Genes in populations Flashcards
what are causes of mutations in genes?
radiation, UV, X ray
what is the source of all genetic variation?
mutation
what is polyploidy?
3 or more times the haploid chromosome number
what is aneuploidy?
one set of chromosomes is incomplete
what is nullisomy and its effects?
both members of a pair of chromosomes are missing and it is lethal
what are translocations?
exchange of parts between non homologous chromosomes
what is an inversion and its effect?
a balanced rearrangement often with no effect only maybe in meiosis
what is the difference between synonymous and non-synonymous mutations?
synonymous dont change the amino acid and non synonymous do
what are features of gametic mutations?
heritable, severe and can affect all cells
what are features of somatic mutations?
not heritable, usually mild and don’t affect all cells
what are mendels 3 laws?
1) the law of segregation
2) the law if independent assortment
3) the law of dominance
what is the law of segregation?
two parts of a gene segregate from each other during the formation of gametes
what is the law of independent assortment?
the alleles of different genes segregate independently of each other
what are exceptions to the law of independent assortment?
the closer 2 genes physically are to each other the greater violation of the law
what are the 3 reasons why natural selection works?
1) individuals vary genetically
2) some variants are fitter than others
3) variation is heritable
what does blending inheritance cause?
all the offspring are the same - geneticaly uniform population
what is is it called if one gene is involved in a disease?
mendelian/monogenic disease
what is it called if more than one gene is involved in a disease?
multi factual disease
what is autosomal dominance?
- affected person has at least one affected parent and can affect either sex
what is autosomal recessive?
- affected person usually have unaffected parents and can affect either sex
what is x linked recessive?
carrier females which usually have male affected offspring
what is x linked dominant?
affects both males and females - all females of affected males have the disease
what is y linked disease?
only males are affected
what is X chromosome inactivation? (lyonization)
in each cell of females one X is randomly inactivated
what did the fruit fly experiments demonstrate?
shows that many genes lie on chromosomes - showed eye colour gene was on X chromosome
what is recombination? (crossing over)
non independent assortment of linked genes
how do you work out a recombination fraction?
add together the observed recombinant genotypes and divide by total of all genotypes
what does the recombination fraction measure?
the distance between 2 genes
what is the unit of measurement to measure distance between genes?
centimorgans
what is the evolutionary significance of recombination?
can speed up the rate of evolution producing fitter genotypes and can break up co adaptive gene combinations
