2.6 Mutations Flashcards Preview

COB Genetics > 2.6 Mutations > Flashcards

Flashcards in 2.6 Mutations Deck (81)
Loading flashcards...
1
Q

What is ALS caused by?

A

can come from a couple mutations. Caused by fragile sites that are prone to breaks. Anticipation. Expands and when it gets too big, doesn’t fold correctly and forms placks.

2
Q

What does the Tinman gene (NKX2.5) do?

A

Regulate heart development.

3
Q

What are the modiators of early heart development?

A

Transcription factors.

4
Q

Individual nucleotide changes in transcription factors can lead to what?

A

Specific outcomes

5
Q

When do somatic mutations occur?

A

Something that happens post fertilization.

6
Q

Can somatic mutations be passed on?

A

No

7
Q

Where do somatic mutation arise in?

A

Tissues other than those that produce gametes

8
Q

When do germ-line mutations occur?

A

Happens during meiosis and are in the germ line.

9
Q

Where do germ-line mutations arise?

A

In tissues that produce gametes

10
Q

Can germ-line mutations be passed on?

A

Yes

11
Q

Are gene mutations always harmful?*

A

The majority are harmful but not always.

12
Q

What is a De novo mutation?

A

Basically a new mutation.

13
Q

What is a good example of a De novo mutation?

A

Cancer

14
Q

Can De novo mutations be inherited?

A

No

15
Q

What are the two categories to base substitutions?

A

Transition and transversion

16
Q

What are the two categories for insertions and deletions?

A

Frameshift mutations, and in-frame insertions/deletions

17
Q

What are expanding nucleotide repeats?

A

increase in the number of copies of a set of nucleotides

18
Q

what does a base substitution alter?

A

a single codon

19
Q

What does an insertion or a deletion alter?

A

many codons

20
Q

What is a transition mutation?

A

Substitute a purine for a purine, same with a pyrimidine

21
Q

What is a transversion mutation?

A

Substitute a purine for a pyrimidine and vice versa.

22
Q

What is fragile X?

A

Region of number of repeats that is prone to mismatch repair and it can expand into generations (anticipation) once reaches threshold it’s a nonfunctional protein. Cognitive problems in bois

23
Q

What is one disease that results from expanding nucleotide repeats?

A

ALS

24
Q

What are 7 phenotypic effects of mutations?

A

Loss of function mutation. Neutral mutation. silent mutation. Missense mutation. Nonsense mutation. Forward mutation. Reverse mutation.

25
Q

What is loss of function mutation?

A

Causes complete or partial absence of a normal protein function. Recessive.

26
Q

What is a neutral mutation?

A

Alters AA seq but doesnt change the function of the protein

27
Q

What is a silent mutation?

A

Changes the codon seq but not the AA

28
Q

What is a missense mutation?

A

Base substit that results in a dif AA

29
Q

What is a nonsense mutation?

A

Codon turns into a stop codon

30
Q

What is a forward mutation?

A

Alters the wild-type phenotype

31
Q

What is a reverse mutation?

A

Changes the mutant phenotype back into the wildtype.

32
Q

Mutations affect coding sequence, but where can they also affect?

A

Promoter, non coding sequences, Splice sites

33
Q

Which two mutations change the codon seq but not the AA?

A

Silent and Synonymous

34
Q

What is the mutation for Charge syndrome?

A

C replaced by T. Resulting in a stop codon.. Nonsense mutation.

35
Q

What are the two types of gene mutations?

A

Gain of function and suppressor mutation.

36
Q

What are the two subcatagories of suppressor mutations?

A

Intragenic and intergenic

37
Q

What is a gain of function mutation?

A

Produces a new trait.

38
Q

What is a supressor mutation?

A

Hides or suppresses the effect of another mutation

39
Q

What does intragenic mean?

A

Occurs in the same gene as that containing the mutation being suppressed

40
Q

What does intergenic mean?

A

Occurs in gene other than the one bearing the original mutation

41
Q

What is a lethal mutation?

A

Causes premature death

42
Q

What is a frameshift mutation?

A

Insertion or deletion that alters the reading frame of a gene

43
Q

What is an in-frame deletion or insertion?

A

Deletion or insertion of a multiple of 4 nucleotides that doesn’t alter the reading frame

44
Q

What are 4 factors that affect mutation rates?

A

Freq with which a change takes place in DNA. Probability that when a change takes place, that change will be repaired. Environmental factors. Genetic background.

45
Q

What is adaptive mutation good for?

A

Genetic variation critical for evolutionary change.

46
Q

What 4 things are mutations potentially caused by?

A

Replication errors, chemical changes, chemically induced mutations, radiation

47
Q

What are 4 examples of replication errors?

A

Tautomeric shifts, mispairing due to other structures, incorportation errors and replication errors, causes of deletion and insertions.

48
Q

What are two causes of deletion and insertions?

A

strand slippage and unequal crossing over

49
Q

What is non-watson and crick base pairing?

A

Mispairing due to altered protanation.

50
Q

What does strand slippage result in?

A

Loss or gain of 1 nucleotide

51
Q

What are InDels?

A

Unequal crossing over produces small inserts and deletions.

52
Q

What is depurination?

A

Loss of a purine (A or G)

53
Q

What is deamination?

A

Loss of an amino group (N)

54
Q

What are 7 chemically induced mutations?

A

Mutagen, base analogues, Alkylating agents, Deamination, hydroxylamine, Oxidative reaction, intercalating agents.

55
Q

What is a base analogue?

A

Chemical structure similar to normal bases.

56
Q

What are two examples of base analogues?

A

5-bromouracil is analogue of T. Sometimes pairs with G. 2-Aminopurine pairs with T but may mispair with C

57
Q

What are alkyating agents? What is an ex of them?

A

Donate alkyl group (methyl and ethyl groups). Mustard gas

58
Q

What is deamination?

A

Nitrous acid

59
Q

What does hydroxylamine do?

A

Add hydroxyl group

60
Q

What are oxidative reactions? what is an ex?

A

Oxidative free radicals that convert G into something else that makes it mispair with A. Hydrogen peroxide

61
Q

What do intercalating agents do?

A

Insert themselves between adjacent bases in DNA, distorting helix structure.

62
Q

What are two forms of radiation?

A

Ionizing radiation and UV light

63
Q

What does ionizing radiation do?

A

Dislodges e- in tissue causing free radicals which damage DNA

64
Q

What does UV light do?

A

Induces pyrimidine dimers, that block replication

65
Q

What is the SOS system in bacteria?

A

allows bac cells to bypass the replication block with a mutation prone pathway

66
Q

What is the AMES test used for?*

A

To detect if something is mutagenic.

67
Q

How does the AMES test work?

A

Bac strain cant synthesize histidine. If something is mutagenic, itll grow on the plate with the bac strain.

68
Q

What are 4 pathways to repair changes in DNA?

A

Mismatch repair, direct repair, BER, NER

69
Q

Many incorrectly inserted nucleotides that escape proof reading are corrected by what pathway?

A

mismatch repair

70
Q

What is BER?

A

Repair mechanisms used to repair a nucleotide base.

71
Q

What is NER?

A

Repair mechanisms used to repair a chunk of nucleotides.

72
Q

What are two ways to repair ds breaks?

A

HR and nonhomologous end joining.

73
Q

Which is more accurate? HR or NHEJ?

A

HR

74
Q

What are translesion DNA polymerases used for?

A

Allow polys to skip over distortion but often leads to mutations

75
Q

What does the direct repair system repair?

A

pyrimidine dimers

76
Q

What does mismatch repair system repair?

A

Replication errors, mispaired bases and strand slippage.

77
Q

What happens in bloom syndrome?

A

Mutations in the gene encoding DNA helicase RecQ, resulting in flaws in sister chromatid exchange.

78
Q

What is Xeroderma Pigmentosum?

A

Abnormal skin pigmentation and acute sensitivity to sunlight. Have defective NER. Increased risk of skin cancer.

79
Q

What is cockayne syndrome and trichothiodystrophy

A

Neuro problems, mutations in some of the same genes caused by XP. No increased risk of cancer however.

80
Q

What is hereditary nonpolyposis colon cancer?

A

Responsible for 15% of colon cancers. Mutations in proteins that carry out mismatch repair process.

81
Q

What sites are good for predicting if deleterious mutations are significant?

A

Mutation taster, polyphen-2, and Database of genomic variants