Genetics+-+Applied

Sources of Genetic Variation

 * Mutations
 * Crossing-over
 * Meiosis
 * Sexual Reproduction (genetic recombination)
 * Errors in DNA replication
 * Environmental Factors

Types of Mutations

 * ** Mutation ** - a change in a gene or chromosome, or appearance of a new allele
 * ** Mutagens -** anything that causes mutations. Ex. radiation, chemicals, UV light
 * ** Chromosomal mutation -** a change in the structure of a part, or all of a chromosome, or the number of chromosomes.
 * ** Gene mutation -** affects only one gene on one chromosome
 * ** Translocation ** - the transfer of a part of a chromosome to a non-homologous chromosome
 * ** Inversion ** - part of a chromosome is rotated and reverses in order
 * ** Addition ** - a section of a chromosome breaks off and attaches to its homologous partner (gene is repeated)
 * ** Deletion ** - a section of a chromosome breaks off and is lost
 * ** Non-disjunction ** - the addition or loss of a whole chromosome. Occurs during Anaphase I of Meiosis.
 * ** Polyploidy ** - condition when cells contain multiple numbers of chromosome sets (2x, 4x, 8x). This is used to increase the size of fruit, like strawberries.
 * ** Point mutation ** - only a single nucleotide in a gene is affected
 * ** Jumping gene ** - discovered by Barbara McClintock. A gene that moves from chromosome to chromosome.

Pedigree Charts
Must be able to:
 * Used to show the passage of mutations through generations.
 * 1) tell if a disease is dominant or recessive (if the disease increases in frequency, it is most likely a dominant disease)
 * 2) tell if a disease is sex-linked (if the disease appears mostly in males, it is usually a sex-linked disease)
 * 3) identify a carrier of a sex-linked disease (look at the mother of an individual who has a sex-linked trait)

Genetic Disorders - Sex Linked

 * Color blindness - have trouble distinguishing between two different colors. Ex. red-green.
 * Hemophilia - lack clotting factors. "bleeding disease"
 * Duchenne Muscular Dystrophy - muscle tissue breaks down.

Genetic Disorders - Autosomal

 * Sickle-cell Anemia - co-dominant disorder. Those affected have abnormally shaped red blood cells. Hemoglobin production is affected. The genotypes are AS or SS. AS protects against malaria.
 * Phenylketonuria - lack an enzyme to help break down phenylalanine. If not managed, can lead to mental retardation and brain damage. Treated with a special diet.
 * Tay-Sachs - an incurable recessive brain disorder caused by a lack of an enzyme. Children live about 5 years. No cure.
 * Cystic Fibrosis - recessive lung disease; usually fatal by early adulthood. The lungs clog with mucus.
 * Huntington's disease - dominant; fatal brain disease; symptoms do not show up until after age 30.
 * Turner's Syndrome - female with only one X chromosome; sterile, underdeveloped.
 * Klinefelter's Syndrome - male with XXY; sterile, underdeveloped.
 * Down's Syndrome - caused by non-disjunction of chromosome 21. Symptoms include mongoloid eye folds, round face, small hands and feet, mental retardation, shorter life span.