Applied Genetics Aim: 1. How do mutations occur? 2. How do we get genetic disorders and how can we detect them? 3. How do scientists use genetics to improve breeding outcomes?

Sources of Variation A. Sexual reproduction brings about variation in an organism. B. Most variation is a result of segregation and crossing over during meiosis and recombination during fertilization. Others are brought about by mutations.

Mutations A. Change in the genetic material of an organism. B. Most are recessive genes and a disadvantage to an organism. C. There are 2 types of mutations: 1. Gene mutations. 2. Chromosomal mutations.

Gene Mutations A. Any change in the base pairs of an organism. B. Point mutations: involves a change in a single nucleotide.

Chromosomal Mutations A. Change in the structure of a chromosome or the number of chromosomes. 1. Changes in chromosome structure: a. Deletions - segment is lost. b. Additions - segment is gained. c. Translocation - part of chromosome breaks off & reattaches to non-homologous chromosome. d. Inversion - part of chromosome is rotated, reversing order of gene segment.

Chromosomal Mutations

Chromosomal Mutations 2. Nondisjunction: a. Addition or deletion of WHOLE chromosomes. b. Occurs when chromosomes that normally separate during meiosis stay together. Example: Down Syndrome Gametes 23 47 24

Chromosomal Mutations 3. Polyploidy a. Condition in which cells have some multiple of the normal chromosome number. b. Common in plants and rare in animals. c. Produces larger fruit. Gametes 2n 3n n

Mutagens A. Factors in the environment that cause mutations. 1. X-rays 2. Radiation - ultraviolet light, radio active substances, cosmic rays. 3. Chemicals - carcinogens (formaldehyde, benzene, asbestos).

Human Genetic Disorders A. Phenylketonuria (PKU) 1. Recessive inherited disorder. 2. Absence of an enzyme needed to metabolize an amino acid. 3. Can cause mental retardation. 4. Early detection will prevent this along with specific diet.

Human Genetic Disorders B. Sickle Cell Anemia 1. Recessive inherited disorder. 2. Abnormal hemoglobin molecule cause RBC’s to be sickle shaped. 3. Difficulty in carrying oxygen to body cells.

Human Genetic Disorders C. Tay-Sachs Disease 1. Recessive disorder. 2. Lack a specific enzyme for the breakdown of lipids in the brain. 3. Causes lipids to build up in brain cells & destroys them.

Human Genetic Disorders D. Cystic Fibrosis 1. Recessive allele. 2. Disorder which causes some glands to produce a thick mucus that clogs & damages lungs.

Detecting Genetic Disorders A. No treatment or cure is known for many genetic disorders. However, people who carry them can be tested. 1. Pedigree a. One’s family history represented by a diagram that shows the presence or absence of a particular trait in each member of each generation.

Detecting Genetic Disorders 2. Karyotyping a. Technique used to detect chromosome abnormalties. b. Chromosomes from a body cell undergoing mitosis are taken. c. Made visible in enlarged photograph & homologous pairs are matched. d. Abnormalties in chromosome structure are visible.

Detecting Genetic Disorders 3. Amniocentesis a. Technique used to detect genetic abnormalties in a fetus. b. Removal of amniotic fluid surrounding the fetus which contains fetal cells. c. Cells are analyzed for genetic abnormalties either chemically or by karyotyping.

Biotechnology A. The science that uses both biological discoveries and new technological procedures. Nick koutouvidis B. Breeders use this knowledge to improve the quality of animals and plants to produce and maintain desirable traits.

Breeding Methods A. Knowledge of genetics is used to produce organisms with desirable traits. 1. Selective breeding (artificial selection) - individuals with desirable traits are mated to produce offspring with those traits. 2. Inbreeding - offspring with desirable traits are mated with one another to obtain & reinforce those traits.

Breeding Methods 3. Out-breeding - when 2 close species both with desirable traits are mated. Offspring possess desirable traits from both parents. 4. Mutations - natural occuring mutations that express desirable traits. To ensure the trait is carried on breeders use vegetative propagation. Example: seedless grapes, seedless watermelon

Cloning A. Process of producing genetically identical offspring from a body cell of an organism. 1. One purpose of cloning is to produce large numbers of genetically identical animals for research. Example: sheep, kittens, frogs 2. Cloning that occurs in nature is mitosis and asexual reproduction.

Genetic Engineering A. Process by which genes are removed from one organism & added to the genetic material of another organism. 1. The new organism can then produce new proteins & changed DNA is called recombinant DNA. 2. Genetic engineering has helped in treating diabetes in humans by inserting the gene for making insulin into the genetic material of a bacteria. In turn, the bacteria produce insulin which can be used for treatment.