Test 4 Flashcards
(63 cards)
1
Q
2 Types of Mutations
A
- Point Mutation
- Chromosomal Mutations
2
Q
Point Mutation
A
- change in a nucleotide in a DNA sequence due to an error in replication
a) silent mutation
b) missense mutation
c) nonsense mutation
d) frameshift mutation
3
Q
silent mutation
A
- error does not change the amino acid that is coded for
4
Q
missense mutation
A
- error that does change the amino acid that is coded for
i) neutral - does not alter protein function
ii) negative - reduces protein function
iii) positive - enhances protein function
5
Q
Frameshift mutation
A
an extra nucleotide is added or removed
6
Q
Nonsense mutation
A
results in early stop codon
7
Q
Chromosomal Mutations
A
- changes in chromosomal number or structure
- changes in chromosomal number would be anueploidy or polyploidy
8
Q
Chromosomal Mutation - Change in Structure
A
- duplication
- deletion
- translation
inversion
9
Q
Duplication mutation
A
- a segment from one chromosome is transferred to its homologous chromosome, giving it a duplicate of some genes
10
Q
Deletion mutation
A
- a chromosome segment is lost
11
Q
Translocation mutation
A
- a segment from a chromosome is transferred to another chromosome
12
Q
Inversion mutation
A
- occurs when a chromosome breaks in 2 places
- segments are reversed and re-inserted into chromosome
13
Q
What are the most problematic chromosomal mutations?
A
inversion and translocation
14
Q
Evolution
A
change in the allelic frequencies of a population over time
15
Q
Darwin’s 5 Observations
A
1) in nature there are more individuals born to a population than wii survive to reproduce; the struggle for existence
2) most populations tend to stay the same year to year; struggle for existence
3) there is heritable variation in traits within populations: differential reproductive success
4) some trait variants allow their precessor to be more successful at surviving and reproducing; differential reproductive success
5) those trait variants will become more common in future generation; evolution
16
Q
Evolution by Natural Selection
A
- change in allelic frequencies of a population over time due to differential reproductive success that is based on heritable variation within a population
- requires:
a) heritable variation
b) differential reproductive success
17
Q
heritable variation
A
- mutations
- sexual reproduction (crossing over and independent assortment)
18
Q
differential reproductive success
A
the idea that some individuals in a population produce more offspring than others due to differences in traits that affect survival and reproduction; leads to traits becoming more common in the population over time
19
Q
Fitness
A
- the number of copies of an individual’s genes in future generations
- function of quantity and quality
20
Q
4 Modes of Natural Selection
A
1) Stability selection
2) Directional Selection
3) Disruptive Selection
4) Balancing Selection
21
Q
Stability Selection
A
- acts to maintain allelic frequency in the population bc the mean phenotype is the most fit
- most common
22
Q
Directional Selection
A
- acts to make one extreme of the phenotypic range more common because that portion of the range is more fit
- change in environment
- once it reaches limit it becomes a stability selection
23
Q
Disruptive Selection
A
- acts to divide the population into 2 or more genetically distinct races bc the extreme phenotypes are more fit than the mean
24
Q
Balancing Selection
A
- acts to maintain genetic diversity in the population by:
a) heterozygotes are the most fit
b) frequency dependent selection
25
Other Mechanisms of Evolution
1. mutations
2. gene flow
3. genetic drift
4. non-random mating
26
Gene Flow
- movement of alleles into or out of populations
27
Genetic Drift
- random events prevent some individuals in a population from reproducing, so population loses genetic variability
a) population bottleneck
b) founders effect
28
Population bottleneck
- catastrophic event wipes out a significant portion of the population
29
Founders effect
- a small subset of parent population emigrates and forms a new population
- new population is a genetic subset of parent population (genetically different from parent generation)
30
Non-random mating
a) forced inbreeding
b) sexual selection
31
Forced inbreeding
- small isolated populations
- low offspring dispersal rate
leads to inbreeding depression
32
Inbreeding depression
- reduction in fitness caused by mating with close relative
- enhanced expression of negative allele (recessive allele)
33
Sexual selection
- directional selections that acts differently on the 2 sexes due to differences in reproductive potential of the sexes
34
Reproductive potential
- the potential number of offspring of an individual
females: determined by the number of eggs she can make; limited bc eggs are expensive to make
males: determined by the number of eggs fertilized
- results in dimorphism
35
Reproductive Traits for Females
- traits that enhance quantity (limited)
a) ability to get energy
b) size - affects fish and arthropods
- traits that enhance quality (natural selection works hard here)
a) female choice (choosing a high quality male)
36
Reproductive Traits for Males
