AP BIOLOGY CHAPTER 15 notes

Mapping genes n Crossing over happens more often to certain alleles that are far away from each other on the chromosome n The distance is designated by the number of map units separating the two genes.

Example of mapping genes

arkin/genetics2153/GENET10.pdf

Multiple Gene effects Pleiotropy: The ability of one gene (one protein) to affect an organism in many ways (multiple traits). Ex. Sickle-cell anemia has many symptoms Epistasis: One gene affects the expression of a gene at a different locus. (2 genes -  one trait: nonadditive) Ex. One gene in Labrador determines whether the dog deposits a lot of melanin or a small amount of melanin, Another gene determines whether the melanin will be deposited at all. If the second gene is recessive, the Labrador has no melanin independent of the first gene. Polygenic inheritance: The additive effect of two or more genes on a trait. Ex. Several genes are involved in skin color with an additive effect on the amount of pigment.

Nature vs. Nurture Are we a product of our genetics or our environment? Phenotype is not rigid and has a general “range” due to our genetics. Bell curve

Pedigree Pedigree: A family tree for a particular trait used to indicate family history. Carriers: Individuals that are heterozygous for a particular negative trait. The individual doesn’t have the trait, but they carry one bad gene that could be potentially passed onto offspring.

Pedigree

Barr Bodies One of each X chromosome is inactivated. The inactivated X is called a Barr Body. Calico cats are produced by inactivating different X chromosomes in different regions of the cat

More terms Linked genes: Genes on the same chromosome, thus they are inherited together. Sex-linked genes- Genes found on the sex chromosomes. Recombinants- Organisms resulting in the sharing of DNA from two different organisms. (sexual reproduction)

Mitochondrial DNA: All from mom in her egg