DNA Repair & How Do Mutations Occur (Exam IV) Flashcards
1
Q
Cellular synthesis of new daughter strands of DNA from a parental strand during the s phase of the cell cycle needed for cell division
A
DNA replication
2
Q
Change in DNA sequence form a parental strand to a daughter strand
A
DNA mutation
3
Q
Result in altered gene expression, splicing or altered proteins generated from the mutated DNA sequence
A
Functional DNA mutations
4
Q
Division of the nucleus of eukaryotic cell, involving condensation of the DNA into visible chromosome & separation of the duplicated chromosome to form two identical sets
A
Mitosis
5
Q
Special type of cell division that occurs in sexual reproduction & involves two successive nuclear divisions with only one round of DNA replication, thereby producing haploid cells from a diploid cell
A
Meiosis
6
Q
Changes in the nucleotide sequence of a chromosomes that cause disease
A
Gene mutation responsible for disorders
7
Q
List the single base pair substitutions that may or may not result in disorders (5):
A
Deletion
Insertion
Substitution
Silent
Missense
8
Q
An identifiable segment of DNA sequence with a known physical location on a chromosomes & enough variation between individuals
A
Genetic marker
9
Q
The inheritance & co-inheritance of alleles of a given gene in genetic markers can be:
A
Traced
10
Q
Can help link an inherited disease with the responsible genes
A
Genetic markers
11
Q
DNA segments close to eachother on a chromosome tend to be:
A
Inherited together
12
Q
Used to track the inheritance of a nearby gene that has not yet been identified but whose approximate location is known
A
Genetic markers
13
Q
Genetic markers are used in:
A
Linkage analysis
14
Q
Variation between individuals in a population at specific nucleotides in their DNA sequence
A
Single nucleotide polymorphisms (SNPs)
15
Q
DNA sequence variants of a gene
A
Alleles
16
Q
Mechanism by which delaminated and depurinated nucleotides are repaired
A
Base excision repaur
17
Q
Mechanism by which pyrimidine dimers are repaired
A
Nucleotide excision repair
18
Q
Formed during homologous recombination which allows DNA strands to switch partners between two DNA double helices
A
Holiday junction
19
Q
DNA is under constant pressure to ____ in its DNA sequence
A
Acquire changes
20
Q
Most changes in DNA are repaired before they become
A
A stable part of DNA passed onto the daughter cells
21
Q
When mutations occur in somatic tissues:
A
They CANNOT be inherited
22
Q
Although mutations in somatic tissues CANNOT be inherited, they CAN:
A
Give rise to diseases such as cancer
23
Q
When mutations arise in the DNA of gametes:
A
They will be passed on to the offspring
24
Q
List the chromosome disorders that can cause genetic disease (5):
A
1- rearrangements
2- translocations
3- deletions
4- insertions
5- duplications
25
Single gene disorders can be (3):
Dominant
Recessive
Codominant
26
A ______ can give rise to disease
Single base pair change
27
Involve large chunks of DNA that get moved around
Chromosome disorders
28
Genetic diseases caused by multigenic or gene-environment interactions that can occur & contribute to the formation of a complex trait
Multifactorial or Complex disorders
29
Disorders that involve the X & Y chromosomes
Sex-linked
30
Mechanisms that cause mutations in the mitochondrial DNA & affect the genes they encode resulting in genetic disease
Mitochondrial disorders
31
Somatic mutations are ____ while germline mutations are ____
Non-inheritable
Inheritable
32
A mutation caused by cigarette smoking resulting in lung cancer would be categorized as:
Somatic mutation
33
A mutation in the p53 gene that typically would cause a form of cancer would be categorized as:
Somatic mutation
34
A mutation that affects the sperm or egg:
Germline mutation
35
Mutations that can be passed on to your children dependent upon the degree of the mutation
Germline mutation
36
Mutations that arise naturally during DNA replication (mitosis) or during meiosis
Spontaneous mutation
37
Mutations caused by exposure to environmental insults
Induced mutations
38
Environmental insults that cause can induced mutations include:
Radiation
Chemicals
39
A mutation in which the DNA sequence is altered but results in no change of amino acid
Silent mutation
40
A mutation that results in a single amino acid change
Missense mutation
41
A mutation resulting in a codon being products ultimately stopping translation & producing a truncated protein
Nonsense mutation
42
Nonsense mutations ultimately result in:
Truncated proteins
43
Mutations that disrupt the reading frame insertion or deletion of a base
Frameshift mutation
44
A mutation resulting in a glycine getting substituted for a valine would be a:
Missense mutation
45
The LRP5 mutation resulting in osteoporosis pseudoglioma syndrome producing truncated proteins is an example of:
Nonsense mutation
46
A purine getting exchanged for another purine or pyrimidine getting replaced by another pyrimidine is considered:
Transition mutation
47
A purine getting substituted for a pyrimidine (vice versa)
Transversion mutation
48
A type of mutation resulting in extra amino acids
Insertion
49
A type of mutation resulting in missing amino acids
Deletion
50
Maybe you have a single nucleotide deletion or insertion & because the mRNA reads every three nucleotides instead of it reading 1, 2, 3 its now reading 2, 3, 4 resulting in an altered protein- this is an example of:
Frameshift mutation
51
A Frameshift mutation typically results in the:
wrong amino acid being placed
52
Cystic fibrosis is due to a _____ mutation
3 base deletion of deltaF509 (phenylalanine)
53
List the types of mutations that don’t necessarily affect the protein being made but may affect the amount of or expression of the protein (4):
1- promotor/enhancers (nuclear receptors)
2- splice site
3- expanded repeat
4- transposons
54
Promotors & enhancers are
Nuclear receptors
55
Important for regulating the binding of a nuclear receptor to the DNA to tell that gene to be expressed or not expressed
Promotor
56
Mutating an important enhancer will:
Change the level of gene expression (amount of protein that gets made)
57
A class of sequencing elements found in DNA that are associated with the level of transcription & can be great distances from the start site of transcription
Enhancers
58
A mutation affecting the way the mRNA is spliced ultimately resulting in a protein with incorrect information in it
Splice site mutations
59
Where you would typically have a small repeat element of amino acids in DNA that gets exacerbated into a huge repeat element
Expanded repeat mutation
60
Huntington’s disease is caused by a ______ mutation
Expanded repeat
61
Mobile genetic elements that jump around in the genome & dependent upon where they are inserted can cause changes in gene expression
Transposons
62
Name the type of mutation
Silent
63
Name the type of mutation
Missense
64
Mutations can be designed by (nomenclature) (5):
1- amino acid change
2- position in genomic DNA
3- position in mRNA
4- position in cDNA
5- changes in the protein
65
Type of system is used in regards to nomenclature of mutations
Coordinate system
66
The mutation A1215T would mean:
Alanine at the position ____ in the protein is changed to a ____
1215; threonine
67
Single base pair differences at a specific position in the genome
SNPs
68
SNPs occurring within a gene can give rise to an:
Allele
69
How many SNPs are in the genome
Millions
70
We use SNPs to help identify where ______ might be located
Allele or trait causing mutations
71
Why do cells in our body need DNA repair
To have a mechanism to maintain genetic stability
72
Maintaining the genetic stability that an organism needs for survival requires not only an extremely accurate mechanism for ___________ but also mechanisms for repairing ___________ that occur continually in DNA
DNA replication
Accidental lesions
73
Most spontaneous changes in DNA are:
Temporary
74
Most spontaneous changes in DNA are temporary because:
They are immediately corrected through DNA repair mechanisms
75
The importance of DNA repair is evident from the large investment that cells make in:
DNA enzymes
76
Following the inactivation of a DNA repair gene, there is an:
Increased rate of mutaiton
77
DNA of each human cell loses about ______ bases everyday
5000 purine bases
78
Purine bases in DNA are lost daily due to the process of:
Deoxyribose hydrolyzation of N-glycosyl linkages
79
The spontaneous reaction of Deoxyribose hydrolyzation of N-glycosyl linkages
Depurination
80
A spontaneous deamination of cytosine in uracil in DNA occurs at rate of about _____ per cell per day
100 bases
81
DNA bases are also occasionally damaged by an encounter with:
Reactive metabolites
82
Ultraviolet radiation from the sun can produce a covalent linkage between two adjacent pyrimidine bases in DNA to form:
Thymine dimers
83
What type of linkage is produced & what bases are affected in DNA when thymine dimers are formed due to UV
Covalent linkages; pyrimidines
84
Hydrolytic attack includes:
Deamination & depurination
85
The most frequent spontaneous reactions
Hydrolytic attack
86
Oxidative damage to the DNA occurs due to generation of:
Reactive oxygen species
87
Hydrolytic attacks cleave off a base so you now have the deoxyribose base in the chain but:
No base associated with it
88
About 3% of the C nucleotides in vertebrate DNAs are _____ to help in controlling gene expression
Methylated
89
When 5-methyl cysteine nucleotides are accidentally deaminated they form the natural nucleotide:
Thymine
90
When the 5-methyl cytosine nucleotides are accidentally deaminated they form the natural nucleotide thymine however this T will be paired with _____ on the opposite strand, forming a _____
Guanine; mismatched base
91
About 1/3 of inherited human disorders are:
Single base mutations
92
The spontaneous deamination products of A & G are recognized as unnatural when they occur in DNA and thus are:
Readily recognized and repaired
93
Unnatural based are recognized and removed by a specific:
DNA glycosylase
94
The process of unnatural bases being removed by specific DNA glycosylase:
Base excision repair
95
If we have a hydrolytic attack of:
Adenine —->
Guanine —->
Cytosine —->
Thymine —->
Hypoxanthine
Xanthine
Uracil
Thymine= no deamination because there is no amino group to remove
96
Cytosine to uracil in DNA that is estimated to occur at a rate of 100 bases per genome per day
Deamination
97
The loss of 5000 A or G bases per day in each daughter cell due to thermal disruption of the N-glycosyl linkages to deoxyribose
Depurination
98
Thymine dimers are permutagenic lesions that alter the structure of DNA and consquently inhibit ____ & arrest _____
Polymerases
Replication
99
Dimers may be repaired by ____ or ____
Photoreactivation or nucleotide excision repair
100
Unrepaired dimers are:
Mutagenic
101
How do chemical modifications of nucleotides produce mutations in the case of deamination
DNA substitution (point mutation)
102
How do chemical modifications of nucleotides produce mutations in the case of depurinations
DNA deletions
103
In both DNA deamination and depurinations one strand:
Remains unchanged
104
Process that involves a specific nuclease that Carie’s out a regions of the strand that has the thymine dimer and then removes the damaged DNA & polymerase & ligase come in to heal it by synthesizing the short stretch that has been removed
Nucleotide excision repair
105
Single base pair changes often get repaired by _____ that involves a set of enzymes that are involved in removing the nick and replacing it using the other strand as a template to put back the nucleotide that was removed
Base excision repair
106
A location in DNA that has neither a purine nor pyrimidine base
AP site (apurinic/apyrmidinic site)
107
Double stranded breaks can efficiently be repaired by:
1. Non-homologous end joining
2. Homologous recombination
108
Non-homologous end joining is considered:
Quick & dirty
109
In the non-homologous end joining process- you have a nick in one strand and a nick in the other strand and what happens the nucleotides will be removed to create ______ so there is not extra material there & they can be rejoined
Blunt ends
110
When a few nucleotides get removed from the sequence through the quick & dirty repair process these are referred to as:
Scars
111
Homologous recombination only occurs in phases:
S & G2
112
When the damage of the double stranded break is repaired using information from the sister pair of the chromosomes from that gene
Homologous recombination
113
Both non-homologous end joining & homologous recombination result in the delay of progression from:
G1 to S phase & S to M phase
114
If each member of a chromosome pair contains the same allele
Homozygous
115
If each member of a chromosome pair carries a different allele
Heterozygous
116
Generally speaking _____ expresses the most sever phenotype
Homozygous dominant
117
But the case of ____ genes you only observe the phenotype in the homozygous recessive state
Recessive
118
The phenotype of a _____ gene will be observed in both the homozygous and heterozygous state
Dominant
119
Fancy way of saying you inherit one maternal & one paternal copy of a gene
Principle of segregation
120
Sexually reproducing organisms possess genes that occur in pairs and that only one ember of this pair is transmitted to the offspring
Principle of segregation
121
Gene at different loci are transmitted independently
Principle of independent assortment
122
Just because you inherit a copy of gene A doesn’t mean you are always going to inherit copy A of another gene
Principle of independent assortment
123
Mechanism to:
1- accurately repair double strand DNA breaks
2- exchange bits of genetic information
3- assures accurate chromosome segregation during meiosis
Homologous recombination
124
Homologous recombination has manny common features found in all cells & its guided by:
DNA base-pairing
125
In homologous recombination, inadvertent joining of two segments from different chromosomes that result in chromosomal translocations often result in:
Disease
126
Homologous recombination repairs double-stranded breaks:
Accurately
127
In the process of homologous recombination there is an exonuclease that degrades the ____ ends as DNA synthesis occurs
5’
128
In homologous recombination- as the exonuclease is degrading the 5’ ends as DNA synthesis occurs, there is also a migration of one strand onto the sister chromatid of the pair of chromosomes and that then becomes the:
Template
129
Hallmark of homologous recombination
Holliday junction
130
Kind of a branching point where you see one strand invading the other strand & using the other strand as a template for completing DNA synthesis
Holliday junction
131
Cross-strand exchange during homologous recombination
Holliday junction
132
The process of two DNA strands switching partner between two double helices creates a:
Holliday junction
133
We commonly see homologous recombination action during the _____ process
Meiosis
134
Sort of an alternative path that can take place depending on where cleavage takes place in the process of homologous recombination
Holliday junction
135
During homologous recombination- depending on where the cleavage takes place will determine whether ______ takes place or not
Crossing over
136
During the process of homologous recombination- cleavage location that does not result in crossing over will form a _______ while cleavage that results in the chromosomes crossing over will form a _______
Heteroduplex
Cross-over complex
137
Homologous recombination will take place between any two areas dependent upon:
How far apart they are
138
Genetic unit that defines the frequency for with which crossing over takes place as a percentage
Centimorgan
139
1 centimorgan =
1 cross over in 100 meiosis
140
1 centimorgan in DNA corresponds to about:
One million basepairs
141
DNA is under constant pressure to:
Acquire changes in its DNA sequence
142
Various types of mutations occur in DNA, some of which will give rise to ______ of any given gene
Altered protein variants
