exam 3 ppt 6 Flashcards
definition of allele
one of several forms of a gene
definition of genotype
the particular combo of alleles present in a given organism
definition of phenotype
the expression of a trait in an individual
how many alleles does a diploid organism have of every gene?
a diploid organism always has 2 alleles of every gene
what are the alleles like in a homozygous genotype?
both alleles for a given trait are the same (ex: TT or tt)
definition of evolution
a change in characteristics of a population over time- species are related to one another and can change through time
definition of population
individuals of the same species that live in the same area at the same time
definition of natural selection
one way evolution occurs; individuals with beneficial traits are more reproductively successful
2 types of variation
environmental, genetic
which type of variation is more important for evolution?
genetic
is mutation adaptive?
no
what causes genetic variation?
mutations (during cell division), recombination/independent assortment/crossing over
does evolution occur with phenotypes produced by the environment?
no, only genetic differences
definition of population genetics
the study of genetic variation in natural populations; changes in genotype and allele frequency over time
sections of mutation variation
somatic, germ-line (during cell division)
sections of recombination variation
(in meiosis I); deleterious (harmful), neutral (silent), advantageous -> adaptation
what does natural selection govern?
itgoverns that variants best suited for growth and reproduction contribute more to future generations
allele frequency=
of copies of an allele / total # of alleles in the population
genotype frequency=
of individuals with a genotype / total # of individuals in the population
definition of gene pool
sum of all alleles in a population
what is the limit for allele frequency?
can only be between 0-1
when is a population fixed for an allele?
when a population exhibits only one allele, it is fixed for that allele
how do we measure allele frequencies?
phenotype (observable traits), DNA sequencing
do individuals evolve?
no- populations evolve, not individuals
definition of evolution
a change in genetic makeup of a population over time (change in allele or genotype frequency)
are any changes in genetic makeup- allele or genotype frequencies- evolution?
yes
hardy-weinberg equilibrium basic equation
p + q = 1
in HWE, p =
dominant allele
in HWE, q =
recessive allele
HWE uses the same principles as punnett squares to predict genotype frequencies at the ______ level
population
HWE extended equation
p^2 + 2pq + q^2 = 1
