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BIO Exam #2 Lecture 9
Terms in this set (26)
what's Darwin's definition of evolution
darwin's definition is evolution is decent with modification
what is the modern definition of evolution
the modern definition of evolution is a change in the allele frequency of a population over time
why is the modern synthesis called " the modern synthesis"? what is it a synthesis of?
it is Darwinian evolution and it called the modern synthesis becasue it includes genetics
outline the Modern Synthesis as it was outlined in class
I. Sources of Variation
II. Agents of Change (in allele frequency)
c. genetic drift
d. non-random mating
e. natural selection
what are the two general sources of genetic variation in a populations
mutation and recombination
what is meant by the description "agents of change"? what is it that is being changed these agents?
change in allele frequencies
what are the five agents of change identified by the modern synthesis
mutation increases with ________________
why do mutations rates increase with generation time?
mutations rates increase with generation time due to increasing number of cell divisions prior to gamete formation
what is the approximate mutation rate for phenotypically detectable alleles in humans per individudal per generation?
what do we mean by phenotypically detectable?
there is some physically detectable mutation
what are the three categories of effect that mutations may have?
deleterious- 70% of mutations reduce the probability of reproducing
neutral- 30% do not alter gene resulting protein
beneficial- small minority but increase rapidily in populations via natural selection
with resepct to these three possible effects, most mutations are _____________
beneficial mutations are rare but their impact on allele frequency over time is HUGE! why?
because they increase rapidily in population via natural selection
what are five possible effects of a gene mutation?
turns it on
turns it off
creates new allele
what are two types of chromosomal mutation?
changes in Xsome structure
Changes in Xsome number
what effects may a chromosomal mutation have?
- create genes
-create reproductive isolation
what are the two types of recombination?
what is the effect of recombination
tremendous genetic variation and new combinations of traits
what kinds of mutations accumulate in a population over time?
neutral and beneficial
how/why does mutation cause populations to diverge?
the probability of the same mutations arising in different populations is v v v small
write a short, concise definition of genetic drift
random change in the allele frequencies of a population
what will happen to nuetral alleles over time
alleles not selected for or against, randomly increase or decrease over time eventually
how does genetic drift affect genetic diversity?
it always decreases genetic diversity but loss in diversity is faster as population size decreases
how does genetic drift cause population to diverge?
different alleles drift to fixation or deletion in different populations. Populations will diverge as a result of drift alone
what do we mean by a population
"bottleneck"? why is this considered an example of a drift?
greatly reduced population size causes these smaller populations to diverge faster due to reduced genetic diversity.
Recommended textbook explanations
Campbell Biology (AP Edition)
Cain, Jackson, Minorsky, Reece, Urry, Wasserman
Lehninger Principles of Biochemistry
David L Nelson, Michael M. Cox
Modern Biology: Student Edition
Janet L. Hopson, Postlethwait
Fundamentals of Biochemistry
Charlotte W. Pratt, Donald Voet, Judith G. Voet
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