Chapter 15: Mutations Flashcards

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1
Q

what is a mutation?

A

a change in the DNA sequence

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2
Q

what are the types of mutations?

A

point and frameshift

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3
Q

what is point mutation?

A

one nucleotide is changed to a different nucleotide
has the same number of nucleotides

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4
Q

what is frameshift mutation?

A

additional or deletion of at least one nucleotide
change the number of nucleotides

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5
Q

what are the types of point mutations?

A

silent, missense, nonsense

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6
Q

what are silent mutations?

A

the DNA sequence has been changed, but the new codon still codes for the same AA

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7
Q

a change in what base may not change the AA?

A

3rd base

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8
Q

what type of mutation?
one nucleotide has been changed to a different nucleotide
new codon codes for the same AA

A

silent

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9
Q

what type of mutation?
one nucleotide has been changed to a different nucleotide
new codon codes for the same AA

A

silent

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10
Q

what are missense mutations?

A

one nucleotide has been changed to a different nucleotide
new codon codes for a different AA

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11
Q

will silent mutations be functional?

A

yes- same function as before

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12
Q

will missense mutation be functional?

A

maybe, it would make a difference if it is in the active site and regulatory site
not make a huge difference when the AA is similar and it may work as a space holder

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13
Q

what is sickle cell anemia caused by?

A

point mutation in gene for hemoglobin=missense

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14
Q

what is nonsense mutation?

A

one nucleotide has been changed to a different nucleotide
new codon codes for a stop codon
new protein is shortened and missing some of its AA

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15
Q

will nonsense mutations be functional?

A

no, the protein is shortened

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16
Q

what type of mutation?
addition or deletion of at least one nucleotide
changes the number of nucleotides

A

frameshift

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17
Q

what are the types of frameshift mutations?

A

insertion and deletion

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18
Q

what is insertion frameshift?

A

additional of 1 or more nucleotides

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19
Q

what is deletion frameshift?

A

removal of one or more nucleotides

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20
Q

will frameshift mutations be functional?

A

no, many AA are changed because all codons are shifted over

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21
Q

where can mutations occur?

A

germ-line or somatic cells

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22
Q

what can mutations be?

A

harmful: cause changes in protein sequence or gene expression that leads to health problems
nuetral: no effect
beneficial: can have beneficial effect on health

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23
Q

mutations are the source of

A

new alleles

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24
Q

what are somatic cells?

A

body cell (not reproductive)

25
Q

what are germ-line cells?

A

reproductive cell that makes the sperm or eggs (gametes) testes or ovaries

26
Q

what happens if gametes have mutations?

A

all cells in embryo will have mutation
all cells in organism will have 1 copy of the mutation

27
Q

humans are diploid so 2N =
Gametes are haploid so 1N =

A

2 copies of each chromosome
1 copy of each chromosome

28
Q

how many gametes will have the mutation?

A

half

29
Q

what happens if somatic cells have mutations?

A

everytime the cell divides the daughter cells will inherit the mutation/ produce a patch of cells with the mutation

30
Q

what cells mutations will not be inherited and why?

A

somatic
none of the cells that produce the sperm or eggs have the mutation

31
Q

what causes mutations?

A

spontaneous and induced

32
Q

what are spontaneous mutations caused by?
types

A

caused by mistakes in cellular processes or metabolism

errors during DNA replication
toxic metabolic products
changes in nucleotide structures
transposons

33
Q

what is errors during DNA replication

A

proofreading does not remove all mismatched bases
DNA repair enzymes fail to remove all mistakes/ DNA damage

34
Q

what is toxic metabolic products?

A

metabolism produces relactive chemicals that change structures of bases in DNA

35
Q

when does toxic metabolic products occur?

A

after the DNA replication is done so the next time it is replicated there is a mistake

36
Q

what is changes in nucleotide structure?

A

bases can form isomers/ alternate forms = tautomers
can cause misprinting during DNA replication

37
Q

what is a tautomer?

A

alternate form of base

38
Q

each base can change between what two forms?

A

standard form and tautomer ( alternative form)

39
Q

If the base is in the ___ form during DNA replication the ____ base can be inserted into the DNA = ____ mutation

A

alternate
wrong
spontaneous

40
Q

what are transposons?

A

jumping genes
1000 bases long
if a transposing inserts into a gene it will cause a mutation

41
Q

what type of mutation is transposons?

A

insertion frameshift
when the transposon goes into the coding region it will form a really long mRNA and will be nonfunctional

42
Q

what are induced mutations caused by?

A

environmental agents
- chemicals
- physical agents: uv light, x-rays

43
Q

what is adenine?

A

an abnormal base in DNA

44
Q

what is induced mutations?

A

chemicals change the structure of bases in DNA

45
Q

what does uv light produce?

A

thymine dimers

46
Q

what is a thymine dimer?

A

2 thymines on the same strand of DNA form covalent bond

47
Q

during DNA replication thymine dimer is recognized as
what is added/produced

A

1 abnormal base not 2 Ts
mismatched base may be added
a deletion may be produced

48
Q

what is the process of thymine dimers?

A

uv light causes thymine dimer
crosslinks 2 thymines on same strand of DNA
blocks DNA replication

49
Q

thymine dimers cause

A

mistakes during DNA replication

50
Q

what are the types of DNA repair systems?

A

mismatch repair
nucleotide excision repair (NER)

51
Q

what is mismatch repair?

A

removes mismatched bases that are present after DNA replication is completed

52
Q

what is nucleotide excision repair?

A

removes abnormal bases (u, hypoxanthine) and thymine dimers

53
Q

in nucleotide excision repair, the ___ and ___ proteins form a ___ and move along the DNA looking for ____ bases

A

UvrA and UrvB
complex
abnormal

54
Q

how does mismatch repair work in relation to nucleotide excision repair?

A

the same just with different proteins

55
Q

what are the steps for nucleotide excision repair?

A

1) the UrvA and UrvB proteins form a complex and move along the DNA looking for abnormal bases
2)the UrvA and UrvB bind to region of DNA surrounding the abnormal base=thymine dimer
3) UrvA is released
4) UrvC binds to UrvB and cuts out a region of DNA surrounding the abnormal base= thymine dimer
5) UrvD unwinds DNA and removes cut piece of DNA
6) DNA polymerase 1 fills in gap with DNA
7) DNA ligase connects pieces of DNA together

56
Q

what is xeroderma pigmentioa?
symptoms/ results

A

disease caused by defect in DNA repair enzymes that remove thymine dimers

patients blister or freckle when exposed to sunlight
develop precancerous lesions
skin cancer
can’t go out in sun even with sunscreen

57
Q

what is myostatin?

A

inhibits growth of muscle cells

58
Q

mutation that inactivates myostatin causes

A

overproduction of muscle cells

59
Q

what is the bully mutation and how is it occurring

A

myostatin
naturally