Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BMS > DNA Introduction, Structure, Replication, and Repair > Flashcards

DNA Introduction, Structure, Replication, and Repair Flashcards

1
Q

Macromolecule that stores and expresses genetic information

-DNA and RNA

A

Nucleic Acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In cellular organisms, genes are composed of DNA. Some viral genomes are composed of

A

RNA (HIV)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are four functions associated with DNA?

A
  1. ) Replication
  2. ) Transcription
  3. ) Repair
  4. ) Recombination
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Joins two parental DNA segments to form a hybrid molecule

A

Recombination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Nucleic acids are polymers of

A

Deoxyribonuleotides or ribonucleotides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the three components of a nucleotide?

A
  1. ) A base (Purine or pyrimidine)
  2. ) A pentose sugar
  3. ) A phosphate group
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Allows DNA recognition by proteins that control gene expression

A

Base methylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Salmonella typhimurium bacteria cause food poisoning and virulence is absolutely dependent upon

A

DNA Methylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Blocks expression of virulence genes and prevents disease development in mice

A

Inactivation of DNA Adenine Methylase (dam)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Consist of a base linked to a pentose sugar via an N-linked glycosidic bond, but no phosphate group

A

Nucleosides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Nucleosides are converted to nucleotides by the addition of 1, 2 or 3 phosphate groups to

A

Position C-5 on the sugar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What do we call the RNA nucleosides?

A

Adenosine, Guanosine, Cytidine, Uridine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Can be potent drugs in anti-viral and anti-cancer therapy

A

Nucleoside analogs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The pyrimidine analogs 3ʼ-azido-2ʼ-deoxythymidine (AZT; zidovudine) and dideoxycytidine (ddC;zalcitabine) are used to treat

A

HIV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Nucleoside analogs are incorporated into growing DNA strands during viral or cellular DNA replication to

A

Block further DNA synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Formed between the 3ʼ-hydroxyl group on the sugar of one nucleotide and the 5ʼ-phosphate group of the next nucleotide, releasing a pyrophosphate group

-Connects nucleotides to make nucleic acids

A

Phosphodiester bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Enzymes that cleave polynucleotide chains by hydrolyzing phosphodiester bonds

A

Nucleases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Remove nucleotides from either the 5’ or 3’ ends of polynucleotide chains, depending on the specificity

A

Exonucleases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Only cleave internal phosphodiester bonds

A

Endonucleases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

One type of endonucleases that cleave DNA in a sequence specific manner and that are particularly useful in molecular biology.

A

Restriction enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The double helix has how many base pairs per helical turn?

A

10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Proteins that regulate gene expression bind to the

A

Major groove

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Histone proteins found in chromatin bind to the

A

Minor groove

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Certain anti-cancer drugs, such as dactinomycin (actinomycin D) exert their cytotoxic effect by

