chapter 11 Flashcards
(79 cards)
1
Q
germ line mutations
A
mutations that occur in the germ line (sperm and egg )
2
Q
somatic mutations
A
mutations in cells that are not the germ cells
3
Q
what type of mutations can be passed from one generation to the next
A
germ line
4
Q
point mutations
A
- localized
- occur at specific location in genome
- varied consequences
5
Q
what are the two types of point mutations
A
coding sequence
regulatory
6
Q
what are the categories of coding sequence mutations
A
- synonymous
- missense
- nonsense
- frameshift
7
Q
what are the categories of regulatory mutations
A
- promoter
- polyadenylation
- splice site
- DNA replication
8
Q
synonymous mutation consequences
A
no amino acid sequence change, end up with same amino acid
9
Q
missense mutation consequences
A
changes the amino acid (one)
10
Q
nonsense mutation consequences
A
creates stop codon and ends translation
11
Q
frameshift mutation consequences
A
creates wrong sequence of amino acids and premature stop codons may exist
- done so by inserting or deleting one or more base pairs
12
Q
promoter mutation consequences
A
changes timing or amount of transcription
13
Q
polyadenylation mutation consequences
A
alters sequence of mRNA and can block proper processing of mRNA
14
Q
splice site mutation consequences
A
improperly retains an intron or excludes an exon
15
Q
DNA replication mutation consequences
A
increases number of short repeats of DNA
16
Q
base pair substitution mutations
A
replacing one nucleotide base pair by another
17
Q
transition mutations
A
- one purine replaces another
OR - one pyrimidine replaces another
18
Q
transversion mutations
A
pyrimidine replaced by purine (and vice versa)
19
Q
what are the three types of base- pair substitution methods
A
- synonymous
- missense
- nonsense
20
Q
what are cryptic splice sites
A
base pair substitution mutations that produce new splice sites that replace or compete with original splice sites
21
Q
forward mutation
A
converts wild type to mutant
22
Q
reverse/reversion mutation
A
convert mutant allele back to wild type
23
Q
true reversion
A
wild type DNA restored by second mutation that happens within same codon
24
Q
intragenic reversion
A
restores wild type through second mutation elsewhere in same genome
25
second site reversion
restore wild type through second mutation in a different gene that suppresses the mutant from first mutation
26
what is the rate of mismatches that occur
1x10^-9 per nucleotide per site per year
27
how do alternations in number of DNA repeats occur
through strand slippage
28
what is strand slippage
- DNA polymerase temporarily slips off
- hairpin structure formed with the repeats
- DNA polymerase comes back through and reads these repeats within the hairpin structure and adds more repeats
29
trinucleotide repeat expansion disorders
strand slippage mutations that cause hereditary diseases
30
what is non-Watson-and-Crick base pairing
when non-complementary base pairing occurs
31
incorporated error
- G with T OR C with A
- incorporation of the wrong nucleotide
32
replicated error
replication of error without repair converts it into a mutation
33
depurination
loss of purine from nucleotide by breaking covalent bond
34
what is formed after a depurination
apurinic site
35
what is usually added in place of the lost nucleotide during depurination
A
36
deamination
loss of an amino group from a nucleotide base
37
what are the four common systems for direct DNA repair
photoreactive repair
base excision repair
nucleotide excision repair
mismatch repair
38
photoreactive repair
photolyase uses energy from visible light to break bonds producing the photoproduct
39
what is the basis of base excision repair
- can cut out region that was incorrect and basically fill back in
- sending DNA polymerase over incorrect region again
40
what is the process of base excision repair
- glycosylases recognize and remove modified bases to create AP site
- AP endonuclease creates nick near AP site
- nick opens up covalent bond on backbone
- DNA polymerase comes back through and removes and replaces nucleotides on nicked strand
41
process of nucleotide excision repair
- enzymes recognize and bind to damaged region
- segment of nucleotides removed from damaged strand
- polymerase fills in the gap
- ligase seals backbone
42
what helps to make nicks
UVR C
43
what is the job of UVR D
binds to damaged site and remove damaged strand
44
how does mismatch repair work
