lec 12- genetics Flashcards
mutations in the germ line (ovaries and testes) can be passed to what?
the next generation
are mutations of somatic cell lines passed on?
no, but can have major consequences for individuals
if mutation rates for a gene are low, why do they happen so commonly?
because of genome size, like 3 billion base pairs in a genome increase chance of mutations
what does selection and drift act on?
mutations
what is cancer?
-the uncontrolled division and proliferation of a population of cancerous cells, ultimately causing tissue and organ damage
-usually regulated, but some protooncogenes mutate and turn into cancerous oncogenes
how do cancer populations evolve?
-chemotherapy kills off original cancer cells and produces a remission, but new mutations appear in the survivors which increase the new variants populations
-that is why early diagnosis and treatment are important
what is recombination during prophase?
-when in meiosis 1, paternal and maternal autosomes (somatic chromosomes) cross over, where they share genetic material with each other
what is synapsis?
the fusion of non-sister chromatid arms
are offspring chromosomes uniquely different compared to parents?
yes, due to recombination
what is independent assortment during prophase?
random shuffling of maternal and paternal chromosomes in a gamete
for 23 pairs of chromosomes 2^23 = 8,888,608 combinations
for 3 2^3 = 8 combinations
how does meiosis generate unlimited genetic variation?
through recombination and independent assortment
can variation be hidden in genes?
yes if there is a recessive gene
what is a genotype?
the genetic makeup of an individual
what is a phenotype?
observable measurable characteristics of an individual
what does the polyphenic trait in aphids do and what triggers it?
-the same genotype produces either winged or wingless aphids, depends on environmental signals: 2 genetic pathways can be triggered
-crowding trigger for wings, promotes dispersal
what is a polyphenic trait?
single genotype produces multiple phenotypes depending on environment
are quantitative traits like height influenced by genes and the environment?
yes
what is phenotypic plasticity?
the ability to change phenotype in response to environment
what are continuously varying traits also known as?
quantitative traits
how was Darwin limited when it came to genetics?
-he knew traits were inherited, but not how due to not knowing about DNA and genes
- Mendel showed that traits are inherited by predictable ratios through dominant and recessive alleles
what is population genetics?
the study of allele (alternate forms of gene) frequencies and their changes in a population
under what conditions does the Hardy-Weinberg principle occur?
under conditions where genetic change cannot occur
under what conditions will a population’s allele frequency not change according to hardy-Weinberg?
-population is infinitely large
-different genotypes do not differ in fitness
-there is no mutation within gene pool
-mating is random for the gene locus
-there is no gene flow
rare conditions in nature
what are the two things geneticists are interested in when it comes to HWT?
- gene (allele) frequencies = relative abundance of p and q
- genotype frequencies = frequency of possible combinations of the same allele
what is the HWT equation?
p^2 + 2pq + q^2 = 1
p + q = 1
