7: Mutation, Repair, & Transposable Elements Flashcards

0
Q

Adaptive mutation hypothesis

A

Environment causes heritable change

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1
Q

What is the spontaneous random mutation hypothesis?

A

Mutation occurs by chance and not in response to the environment

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2
Q

What did luria and delbruck do?

A

They performed a fluctuation test, disproving the hypothesis of adaptive mutation

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3
Q

Mutation rate =

A

Change/nucleotide/generation

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4
Q

Eukaryotic mutation rate

A

10^-4 and 10^-6

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5
Q

Bacteria/phage mutation rate

A

10^-6 and 10^-8

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6
Q

Transition mutations

A

Purine –> purine

Pyrimidine –> pyrimidine

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7
Q

Transversion mutations

A

Pyrimidine –> purine

Purine –> pyrimidine

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8
Q

Is transition or transversion more common?

A

Transition

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9
Q

What is a missense mutation?

A

A change from one amino acid to another

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10
Q

What is a nonsense mutation?

A

A change from an amino acid to a stop codon

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11
Q

What is a neutral mutation?

A

A change from an amino acid to another amino acid with similar chemical properties

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12
Q

What is a silent mutation?

A

A change in the codon such that the same amino acid is coded for

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13
Q

2 types of reversion mutations

A
  1. True reversion

2. Partial reversion

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14
Q

True reversion

A

Mutant to wild type ( identical amino acid seq)

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15
Q

Partial reversion

A

Changes in other amino acid that fully or partially restores protein function

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16
Q

suppressor mutations

A

Occur at sites different from the mutations they suppress

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17
Q

Intragenic suppressor

A

A suppressor that occurs within the same gene as the original mutation, but at different sites

18
Q

Intergenic suppressor

A

At mRNA translation level

Each suppressor works on only one type of nonsense, missense, or frameshift mutation

19
Q

Nonsense suppressors

A

In redundant tRNA genes

Occurs by competition between release factor and suppressor tRNAs

20
Q

At which phase of the cell cycle do mutations occur?

A

S phase

21
Q

7 factors that effect mutation rate

A
  1. Spontaneous isomerization due to reversible proton shift
  2. Base analogs
  3. Genetic constitution of organism
  4. Repetitive nucleotides, cg islands, pyrimidine dinucleotides
  5. DNA polymerase proof-reading functions
  6. DNA repair
  7. Selection
22
Q

Base substitution

A

Enol OH can form H bond w/ incorrect partner

23
Q

Which nucleotide does G wobble base pair with?

A

T

24
Q

Deamination of cytosine results in…

A

Uracil

25
Q

What is a mutation hotspot?

A

5-methyl-CG regions

26
Q

What is DNA methylation?

A

Addition of a methyl group to C and A

27
Q

What uv range is absorbed by purines and pyrimidines?

A

254-260 nm

28
Q

What is the cumulative effect?

A

A particular dose of radiation results in the same number of mutations whether it is received over a short or long period of time

29
Q

What do x-rays do to DNA?

A

They break covalent bonds

30
Q

What are base analogs?

A

5-methyluracil and 5-bromouracil. Analogs of thymine that change what it pairs to

31
Q

What are 3 base-modifying agents?

A

Nitrous acids, hydroxylamine, and methylamine sulfonate

32
Q

What is an intercalating agent?

A

Mutagen allowing for insertion

33
Q

What is the ames test?

A

A test to screen for potential carcinogens using Salmonella typhimurium

34
Q

What is the mutD gene?

A

A subunit of DNA polymerase III with proofreading functions

35
Q

What is Xeroderma pigmentosum?

A

A disorder that occurs in homozygotes for a mutation in 1 of 9 repair genes

36
Q

Where are retrovirus type transposons found?

A

Only in eukaryotes

37
Q

What are insertion sequences?

A

The simplest transosable elements made up of a transposase gene and inverted repeats. They are randomly integrated.

38
Q

What is a byproduct of IS insertion?

A

Small direct repeats

39
Q

What are composite transposons?

A

Transposons that carry antibiotic resistance genes flanked by IS elements. Tranposition results from IS. They cause target site duplication.

40
Q

What are noncomposite transposons?

A

Transposons that carry drug resistance genes but do not terminate with is elements but with repeated sequences. They cause target site duplication.

41
Q

What are p-elements?

A

Transposons that make up 15% of the drosophila genome

42
Q

What are LINEs?

A

Autonomous retrotransposons with functional transposition genes. 20% of the genome

43
Q

What are SINEs?

A

Non-autonomous retrotransposons