- traits that enhance quantity (natural selection works hard here)
a) being attractive to the female
b) competitive ability
- traits that enhance quality
a) being attractive to the female
b) competitive ability
37
Dimorphism
- non-gonadal (not related to sexual reproduction organs) differences between the sexes
- 3 versions
1) females are larger than males
- female fecundity increases with body size
2) males are larger than females and have weapons
- male to male competition for access to females
3) males exhibit elaborate secondary sexual characteristics (ESSC)
- females choose their mates
38
2 Explanations for the evolution of ESSC's (elaborate secondary sexual characteristics)
1) handicap hypothesis
2) sensory exploitation hypothesis
39
Handicap Hypothesis
- natural selection favors females that are attracted to bright/bold things
- those 'things' serve as an honest signal of male genetic quality
40
Sensory Exploitation Hypothesis
- characteristics evolve because they take advantage of innate (genetically programmed), often unexpressed preferences in females
41
Speciation
the evolution of one or more species from a parent species
42
Biological Species Concept
- a species is a group of actually or potentially interbreeding populations that is reproductively isolated from other groups
- limited to sexually reproducing organisms
43
Interbreeding
- the ability to breed with another race or species and produce viable offspring
44
2 Steps in Speciation
1. extrinsic isolation
2. intrinsic isolation
45
Extrinsic isolation
something happens to block gene flow between 2 populations of the same species
46
Intrinsic Isolation
- eventually the 2 extrinsic populations evolve to be so different from each other, that they lose the ability to interbreed, should the extrinsic barrier go away
47
Intrinsic Isolating Mechanisms
- differences that could arise to remove the potential to interbreed
- 2 versions:
Prezygotic Mechanisms
Postzygotic Mechanisms
48
Pre-zygotic mechanisms
1. Mechanical
- differences in the reproductive structures
2. Temporal
- changes in the timing of reproduction
3. Habitat
- change in habitat used for reproduction
4. Behavioral
5. Gametic
- sperm from one population cannot fertilize eggs from another population
49
Post-zygotic mechanisms
1. zygote doesn't develop
2. non-viable offspring
50
Extrinsic Isolating Mechanisms
- stops gene flow between 2 populations
- 2 versions:
Allopatric speciation
Sympatric speciation
51
Allopatric Speciation
- some physical barrier "arises" to stop gene flow from occurring between 2 populations
-2 versions:
a) vicariance
- physical barrier arises
b) dispersal
- one population disperses to a different area
52
Sympatric Speciation
- gene flow is halted between 2 segments of a population that co-occur in the same area
- most common in phytophagous (plant-eating) insects
- tend to be very species specific
- disruptive selection or polyploidy
53
Taxonomy
- represents the way organisms are related to each other
54
Systematics
- the study of evolutionary relationships of the organisms
- tools of systematists:
a) fossil record
- transitional fossils
b) homologies
- traits shared by different species that points to a common ancestor
55
Types of homologies
1. structural
- physical traits shared by different species in adulthood that point to a common ancestor
2. embryonic
- traits shared by different species during the embryonic stage that point to a common ancestor
3. genetic
- similarities in highly conserved genes
- similarities in non-coding DNA
- pseudogenes ( genes that have mutated so that they cannot be expressed)
4. vestigal structures
- reduced non-functional structures left over from an ancestor
56
Convergent Evolution
- distantly related, but ecologically similar species evolve to have similar traits
57
Human lactoferrin
- protein
- immune system enhancer
58
3 steps used to make herman
1. isolate gene
2. clone gene
3. inject gene into cow
59
Isolating the gene
- tissue sample from an organ donor from a lactating female that is actively expressing the HLF gene is put in a test tube and digested with lipase and protease
- it is the suspended in ethanol and put in a centrifuge
- pellet of nucleic acids settles to bottom
- pellet is suspended in water
- solution is ran through a poly t column; DNA, tRNA, and RNA are thrown away; the polyA tail on mRNA is bonded to the thymines in the poly T column
- poly t column is rinsed with a weak acid and mRNA is left over
- mRNa undergoes reverse transcription (adds DNA nucleotides and reverse transcriptase) to create the HLF gene
60
Cloning the HLF gene
uses 2 tools from bacteria
1. plasmid
2. restriction endonuclease
61
Plasmid
- small circular outer bit of DNA found in some bacteria
- not essential
- contains genes that can get replicated
- from the environment or other bacteria
62
Restriction Endonuclease
- enzyme that binds to sections of DNA that have a specific nucleotide sequence and cuts DNA at that location
- bacterial DNA is methylated and prevents the enzyme from cutting it
63
What is EcoR1?
a restriction endonuclease derived from E. Coli used to cut viral DNAs and plasmids forming sticky ends that are easy to ligate
