Genetic's Final Flashcards
Population
A group of individuals from the same species living in a particular geographic area who can interbreed with each other
Gene pool
The collective set of all genes, including all variations (alleles), present within a population of interbreeding organisms
Genetic drift
The change in frequency of an existing gene variant in the population due to random chance.
What assumptions must be met for a population to be in Hardy-Weinberg equilibrium?
Large
Randomly mating
Not affected by mutation
Not affected by migration
Not affected by natural selection
How does the Hardy-Weinberg equilibrium change for an X-linked recessive trait?
F(X1X1 female) = p2
F(X1X2 female) = 2pq
F(X2X2 female) = q2
F(X1Y male) = p
F(X2Y male) = q
How does Positive or negative assortment mating affect genotype frequencies?
Positive assortative mating: a tendency of like individuals to mate
Negative assortative mating: a tendency of unlike individuals to mate
How does Inbreeding and outcrossing affect genotype frequencies?
Inbreeding increases the percentage of homozygous individuals in a population.
Outcrossing will result in more heterozygotes than predicted by the Hardy–Weinberg law.
How do Mutations affect genotype frequencies?
Change in allelic frequencies and equilibrium will be reached between forward and reverse mutations
Increases genetic variation within and between populations
How does Gene flow affect genotype frequencies?
(Also known as migration)
Increase genetic variation within populations
Decreases genetic variation between populations
How does Genetic drift affect genotype frequencies?
Change in allelic frequencies, fixation on one allele.
Increases genetic variation between populations
Decreases genetic variation within populations
How does the founder effect affect genotype frequencies?
Cause of genetic drift so…
Increases genetic variation between populations
Decreases genetic variation within populations
How does natural selection affect genotype frequencies?
Can increase genetic variation within and between populations
Can decrease genetic variation within and between populations
How does a genetic bottleneck affect genotype frequencies?
Cause of genetic drift so…
Increases genetic variation between populations
Decreases genetic variation within populations
What is the difference between a tumor suppressor and an oncogene? Which is usually dominant and which is usually recessive?
Oncogenes: mutated, dominant-acting, stimulatory genes that cause cancer
Tumor-suppressor genes: mutated recessive-acting inhibitory genes that are inactive
How do cell cycle checkpoints contribute to cancer development?
Progression through the cell cycle is controlled at checkpoints, which are regulated by interactions between cyclins and cyclin-dependent kinases. Genes that control the cell cycle are frequently mutated in cancer cells.
How does telomerase contribute to cancer development?
Mutations to telomerase can essentially cause a cell to become immortal.
How do DNA repair genes contribute to cancer development?
These mutations increase the rate at which mutations are retained and result in an increased number of mutations in proto-oncogenes, tumor-suppressor genes, and other genes that contribute to cell proliferation.
How does loss of heterozygosity contribute to cancer development?
If a heterozygous person loses the Dominant tumor-suppressor gene it may cause cancer.
How does the p53 gene contribute to cancer development?
Known as the “guardian of the genome”
How does the retinoblastoma (Rb) gene contribute to cancer development?
Retinoblastoma results from at least two separate genetic defects, both of which are necessary for cancer to develop. In sporadic cases, two successive mutations must occur in a single cell, which is unlikely, and therefore the cancer typically affects only one eye.
In people who have inherited one of the two required mutations, every cell contains this mutation, and so a single additional mutation is all that is required for cancer to develop. Given the millions of cells in each eye, there is a high probability that the second mutation will occur in at least one cell of each eye, producing tumors in both eyes and the inheritance of this type of retinoblastoma.
How does DNA hypermethylation contribute to cancer development?
Inhibit the expression of tumor-suppressor genes.
How does chromosome translocations contribute to cancer development?
Chromosomal instability is a general feature of cancer cells
They can cause breaks in genes that suppressor tumors.
How do retroviruses contribute to cancer development?
Mutating and rearranging proto-oncogenes
Inserting strong promoters near proto-oncogenes
