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BIOCHEM (1st yr Med) - Harper's > 35 - DNA Organization, Replication, Repair > Flashcards

35 - DNA Organization, Replication, Repair Flashcards

1
Q

What is the substance within a chromosome? - condenses during cell division to form chromosomes

A

chromatin

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2
Q

Chromatin is consisted of

A

1.) dsDNA
2.) histones (basic)
3.) nonhistone proteins (acidic)
4.) RNA - in small quantity

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3
Q

Spherical particles that are composed of DNA would around an octameric complex of histone proteins

A

nucleosome

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4
Q

Histone protein characteristics

A
  • basic
  • hydrophobic
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5
Q

Organizational unit of chromatin

A

Nucleosome

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6
Q

Nucleosome composition

A
  • octamer of histones
  • 150 bp of DNA wrapped twice around the proteins
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7
Q

Nucleosome size

A

10 nm

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8
Q

Types of Histones

A
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9
Q

Covalent modification of core histone

A
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10
Q

DNA packing sequence

A

DNA > nucleosome (10nm fibril) > chromatin (30nm fibril) > chromosome

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11
Q

DNA in transcriptionally active regions is sensitive to nuclease attack of what enzyme

A

DNAse 1

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12
Q

Parts of a chromosome

A

(1) Chromatid
(2) Centromere
(3) Telomere

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13
Q
  • Transcriptionally inactive chromatin
  • Densely staining
  • Chromatin is high in meC content

*Histones contain relatively lower levels of certain “activating” covalent modifications - high er levels of “repressing” histone PTMs

A

Heterochromatin

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14
Q

Two types of heterochromatin

A
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15
Q

Transcriptionally active chromatin - would stain less densely

A

Euchromatin

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16
Q

Chromatid are connected at a (1) in (2) region

A

(1) centromere
(2) A-T rich region

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17
Q

Essential for segregation during mitosis; anchors the mitotic spindle

A

Kinetochore

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18
Q

Short T-G rich repeats

A

Telomeres

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19
Q

Enzyme responsible for telomere synthesis and maintaining its length

A

Telomerase

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20
Q

Telomere shortening is associated with

A

cancer and aging

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21
Q

Nucleotide sequences in a gene

A
22
Q

Target for recombination studies

A

Introns

23
Q

In transcription, the introns are eliminated via

A

splicing

24
Q

(True/False)

Most of the part of the DNA are non protein coding

A

False

25
Q

DNA sequence class

A
  1. nonrepetitive DNA
  2. Unique-sequence DNA
  3. Repetitive-sequence DNA
26
Q

Repetitive sequences

A
27
Q

LINEs

A

long interspersed repeat sequences

28
Q

SINEs

A

Short interspersed repeat solution

29
Q

Microsatellite repeat sequences application

A
  • polymerase chain reaction
  • reverse transcripted PCR
30
Q

Portion of the gene copied by RNA polymerase

A

Transcription unit

31
Q

RNA processing

A
  1. removal of introns
  2. ligate extrons
  3. RNA splicing of mature mRNA that appears at the cytoplasm
32
Q

Enzyme that unwinds the DNA in both directions from the origin

A

DNA Helicase

33
Q

Two requirements for DNA replication

A

1.) DNA template
2.) Free 3’-OH group

34
Q

(1) RNA primers that bind to the DNA are produced by

(2) removes RNA primers by

A

(1) primase

(2) 5’-3’ exonuclease activity of DNA polymerase 1

35
Q

DNA replication enzymes

A
36
Q

Enzyme that covalently closes the DNA

A

Ligase

37
Q

5’ - 3’ strand that has continuous replication

A

Leading strand

38
Q

3’ to 5’ strand with discontinuous replication

A

Lagging strand

39
Q

DNA chain is covalently proposed, etc.

A

DNA ligase

40
Q

What is released when the new base forms a phosphodiester

A

Pyrophosphate

41
Q

3 Important properties

A
  • chain elongation
  • processivity
  • proofreading
42
Q

Dangerous radioactive chemicals

A

Genotoxin

43
Q

What is the smallest unit of genetic expression?

A. operon
B. locus
C. cistron
D. inducer

A

C. cistron

44
Q

What are the major products of RNA polymerase III?

A. snRNA
B. mRNA
C. rRNA
D. tRNA

A

D. tRNA

45
Q

What enzymes cut DNA at specific DNA sequences within the molecule?

A. Endonucleases
B. Ligases
C. Exonucleases
D. Polymerases

A

A. endonucleases

46
Q

In transcription

A. once the enhancer is located, DNA unwinds to expose transcriptions site

B. pyrophosphate is released following each cycle of polymerization

C. the nascent trinucleotide retains the 5- triphosphate of the initiating nucleotide

D. pyrophosphatases degrade the inorganic phosphate providing reversibility of the overall reaction

A

B

47
Q

To initiate transcription, the DNA-dependent RNA polymerase binds to

A. RNA transcript
B. promoter
C. beta subunits
D. methyl cap

A

B

48
Q

What comprises complementary DNA copies of the population of mRNAs in a tissue?

A. clones
B. sectors
C. library
D. chimera

A

A

49
Q

What enzymes catalyze bonds between DNA molecules, joining them?

A. endonucleases
B. ligases
C. exonucleases
D. polymerases

A

B

50
Q

Variations of DNA are called

A. mutations
B. polymorphisms
C. variants
D. recombinants

A

B

51
Q

What determines the peptide sequence?

A. orders of the codons in the mRNA
B. exons
C. anticodons in the rRNA
D. charged enzymes

A

C

52
Q

True of histone code EXCEPT

A. It is an important determinant of gene
activity.

B. Histones are subjected to specific post translational modifications.

C. Histone acetylation and deacetylation are best understood.

D. Posttranslational modifications histones are subjected to are irreversible. No. RATIONALIZATIO

A

D

BIOCHEM (1st yr Med) - Harper's (13 decks)

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