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Genetics > Chapter 11 & 12 > Flashcards

Chapter 11 & 12 Flashcards

1
Q

Both parental strands stay together after DNA replication

A

Conservative model

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2
Q

The double-stranded DNA contains one parental and one daughter strand following replication

A

Semiconservative model

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3
Q

Parental and daughter DNA are interspersed in both strands following replication

A

Dispersive model

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4
Q
  • Used isotope of nitrogen to change the weight of DNA N15 & N14
  • demonstrated that the semi-conservative model is the best description of replication.
A

The Meselson-Stahl experiment

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5
Q

the fundamental reaction by which DNA is synthesized

A

The addition of a deoxyribonucleotide to the 3’ end of a polynucleotide chain (the primer strand)

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6
Q

DNA polymerase catalyzes DNA synthesis and requires _____, ____, ___

A

a DNA template, a primer, and all four dNTPs

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7
Q

Chain elongation occurs in the _ direction by addition of one nucleotide at a time to the _ end

A

5’ to 3’; 3’

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8
Q

As the nucleotide is added, the two terminal phosphates are cleaved off, released as _

A

pyrophosphate

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9
Q

enzymes that catalyze synthesis of DNA polynucleotide chains
- depend on single-stranded template DNA
- can add free nucleotides only to the 3’-OH end of an existing polynucleotide (DNA or RNA)

A

DNA polymerases

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10
Q

complex enzyme with ten subunits (called the holoenzyme)

  • responsible for the 5’ to 3’ polymerization essential in vivo
  • Its 3’ to 5’ exonuclease activity allows proofreading
A

DNA polymerase III

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11
Q
  • removes the RNA primer
  • fills the resulting gaps with DNA
A

DNA polymerase I

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12
Q

involved in various aspects of repair of damaged DNA

A

DNA polymerases I, II, IV, V

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13
Q

binds to the origin of replication and is responsible for the initial steps in unwinding the helix

A

DnaA

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14
Q
  • binding further opens and destabilizes the helix
  • separates the two DNA strands by breaking the hydrogen bonds between them
  • generates positive supercoiling ahead of each replication fork
A

DnaB and DnaC /helicases

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15
Q
  • stabilize the open conformation
  • bind to the separated DNA strands to keep them apart
A

Single-stranded binding proteins (SSBPs)

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16
Q

travels ahead of the helicase and alleviates the supercoils

A

DNA gyrase

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17
Q
  • synthesized by DNA primase
  • 10 to 12 nucleotides
  • start/ prime DNA synthesis
  • later removed and replaced with DNA
A

RNA primers

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18
Q

the new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5’ to 3’ direction

A

leading strand

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19
Q

A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each with a RNA primer and synthesized in a 5’ to 3’ direction away from the replication fork.

A

lagging strand

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20
Q

DNA polymerases have 3’ to 5’ __ activity that allows proofreading

A

exonuclease

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21
Q

prevents the core enzyme from falling off the template

A

Beta subunit sliding clamp

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22
Q

keeps parental strands apart

A

single stranded binding proteins

23
Q

synthesizes RNA primer

24
Q

replication in eukaryotic cells (3 reasons why its more complex than in prokaryotic)

A
  • the chromosomes are linear
  • the DNA is associated with proteins
  • there is more DNA than prokaryotic cells
25
Three DNA polymerases are involved in replication of nuclear DNA
DNA Pol a, d and e
26
DNA polymerase involved in mitochondrial DNA replication
DNA polymerase gamma
27
- synthesizes a short RNA-DNA hybrid -- 10 RNA nucleotides followed by 20-30 DNA nucleotides - used by DNA pol d or e for the elongation of the leading (e) and lagging (d) strands
DNA pol a/primase complex (Eukaryotic: formation of the primer)
28
Pol a is replaced by Pol d for elongation of the lagging strand, and by Pol e for elongation of the leading strand (after the RNA-DNA hybrid is made)
polymerase switching
29
- Provide Structural Integrity at Chromosome Ends but Are Problematic to Replicate - consist of long stretches of short repeating sequences - have a 3' overhang that is 12-16 nucleotides long - typically consist of several guanine and thymine nucleotides
Telomeres
30
complete (nuclear) genetic information of a cell/organism
genome
31
In_, genome is typically a single circular chromosome In _, genome refers to one complete set of nuclear chromosomes
bacteria; eukaryotes
32
- a single nucleic acid molecule - much smaller than eukaryotic chromosomes
Bacterial and viral chromosomes
33
only the centromeres are stained
C-banding
34
due to differential staining along the length of each chromosome.
G-banding
35
- Satellite DNA - Found tens of thousands to millions of times - Each copy is relatively short (a few nucleotides to several hundred in length)
highly repetitive DNA
36
- tandem repeats and interspersed retrotransposons - Found a few hundred to a few thousand times - Includes genes for rRNA and histones, Origins of replication, and Transposable elements
middle repetitive DNA
37
multiple copy genes, mini-satellites, microsatellites
tandem repeats
38
SINEs and LINEs
interspersed retrotransposons
39
Three types of DNA sequences are required for chromosomal replication and segregation
- Origins of replication (many) - Centromeres - Telomeres
40
located between the centromeric and telomeric regions along the entire chromosome
genes (location)
41
levels of eukaryotic chromatin compaction
naked DNA -> beads on a string-> solenoid-> loops-> radial loops->chromosome
42
- the substance chromosomes are made of - complex of chromosomal DNA and protein (and specific RNAs)
chromatin
43
histones and nonhistone proteins
chromatin proteins
44
- Many proteins of different functions - present in chromatin - 5,000 - 10,000 encoded in the human genome - ex: DNA and RNA polymerases, DNA repair enzymes, transcription factors, kinetochore proteins, topoisomerases
nonhistone proteins
45
- function in the compaction of DNA in the nucleus - synthesized at same time as DNA (S-phase) - small and basic (high content of arginine and lysine)
histones
46
5 types of histones
- H1: occurs in different variants - H2A H2B H3 H4= nucleosomal or core histones, each present in the same number of molecules
47
- the repeating structural unit within eukaryotic chromatin - composed of double-stranded DNA wrapped around an octamer of histone proteins - Beads on a string; 5 fold condensation
nucleosomes
48
_ bp of DNA make 1.65 negative superhelical turns around the histone octamer
146
49
- 40 fold condensation - nucleosomes wrapped into rings and stacked
solenoid
50
- condensed and densely staining in interphase - genetically inactive - constitutive and factultative
heterochromatin
51
constitutive heterochromatin
telomeres and centromeres
52
facultative heterochromatin
can change to euchromatin
53
- decondensed and only weakly staining in interphase - genetically active - replicated first in S phase
euchromatin
54

Genetics (17 decks)

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