Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Gene Regulation and Expression > DNA Replication Machinery I > Flashcards

DNA Replication Machinery I Flashcards

1
Q

Where does replication take place in the cell cycle

A

S phase

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

Duration of replication

A

8 hours (DNA synthesised ~50bp/sec)

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

Replication machinery is comprised of

A

DNA Polymerase and additional proteins

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

How have cellular proteins responsible for initiation, elongation, and cell cycle control been identified

A
  • mutants defective in replication
  • molecular, biochemical, structural, cytological
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Systems used to identify cellular proteins

A
  • PRO E.Coli
  • Viruses SV40 and Adenovirus
  • EU Yeast, Xenopus, Human, Drosophilia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Semi-conservative DNA Replication

A

each molecule of DNA ends up with one conserved strand and one newly synthesised strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

DNA Polymerase 5’-3’ chain elongation

A
  • DNA Polymerase synthesises DNA
  • activity requires presence of all deoxyribonucleic triphosphates, Mg2+ ions, and 3’OH group paired to DNA template
  • adds unpolymerised complementary deoxyribonucleic acids to the 3’OH end of the new DNA chain
  • can only proceed in 5’ to 3’ direction
  • incoming deoxyribonucleoside triphosphate loses the terminal two phosphate groups
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Initiation site

A
  • ## origins of DNA replication
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Daughter cell synthesis

A
  • using both of the exposed parental single strands as templates
  • antiparallel structure of two strands duplex DNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the synthesis of the lagging strand

A
  • discontinuously
  • 5’-3’ direction
  • series of short fragments; Okazaki
  • back-stitching process
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

DNA synthesis is synthesised

A

semi-discontinuously

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

What enzyme joins the Okazaki fragments

A

DNA ligase

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

EU DNA and Chromatin

A
  • EU and PRO DNA differ in that eukaryotic DNA is synthesized as Chromatin
  • DNA is complexed with tightly bound proteins called histones
  • DNA is wound around a disk-like shape formed by an octamer of histones -> creates nucleosome
  • chromatin remodelling enzymes can alter number and distribution of nucleosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Nucleosome inhibition of replication machinery

A
  • inhibit access of the machinery to the origin of DNA replication
  • act as barriers to slow down the movement of DNA replication forks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Disruption of the chromatin structure

A
  • by movement of the replication fork as DNA strands separate
  • nucleosomes are reformed immediately following replication of DNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Role of chromatin remodelling proteins

A

stimulate DNA replication

17
Q

Describe the movement of replication forks

A

outwards from the origins of replication in opposite directions

18
Q

Describe origin of replication in prokaryotes

A
  • circular
  • have one replication origin
  • replication forks proceed outwards from origin in opposite directions until the entire genome is duplicated
19
Q

Replication origins in large eukaryotic genomes

A
  • multiple DNA replication origins
  • replication is thought to proceed until it encounters a replication fork moving the opposite direction or until it reaches the end of chromosomes
20
Q

Clusters of replication origins in eukaryotic genome

A

within clusters only one origin is activated when there are sufficient nutrients, but all origins are activated when the nutrient supply is deficient, in order to replicate the DNA as efficiently as possible

21
Q

When are dormant origins activated

A

only when a problem arises that leads to the stalling of two converging replication forks, such that the interlying DNA is in danger of not being replicated

22
Q

Essential elements of DNA replication origins

A
  • binding sites for initiator/origin recognition proteins
  • start site of replication
  • elements for unwinding/distortion of DNA
23
Q

Non-essential regulatory elements of DNA replication origins

A
  • binding sites for activators/chromatin remodelers
  • contribute to efficiency of replication
24
Q

PRO E.Coli DNA replication origin

A
  • well-defined at the nucleotide level
  • can support replication of any piece of DNA containing it
  • initiator protein DnaA binds and contains two sets of AT-rich repeats
25
Q

EU S. cerevisiae DNA replication origin

A
  • well-defined at nucelotide level
  • DNA containing these origins can be replicated in yeast cells without having to be incorporated into the yeast chromosomes
  • yeast origins are also AT-rich with separate sites for binding of an origin recognition complex (ORC) and for binding of the protein ABF1
26
Q

Function of ABF1 in DNA replication

A

increases efficiency of initiation via recruitment of replication/chromatin remodeling factors to the replication origin

27
Q

Target sequences for replication proteins in DNA

A

no target sequences in origin conserved between EU despite conservation of replication initiation proteins

Gene Regulation and Expression (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions