week 9 part 1 Flashcards
extranuclear inheritance
Transmission of genes that are located outside the cell nucleus
o Also called cytoplasmic inheritance
· Mitochondria and chloroplasts contain their own genomes
o = organelle genomes
· Organelle genomes are typically inherited maternally
o Egg cell provides most of the cytoplasm, which the much smaller male gamete provides only a nuclear genome
mitochondrial genomes
Mitochondrial genome of many mammals contains 37 genes
o 24 genes encode tRNA and rRNA needed for translation inside mitochondrion
o 13 genes encode proteins for oxidative phosphorylation
· Mutations in human mitochondrial genes can cause a variety of rare diseases that are inherited maternally
o Usually result in chronic degenerative disorders that affect brain, eye, muscle, heart, kidney, and endrocrine glands
§ Organs that required high ATP
gene linkage
When different genes are close together on the same chromosome, they tend to be transmitted as a unit
o = gene linkage
· A group of genes that usually stay together during meiosis = a linkage group
· Linked genes do not follow the law of independent assortment
linked genes
When genes are located close together on the same chromosome, the most abundant phenotypes in the F2 generation will be those with the same combination of traits as the P generation
· Nonrecombinants or parental types: offspring’s combination of traits has not changed from parental generations
o No crossing over between genes in the F1 gametes
· Recombinants or nonparental types: offspring that have a different combination of traits from parental generation
o Crossing over has occurred in the F1 gametes
linkage mapping
Recombination frequencies provide a method for mapping genes along chromosomes
o Recombination occurs less frequently between genes that are close together on the chromosome
o RF = Number of recombinant offspring/total offspring x 100
· Genetic mapping estimates the arrangement and relative distances between linked genes based recombination frequencies
· A genetic map shows the linear order of genes along a chromosome
