Module 10 Flashcards

1
Q

Point Mutations

A

Can be in the form of a missense, nonsense, silent, or frameshift mutation

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2
Q

Gene mutations outside coding regions:

A
  • Promoter
  • Regulatory element
  • 5’/3’-UTR
  • Splice recognition sequence
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3
Q

Position Effect

A

An alteration in the expression of a gene after it is transposed (changes position), it may either assume the expressivity of another gene under which promoter it lands under, or it may not be expressed if moved to heterochromatin/inactive sequence

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4
Q

Germ Line Mutations

A

Can occur directly on an egg or sperm cell, affects the entire zygote

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5
Q

Somatic Cell Mutations

A

Can occur within a single embryonic cell, as that cell proliferates a patch develops with the mutation

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6
Q

Lederberg & Lederberg Experiments

A

Studied resistance of E. coli to bacteriophage T1, discovered tonr gene conferring resistance only from specific colonies repeatedly, which supported their random mutation hypothesis

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7
Q

Spontaneous Mutations

A

Mutations with intracellular causes (ex. DNA replication errors)

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8
Q

Induced Mutations

A

Mutations caused by environmental agents (ex. chemical or physical mutagens)

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9
Q

Examples of Spontaneous Mutations:

A
  • Depurination (removes purines, forming apurinic sites)
  • Deamination (removes amino group from cytosine, which becomes uracil or thymine)
  • Tautomeric Shift (T and G can convert to enol, A and C can convert to imino)
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10
Q

Trinucleotide Repeat Expasion (TNRE)

A

Causes some human genetic disease above a length limit for carriers, contain C and G and form hairpin during replication which lengthen the DNA strand

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11
Q

Mutagen

A

Agents altering DNA structure and causing mutations

Can be physical (ex. ionizing and non-ionizing radiation) or chemical (ex. base modifiers, intercalating agents, and base analogues)

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12
Q

Base Modifiers

A

Covalently modify nucleotide structure (C to U, A to H)

Ex. Nitrogenous mustards

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13
Q

Intercalating Agents

A

Contain flat, planar structure which form double helix that distorts helical structure of DNA to result in frameshifts

Ex. Proflavin

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14
Q

Base Analogues

A

Become incorporated into daughter strand during replication

Ex. 5-bromouracil is a T analogue

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15
Q

Ionizing radiation can cause ____

A

damage to DNA backbone and double stranded breaks

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16
Q

Non-ionizing radiation such as UV light exposure can result in the formation of ____, which then do not base pair properly

A

thymine dimers

17
Q

Ames Test

A

For determining if a substance is a mutagen, monitors the rate of a second mutation restoring the function of histidine synthesis to S. typhimurium, uses rat liver extract to induce mutations

18
Q

____ can repair thymine dimers using visible light energy

A

Photolyse

19
Q

Alkyltransferase

A

Repairs alkylated bases (methylated), transfers methyl/ethyl group to itself to inactivate

20
Q

Base Excision Repair (BER)

A

Removes damaged bases, abnormal bases

21
Q

Nucleotide Excision Repair (NER)

A

Removes damaged DNA segments, can fix T dimers, modified or missing bases, and is found in all eukaryotes and prokaryotes

22
Q

NER in E. coli requires 4 key proteins: ____, which are involved in UV light repair and recognize and remove short DNA strands

A

UvrA, UvrB, UvrC, and UvrD

23
Q

Homologous Recombination

A

Involves crossing over between identical/homologous chromosomal regions, occurs during meiosis I, involves pairing of homologs, breaking at analogous locations, and exchange of corresponding segments

24
Q

Sister chromatid exchange (SCE) produces new ____

A

allelic combinations

25
Q

Holliday Recombination Model

A

When two ds DNA strands interact, can result in either non-recombinant or recombinant chromosomes gaining a heteroduplex region

26
Q

Double Strand Break Model

A

Similar to Holliday model, however it proposes a double strand break on one of the chromatids, requiring DNA gap repair synthesis

27
Q

E. coli contains many proteins playing a role in recombination, such as:

A
  • RecBCD
  • SSBPs
  • RecA
  • RuvABC
  • RecG
28
Q

Two mechanisms accounting for gene conversion:

A
  1. DNA mismatch repair
  2. DNA gap repair synthesis