LAB 5 - Evolution Flashcards
What was Darwin’s Theory of Evolution?
populations evolve over the course of generations through a process of natural selection
What is genotype?
- genetic make-up of an organism
- set of alleles of an organism
What is the phenotype?
- determined by an organism’s genetic make-up
- and environment in which organism lives
What is a gene?
- a heritable unit that may influence a trait
- sequence of DNA
What is an allele?
- alternative DNA sequence at the same physical gene locus
- may or may not result in different phenotypic traits
What is a locus?
-site on a chromosome where a particular gene is located
What is homozygous?
-having identical alleles for a single trait
AA or aa
What is heterozygous
-having different alleles
-dominant and recessive
Aa
What is the Hardy-Weinberg equation?
p^2 + 2pq + q^2 = 1
What is p^2
freq. of homozygous dominant individuals (genotypes)
what is q^2
freq. of homozygous recessive individuals (genotypes)
What is 2pq?
freq. of heterozygous individuals (genotypes)
When does evolution happen?
-when there is a change in gene frequency within a population over time
What is fitness?
- ability for an organism (based on its genotype) to
1. survive
2. find a mate
3. produce offspring - pass to next generation
Which beetles have greater fitness relative to the other beetles?
brown beetles have greater fitness relative tot he green beetles
What are the 3 modes of natural selection?
- stabilizing selection
- directional
- disruptive
What is allopatric speciation?
different environment
What is sympatric speciation?
- new species evolve from a single ancestral species
- same geographic region
What is mutation?
-a change in the nucleotide sequence of an organism’s DNA
What is genetic flow?
- transfer of alleles from one pop. to another
- resulting from movement of fertile individuals or their gametes
What is genetic drift?
-chance events cause unpredictable fluctuations of allele frequencies from one generation tot he next
What are 5 evolutionary agents?
- mutation
- gene flow (migration)
- genetic drift
- Natural selection
- nonrandom mating
What are 2 types of genetic drift?
Bottleneck + Founder Effect
What are 2 sources of genetic variation?
- mutation
2. gene flow
What are the 5 conditions of Hardy-Weinberg Equilibrium?
- no mutations
- no gene flow
- no natural selection
- random mating
- large population
What experiment in lab was done to test incomplete vs. complete dominance?
PTC Exercise
What is PTC?
harmless chemical with a bitter taste
What is the percentage of people who can taste PTC and those who can’t?
75% tasters
25% non tasters
What does PTC resemble structurally?
toxic alkaloids found in some poisonous plants
What is an example of an autosomal recessive disorder?
sickle cell anemia
Which is the normal Hg allele?
- S allele (normal Hg, normal RBC)
- s allele (mutated Hg, sickle RBC)
What is the missense mutation?
Val instead of Glu
What are 2 molecular clocks?
- DNA sequence homology
- amino acid sequence homology
What are 5 things taht today’s species are classified by into phylogenetic taxa?
- comparative anatomy
- comparative embryology
- fossil records
- DNA sequence homology
- amino acid sequence homolgy
What is the molecular clock hypothesis based on?
theory that specific DNA sequences(or proteins they encode) spontaneously mutate at constant rates
What is the molecular clock hypothesis used to do?
- estimate how long ago two related organisms diverged from a common ancestor
- when speciation occured
What is a phylogenetic tree?
-graphical representation of the evolutionary relationship between taxonomic groups
What is a clade?
-group that includes common ancestor and all descendents
What is a clade also called?
monophyletic group
What is natural selection?
- process which fittest organisms survive, find a mate, reproduce
- phenotypes being selected
- genotypes being passed on
What is evolution?
-change in the frequency of alleles in the gene pool from one generation to the next
What is macroevolution?
- evolution above the species level
- new group of organisms arises form common ancestors through speciation events
What did Hardy and Weinberg propose?
-frequencies of alleles in a population will stay constant/not change
What is incomplete dominance?
neither alleles in heterozygote are fully expressed
EX: PTC test
What is stabilizing selection?
intermediate phenotype favored
What is disruptive selection?
favors both extreme phenotypes
What is directional selection?
favors one over the other extreme phenotypes
What does s cause?
causes RBC to become rigid and sticky
Which sickle cell alleles increase and which decrease?
S increase, s decrease
What is the molecular clock hypothesis?
- changes that occur in genetic material of isolated populations
- due to mutations that occur at constant rates
What is the result of molecular clock hypothesis?
-scientists can determine approx. point when 2 species diverged from common ancestor (when speciation occurred)
The more mismatched the pairs of nucleotides _______
- the more different these DNA sequences are
- less closely related
