followed by gene therapy. A. Insertion of normal genes into human cells to correct genetic disorders. B. fetal diagnosis and therapy.

A. Criminal investigations. DNA Fingerprinting – no two individuals have the same DNA fingerprint, except identical twins. A. Criminal investigations. B. Identification of family members, dead or alive.

Stem Cells Stem cells are unspecialized cells that continuously reproduce Have potential to differentiate into one or more types of specialized cells Identical stem cells Stem cell SELF-RENEWAL (copying) Stem cell Specialized cells DIFFERENTIATION (specializing)

Embryonic stem cells New research is looking into how to obtain stem cells from adult somatic (body) tissue and where they are located Somatic stem cells can be found in brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin, teeth, heart, gut, liver, ovarian epithelium, and testis