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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

A

primase

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
Q

Three DNA polymerases are involved in replication of nuclear DNA

A

DNA Pol a, d and e

26
Q

DNA polymerase involved in mitochondrial DNA replication

A

DNA polymerase gamma

27
Q
  • 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
A

DNA pol a/primase complex

(Eukaryotic: formation of the primer)

28
Q

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)

A

polymerase switching

29
Q
  • 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
A

Telomeres

30
Q

complete (nuclear) genetic information of a cell/organism

A

genome

31
Q

In_, genome is typically a single circular chromosome

In _, genome refers to one complete set of nuclear chromosomes

A

bacteria; eukaryotes

32
Q
  • a single nucleic acid molecule
  • much smaller than eukaryotic chromosomes
A

Bacterial and viral chromosomes

33
Q

only the centromeres are stained

A

C-banding

34
Q

due to differential staining along the length of each chromosome.

A

G-banding

35
Q
  • Satellite DNA
  • Found tens of thousands to millions of times
  • Each copy is relatively short (a few nucleotides to several hundred in length)
A

highly repetitive DNA

36
Q
  • 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
A

middle repetitive DNA

37
Q

multiple copy genes, mini-satellites, microsatellites

A

tandem repeats

38
Q

SINEs and LINEs

A

interspersed retrotransposons

39
Q

Three types of DNA sequences are required for chromosomal replication and segregation

A
  • Origins of replication (many)
  • Centromeres
  • Telomeres
40
Q

located between the centromeric and telomeric regions along the entire chromosome

A

genes (location)

41
Q

levels of eukaryotic chromatin compaction

A

naked DNA -> beads on a string-> solenoid-> loops-> radial loops->chromosome

42
Q
  • the substance chromosomes are made of
  • complex of chromosomal DNA and protein (and specific RNAs)
A

chromatin

43
Q

histones and nonhistone proteins

A

chromatin proteins

44
Q
  • 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
A

nonhistone proteins

45
Q
  • 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)
A

histones

46
Q

5 types of histones

A
  • H1: occurs in different variants
  • H2A H2B H3 H4= nucleosomal or core histones, each present in the same number of molecules
47
Q
  • 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
A

nucleosomes

48
Q

_ bp of DNA make 1.65 negative superhelical turns around the histone octamer

A

146

49
Q
  • 40 fold condensation
  • nucleosomes wrapped into rings and stacked
A

solenoid

50
Q
  • condensed and densely staining in interphase
  • genetically inactive
  • constitutive and factultative
A

heterochromatin

51
Q

constitutive heterochromatin

A

telomeres and centromeres

52
Q

facultative heterochromatin

A

can change to euchromatin

53
Q
  • decondensed and only weakly staining in interphase
  • genetically active
  • replicated first in S phase
A

euchromatin

54
Q
A

Genetics (17 decks)

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