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Biology 121 > Sheet 14--Final Exam > Flashcards

Sheet 14--Final Exam Flashcards

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1
Q

What is balancing selection, and what is balanced polymorphism?

A

balancing selection–number of selective processes by which multiple alleles are actively maintained in the gene pool of a population at frequencies above that of gene mutation

balanced polymorphism- situation in which two different versions of a gene are maintained in a population of organisms because individuals carrying both versions are better able to survive than those who have two copies of either version alone—-This is maintained through balancing selection

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2
Q

what is frequency dependent selection?

A

fitness of a genotype depends on its frequency

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3
Q

what is kin selection and what is altruism?

A

apparent strategies in evolution that favor the reproductive success of an organism’s relatives, even at a cost to their own survival

altruism-selflessness is the principle or practice of concern for the welfare of others

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4
Q

what kinds of evidence support the existence of microevoultion?

A

.

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5
Q

what is industrial melanism?

A

darkness—of the skin, feathers, or fur—acquired by a population of animals living in an industrial region where the environment is soot-darkened.

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6
Q

what is the best example of microevolution in human beings?

A

aids resistence with CCR5

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7
Q

why do we think that the frequency of sickle cell anemia is much higher in central africa?

A

Selective force in Africa is presence of malaria. Maintenance of allele has adaptive value in Africa

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8
Q

since sickle cell anemia is usually lethal, why hasnt it been eliminated by natural selection?

A

.

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9
Q

why do humans living in tropical regions have dark skins while those in the north have light skins?

A

.

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10
Q

What are the two general ways in which DNA is altered?

A

radiation and chemical mutagens

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11
Q

What are the 3 ways mutations arise?

A

1) DNA damage
2) chromosomal Rearrangement
3) Transposition

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12
Q

what are four types of mutations?

A

1) point mutations–base changes
2) small deletions or insertions– frame shifts
3) large deletions or insertions
4) rearrangements of large pieces of DNA

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13
Q

What are point mutations?

A

involve small numbers of bases

  • -can include base substitutions and indels–both insertions and deletions
  • -affect one gene
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14
Q

what is an indel?

A

short way to refer to insertions or deletions

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15
Q

what are base substitution mutations?

A

chagne in the base that results in:

  • -change in the amnino acid sequence
  • -change in the stop codon
    • add or remove an intron splice site
  • –substitution is a type of point mutation
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16
Q

what are indels? what are they lumped together?

A
  • -mutations resulting from an insertion or a deletion of bases
  • -causes a frameshift
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17
Q

why are indels usually more deleterious than base substitutions?

A

indels change the entire message
–CAT CAT CAT
—-remove A
CTC ATC ATC

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18
Q

What are the two ways DNA gets damaged?

A
  • -mistakes during DNA replications

- -chemical decomposition

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19
Q

what sorts of spontaneous mutations occur during and what occur after DNA replication?

A

During DNA replication:

  • –mispaired bases
  • – misaligned bases

After DNA replication:

  • -Deaminatino of C to U
  • -depurination–loss of A or G
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20
Q

what are the two classes of mutagens?

A

radiation and chemicals

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21
Q

what sorts of mutations are caused by X-Rays?

A

double stranded breaks cause deletions, insertions, and rearrangements

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22
Q

What mutations are cuased by sun tanning?

A

UV causes formation of thymine dimers

–point mutatinos

23
Q

what sorts of mutations are cause by cigarette smoke?

A

base substitution

24
Q

what sorts mutations caused by intercalating chemicals?

A

insert into DNA and cause frame shift mutations

25
Q

what are the 3 ways that genetic recombination can alter hereditary information?

A

1) chromosomal rearrangement
2) gene transfer
3) transposition

26
Q

how can chromosomes get rearranged, and how can this chagne the genetic information?

A

Rearrangement of chromosomes is due to:

  • -unequal recombination during crossing over
    • improper repair of broken chromosomes including inversions
  • -translocatinos, deletions, insertions

Genetic information is changed due to:

    • mutations
  • -information placed in a new setting; informations is added or lost
27
Q

how can genes get transferred between organisms?

A

transfer of plasmids

–viruses- add their genome to host genome

28
Q

how can plasmids get transferred between bacteria?

A
  • -bacteria copy of plasmid
  • -sex pilus forms conjugation bridge
  • -bacteria can also pick up naked DNA
29
Q

how can viruses transfer genes?

A

viruses insert their viral genome into the host DNA

30
Q

what are the two classes of transposons, what is the main difference between them?

A

Transposons– mobile piece of DNA, inserts into genes at random, the insertion is one of most significant causes of mutation
types:
1) simplest transposons (insertion sequence)
—transposase gene and its recognitino sequence
—frequently get more complicated
———acquire drug resistanec genes and move into plasmids

2) retro viruses (nucleic acid is RNA)
- —resemble retro viruses; some genes and lifestyle
- —make RNA copy
- –revese transcriptase makes DNA copy of RNA
- -integrase inserts DNA copy at new site of host DNA

31
Q

why do we think that retrotransposons and retro viruses are closely related?

A

same genes and lifestyle

  • -use reverse transcriptase to make DNA copy
    ex. HIV
32
Q

why do transposons cause mutations?

A

insert into genes; encoded protein has a large meaningless chunk inserted into it, disrupting its structure
—this is insertional inactivation

33
Q

why do we distringuish between evolution of genes and evolution of genomes?

A

genome contains many elemets other than genes, often coding sequences are less than 5% of genome

34
Q

what are the 3 classes of human DNA sequences, and what do you find in each class?

A

1) highly repeated sequences (satellites)
- –code for nothing
- –millions/cell
- –make chromosomes longer
- –found near centromere or ends of chromosomes(telomeres)

2) moderatly repeatd sequences
- -thousands/cell
- —–a) transposons
- —–B) structural
- ———–centromeres
- ———–matrix attachement: DNA sequence to attach extended loops to scaffold
- ———–telemoeres protect chomosome ends
- ——C) multigene families: histones
- —–D) microsatellites==excess cause many diseases (used for human DNA/fingerprinting because vary alot)

3) unique= most genes

35
Q

What are the structural elements, and what kinds of structural elements do we find in genomes?

A

centromeres

–scaffolding attachment regions

36
Q

what are microsatellites and how can they affect humans?

A

nucldeotide repeats, sometimes 6-30 or 20-200

–excess cause disease

37
Q

what is copy number variation and why is it important to human health?

A

individual humans differ gentically by 10 million base pairs

  • -these frequently has to do with the number of copies of a certain gene then have in tandem
  • -susceptibility to many disease, includng aids, has been correlated with the number of copies of particular genes
38
Q

what is the difference between macroevoultion and micro evoultion?

A

Macroevoultion– formation of new species gradual
–due to microevoultion

Microevoultion– chagne in the frequencies of alleles in a population over time

evoultion– the change in the frequencies of alleles in a population over time

39
Q

what is a population and why must we study population to understand evoultion?

A
  • -group of individuals of same species in same area, can interbreed
  • -populations evolve, not individuals
40
Q

what is population genetics?

A

study of how genes behave in a population?

41
Q

what is a gene pool?

A

sum of all alleles in all individuals in the population

42
Q

why do populations geneticists measure allele frequencies and how do they measure them?

A

chagne in allele frequencies= evoultion

–use Hard Weinberg equilibrium

43
Q

Why is Hardy weinberg equibrium rarely achieved and why is it useful?

A

it predicts equibrium–no change, no evoultion
–this never occurs in nature

Useful:

  • -population geneticists compare observed frequcies with those predictd by H-W to identify whats happening
  • -this provides a starting point for studying changes in the gene pool of a population
44
Q

what are 5 main causes of microevoultion, which of these factors is most likly to be adaptive?

A

1) mutation
2) migration (gene flow)
3) genetic drive
4) non random mating
5) natural selection–*most adaptive

45
Q

what is genetic drift and what is the differenec between genetic drift and gene flow?

A

genetic drift

  • -changes in allele frequency in small population
  • -small isloated population become very differnt (random)
  • -includes founder principle and bottleneck effect

Gene flow= migration: movement of individuals from one population to another

  • -alters composition of gene pool
    • tends to homogenie allele frequency in populations
46
Q

difference between founder effect and genetic bottleneck?

A

founder effect:

  • -few individuals start a new, isloated populations
  • -an allele that is rare in source population may become significant new population
  • -important in oceanic island evoultin

bottleneck effect:
–populations randomly greatly reduced in size
– surviving individuals represent random genetic sample of orginal population
ex cheetahs

47
Q

why is inbreeding an unwise practice?

A

homozygosity–increases liklyhood of genetic disorders

48
Q

why are many breeds of pure bred dogs “going to the dogs”

A

difficult to predict genetic outcomes

49
Q

what is hybrid vigor?

A

heterozygote is better adapted than either parent

  • -useful in corn breeding for example
  • AA x aa=Aa
50
Q

How does heritable variation arise?*

A

mutation and recombination

51
Q

which of the following mutations is most likely to be lethal to an organism?

A

deletion of a single base near the start of a coding sequence

52
Q

why do many retrovirses cause cancer?

A

they have added and oncogene from a former host to their genome, which they then add to the genome of each new host

53
Q

what is the difference between microevoultion and macroevoultion?

A

microevoultion is changes in the populations gene pool, macroevoultion is formation of a new species

54
Q

beardless females?

A

square root of 0.01

Biology 121 (9 decks)

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