repair enzymes distinguish between correct (original) nucleotide and mismatched (new) nucleotide using presence of methylation strand
45
job of MutH
find methyl group of conserved region to identify parent strand and correct nucleotide
46
job of MutL
brings MutS and MutL together so that you have stabilized segregated region
47
what is ATM important for
used through signal transduction pathway to activate transcription of p53
48
why is p53 important
regulation of the cell cycle
49
how does p53 work
pauses or stall a cell in transition phase
50
what are the outcomes of p53
- pause cycle at transition and allows time for repair
- paused cycle at transition for too long and causes cell death
51
in healthy cells, should p53 be high or low
low
52
what is used as backup when a lot of damaged has occurred (happens in E.coli a lot)
translesion DNA synthesis
53
process of SOS repair in E.coli
- pol II stalls at damaged DNA
- RecA protein coats template strand ahead of lesion
- DNA-RECA-SSB complex formed
- RecA activates transcription
- Pol V displaces pol III and then synthesizes new DNA
54
what are the two mechanisms to carry out a double strand break repair
- nonhomologous end joining
- synthesis dependent strand annealing
55
double strand breaks
broken both strands of chromosomes and makes chromosome unstable
56
nonhomologous end joining process
1. x-ray damage produces double strand break
2. Ku80-Ku70-PKCS complex bonds DNA ends
3. ends are trimmed causing loss of nucleotides
4. DNA ligase links end back together
57
used for break that happens before replication and is error prone
nonhomologous end joining
58
used for break that happens after replication and doesn't cause errors
synthesis-dependent strand annealing
59
process of synthesis-dependent strand annealing
1. once chromatid undergoes double stranded break
2. nucleases digest portion of broken strands and Rad51 binds undamaged chromatid
3. Rad51 brings broken chromosome to analogous chromosome to form D loop where replication fork forms
4. new strand synthesis takes place using intact strands for templates
5. partial strand excision occurs, duplexes reform, and strands ligated
60
homologous recombination
exchange of genetic material between homologous DNA molecules
61
when does homologous recombination occur in bacteria
- conjugation
- double stranded break repair
62
when does homologous recombination occur in eukaryotes
- prophase 1 of meiosis
- initiated by controlled double strand DNA breaks
63
what is the Holliday model
spontaneously generated single stranded breaks in one chromatid led to invasion of non sister chromatid on homolog that result in crossover of some
64
are double stranded breaks that initiate recombination spontaneous
no, they are generated in a program manner by special enzyme
65
what helps to trim the cut strands in double strand break model of homologous recombination
Mrx and Exo1 associate with Spo11
66
what helps facilitate strand invasion and formation of D loop in double strand break model of homologous recombination
Rad51 and Dmc1
67
how is the heteroduplex formed and what is it
- DNA of different homologous
- double strand DNA
68
what are the two ways to resolve double holiday junctions
1. opposite sense resolution
2. same sense resolution
69
what are transposable genetic elements
- DNA sequences that can move within the genome by transposition
- vary in length, sequence, composition, and copy number
70
how does movement occur in transposable genetic elements
1. excision of element from original location and insertion in new location
2. duplication of element and insertion of copy in new location
71
what are the two features of all transposable elements
1. contain terminal inverted repeats on its end
2. inserted transposable element is bracketed by flanking direct repeats
72
class 2 of transposable elements
DNA transposons: transpose as DNA sequences and may be replicative or Non replicative
73
class 1of transposable elements
composed of DNA transpose but move through RNA intermediate
74
replicative transposition
- copy and paste of the transposon
- leave original copy where it is on genome and make copy
75
Non replicative transposition
- cute and paste
- excise DNA and move it elsewhere
76
which type of DNA transposition increases the amount of DNA
replicative because it is adding more
77
insertion sequences (ISs)
simple transposable elements containing inverted repeats surrounding gene
78
composite transposons
carry a transposase gene, two flanking IS elements
79
Non composite transposons
lack IS elements
