Variation and Inheritance Flashcards

Question

what is recombination?

Answer 1

a source of genetic variation! recombination shuffles existing variation into new combinations creating new combinations leads to greater levels of phenotypic variation

Answer 2

mutation is the ultimate source of all heritable variation! ex. unequal crossing over alters larger sections of DNA

Answer 3

RANDOM new mutations/recombinations have no inherent tendency to result in adaptation --> they are random with respect to adaptation***** given that organisms are adapted to begin with, these changes are more likely to be nonadaptive or even maladaptive but...mutations and recombinations can be nonrandom at the molecular or chromosomal level because certain nucleotide substitutions are more likely than others

Answer 4

mutation acts on existing genes, modifying or generating new alleles impact can be large or small: - mutation in regulatory gene can cause early death - redundancy in genetic code means not every substitution specifies a new codon (silent mutations)

Answer 5

NOTHING mutations happen because of sloppy copying, DNA degradation, and random processes although mutations are generated through random processes, they may not be propagated/inherited randomly

Answer 6

although mutations are generated through random processes, they may not be propagated/inherited randomly The mutation that provides resistance to antibiotics in bacteria is generated randomly. Its spread through the population is NOT random, though—it is a predictable response to a set of circumstances same goes for pesticides

Answer 7

both alleles are expressed, and the heterozygote manifests a third phenotype with properties of both alleles ex. blood types!!!! NOT blending - heterozygotes lets the A allele and the B allele exist simultaneously in your blood

Answer 8

Heterozygote results in a third unique phenotype. Alleles are “blended”together ex. Red and white flowers produce a heterozygous pink flower looks like blending but really what's happening is that the heterozygous is expressed in a third phenotype rather than one or the other

Answer 9

1) pleiotropy | 2) epistasis

Answer 10

when a single gene impacts two or more seemingly unrelated traits one gene mutation effects two alleles! ex. Holt-Oram: defective allele for TBX5 causes malformation of upper limbs and abnormal septa in heart

Answer 11

when one gene interferes with the expression of another gene Many genes interact to make skin color, eye color, hair color  if you’re recessive at a specific gene (albino gene) then all color producing genes are shut off this happens because albinism alleles disrupt production of melanin pigment and other phenotypes are not distinguishable without melanin

Answer 12

pleiotropy: one gene wit multiple phenotypic effects epistasis: two genes contribute to one phenotype

Answer 13

several genes may make products that contribute to a phenotype --> MULTIPLE genes each with multiple alleles all interacting to produce a phenotype ex. at least 3 genes determine eye color Traits that display a continuous distribution, such as height or skin color, are polygenic. The inheritance of polygenic traits does not show the phenotypic ratios characteristic of Mendelian inheritance, though each of the genes contributing to the trait is inherited as described by Gregor Mendel.

Answer 14

non-genetic factors genotype is expressed in the context of its bearer --> this is what is meant by environmental cause of variation! nature vs. nurture

Answer 15

anything in the environment that induces variation in the population the environment in which organisms grow and mature determines the degree to which genetic "potential" is realized ex. temperature within a turtle nest determines sex ex. you have the genes to be that tall but your environment limited you to being not as tall

Answer 16

maternal effects anything mom is doing can have effects on the embryo and can have post-birth effects too  mom is an environmental effect!!!!!!! She is in no way altering the genome of the baby ex. environment of womb/egg, amount of yolk in egg, post birth maternal care

Answer 17

Variation due ONLY to environmental effects is NOT a factor in evolution

Answer 18

1) controlled crosses 2) common garden experiments 3) cross fostering

Answer 19

determine whether phenotypes are inherited according to expectations of Mendelian genetics

Answer 20

raise offspring under identical conditions and run several "gardens" to test effect of particular variables

Answer 21

common gardens for animals but the offspring are raised by parents other their own

Answer 22

Vp = Vg + Ve ``` Vp = phenotypic variation Vg = genotypic variation Ve = environmental variation ```

Answer 23

heritability is the proportion of variation that can be attributed to genotype *h^2 = Vg/Vp* heritability is high when Ve is low indicated fidelity of trait transmission and thus how readily evolution can act on an attribute

Answer 24

h^2 determines the response to selection higher h^@ means stronger response to selection! if a trait is perfectly heritable, h^2 = 1, then ALL of the impact of selection will be observed