A

Intercalating into the minor groove, thereby disrupting DNA and RNA synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
How many H bonds are between 1. ) A and T 2. ) G and C
1. ) 2 | 2. ) 3
26
Energetically favored and they facilitate DNA strand separation during replication, repair, recombination and transcription. -when a molecule has fewer helical turns than relaxed DNA
Negative Supercoils
27
Can force DNA into a negative supercoil
Histones
28
Transiently break one or both DNA strands, pass the strand(s) through the break, and rejoin them.
Topoisomerases
29
Cuts a single strand of the double helix and does not require ATP
Topoisomerase I
30
Cuts both strands of the double helix and requires ATP
Topoisomerase II
31
Bacterial topoisomerase II that can introduce negative supercoils into relaxed DNA in addition to removing negative and positive supercoils
DNA gyrase
32
Drugs that inhibit topoisomerases are used in -Lead to cell death
Chemotherapy and as antibiotics
33
In prokaryotes, DNA is associated with non-histone proteins that can condense DNA to form a
Nucleoid
34
The complex of DNA in the nucleus with associated proteins is called
Chromatin
35
Small basic proteins rich in Arg and Lys -5 types
Histones
36
In chromatin, DNA is wound around a histone octamer comprised of two molecules each of H2A, H2B, H3, and H4. This complex is called a
Nucleosome
37
During interphase, when the cell is not dividing, chromatin can be distinguished as -extended, active form of DNA
Euchromatin
38
Affect the regional compaction of chromatin and the regulation of gene expression
Histone modifications
39
As soon as eukaryotic DNA replication is completed, one unit of histone H1 binds the spacer DNA to promote the tight packing of nucleosomes. As a result, the chromatin winds into a helical tubular coil called the
Solenoid
40
DNA replication is semiconservative, meaning replicated DNA molecules contain
1 new strand and 1 parental strand
41
Molecular machine in prokaryotes that carries out DNA replication
Replisome
42
Binds near the replication fork and uses ATP to force the DNA strands apart.
DNA Helicase
43
Synthesizes a short primer (~10 nucleotides) in the 5ʼ to 3ʼ direction by copying the DNA template strand. -Allows for DNA polymerase to begin replication
Primase (RNA polymerase)
44
Continuously synthesized at the replication fork on the lagging strand -Provide a free 3'-hydroxyl that serves as an acceptro for the first deoxyribonucleotide
Primers
45
Synthesized continuously in the 5ʼ to 3ʼ direction toward the replication fork
Leading strand
46
Synthesized discontinuously in short 5ʼ to 3ʼ Okazaki fragments directed away from the fork.
Lagging strand
47
1. ) Which polymerase(s) does most of the DNA synthesis? | 2. ) Which proofread?
1. ) DNA Polymerase III | 2. ) DNA Polymerases I and III
48
Functions in replication (primer removal and gap synthesis) and repair. Has 3' to 5' and 5' to 3' exonuclease activity -Only polymerase with 5' to 3' exonuclease activity
DNA polymerase I
49
Covalently joins Okazaki fragments by catalyzing the ATP-dependent formation of a phosphodiester bond between the leading and lagging strands
DNA Ligase
50
Has many origins of replication and is linear
Eaukaryotic DNA replication
51
What are the three eukaryotic DNA polymerases?
Polymerase alpha, delta, and epsilon
52
Contains a primase activity and synthesizes hybrid RNA/DNA primers
alpha polymerase
53
Synthesizes the bulk of lagging strand DNA, and displaces the 5ʼ ends of primers from Okazaki fragments, which are degraded by “flap exonuclease” FEN1 and other nucleases.
Polδ
54
Synthesizes the bulk of leading strand DNA.
Polε
55
What performs DNA replication in mitochondria?
Polγ
56
Consist of short non-coding G-rich repetitive DNA sequences (TTAGGG) and associated proteins at the ends of linear chromosomes.
Telomeres
57
A ribonucleoprotein complex with reverse transcriptase activity (hTERT): it synthesizes DNA using its RNA subunit as the template. It adds short DNA repeats to the 3ʼ-ends of linear chromosomes to prevent the loss of coding sequences
Telomerase
58
Telomerase inhibitors can limit
Cancer cell proliferation
59
Cancer cells typically display
Indefinite cell division and uncontrollable telomerase
60
Stable changes in DNA sequence (substitutions, deletions, insertions) that can lead to a phenotypic change in the cell
Mutations
61
Agents that damage DNA
Mutagens
62
In prokaryotes, strand-specificity for mismatch repair (MMR) is provided by DNA
Methylation
63
An endonuclease cleaves the newly synthesized strand on either side of the mismatch. A helicase and an exonuclease remove DNA from the newly synthesized strand between the site of incision and the mismatch. DNA Pol III fills the gap, followed by DNA ligase
Mismatch repair
64
One of the biggest causes of cancer in humans -accounts for 90% of patients with Lynch syndrome
Defects in the MMR
65
Repairs spontaneously occuring DNA base modifications (e.g. base damage caused by deamination of cytosine into uracil, depurination, alkylation, oxidation etc).
Base Excision Repair
66
The damaged base is recognized by a base-specific DNA glycosylase that cuts the N-glycosidic bond between the damaged base and the sugar deoxyribose and the base is released upon action of a helicase
Base excision repair
67
Can remove an infinite number of lesions including photoproducts, chemical adducts and intrastrand DNA adducts. However, it is the only mechanism that can remove bulky DNA adducts.
Nucleotide excision repair (NER)
68
What type of NER is used if the damage is in a transcriptionally inactive region of DNA?
Global Genomic NER
69
What type of NER is utilized if the damage is in a transcriptionally active region of DNA?
Transcription-Coupled NER
70
A gene-specific repair process that is triggered when a helix distortion caused by DNA damage blocks progression of RNA polymerase II along the transcribed (template) strand of the DNA double helix.
Transcription-coupled NER
71
Used to remove pyrimidine dimers caused by UV light
NER
72
Commonly caused by oxidative damage and are usually associated with loss of a single nucleotide, and by damaged 5ʼ- and/or 3ʼ-termini at the site of the break.
Single-strand breaks (SSBs)
73
Can be induced by ionizing radiation (gamma- and X rays), oxidizing agents (e.g. bleomycin) or topoisomerase inhibitors used for chemotherapy (e.g. camptothecin), some plant and microbial products (e.g. aflatoxins in moldy peanuts) or mechanical stress
Double-strand breaks (DSBs)
74
Can severely compromise genome stability and can lead to loss of chromosome fragments during mitosis, or chromosomal translocations that can induce cancer due to joining of the wrong DNA ends.
Failure to repair DSBs
75
What are the two different repair pathways of DSBs?
1. ) Non-homologous end-joining (NHEJ) repair | 2. ) Homologous recombination
76
The major pathway to repair DSBs, because it does not require any sequence homology. It can thus occur throughout the cell cycle without needing alingment with a homologous chromosome
NHEJ repair
77
NHEJ is very -Leads to the accumulation of random genetic mutations
Error Prone
78
NHEJ can also lead to
Chromosomal translocations
79
Non-mutagenic because it involves alignment of highly homologous DNA molecules, so that the information on the homologous sequence can be used to repair the broken DNA.
Homologous recombination
80
Restricted to the S and G2 phases of the cell cycle, when a sister chromatid is present
Homologous recombination

BMS (62 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions