Brainscape's Knowledge GenomeTM

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


See full index

Abnormal Amnio > Biochem - DNA Replication > Flashcards

Biochem - DNA Replication Flashcards

1
Q

Central Dogma

A

DNA —> RNA –> Protein

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

Central dogma for all organisms except…

A

some viruses

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

Significance of DNA replication

A

transmit genetic info to offspring, be performed with high fidelity, defects –> genetic instability –> mutations and disorders

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

Semiconservative DNA replication

A

parental strands are permanently separated

each forms a duplex molecule with the new complementary daughter strand

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

AT, GC H bonds

A

2 H bonds for A-T

3 H bonds for G-C

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

Substrates for DNA polymerases?

A

Deoxyribonucleoside triphosphates (dNTPs)

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

What actually gets added to the growing DNA chain?

A

dNMPs - processive process

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

How a dNTP –> dNMP and adds to the DNA chain

A

Incoming dNTP forms bp with complementary NT on parental strand
phosphodiester bond is formed
Pyrophosphate is released (PPi)
generates large energy change –> drives DNA synthesis

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

Type of bond made between incoming NT to the DNA chain

A

phosphodiester bond made between 5’ phosphate of incoming dNTP and free 3’ OH of the end of the chain
Bond is a 3’-5’ phosphodiester bond

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

Hydrolysis of PPi

A

PPi –> 2Pi generates a large energy change

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

DNA replication occurs in …

A

S phase of cell cycle in eukaryotic cells

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

oriC

A

origin of replication in E. coli

contains short AT rich sequences

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

Primosome

A

Protein complex that initiates DNA synthesis
Initiate unwinding of the duplex DNA
stabilize the DNA template single strands
initiate the synthesis of the RNA primers required for DNA synthesis

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

Primosome proteins?

A 
DnaA
DnaC
DnaB (Helicase)
SSB
DnaG (DNA primase)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

DnaA

A

tetrameric DNA binding protein with specificity for oriC
Involved in directing other primosome proteins to the origin
ATP required for initial melting of AT region

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

DnaC

A

Helicase inhibitor that is required for loading DnaB onto the strand

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

DnaB

A

DNA helicase
further separates the duplex DNA
ATP is hydrolyzed

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

SSB

A

Single stranded DNA binding protein

Stabilized ssDNA

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

DnaG

A

DNA Primase

generates short RNA primers for DNA synthesis

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

Primosome binding process

A 
DnaA binds to the replication origin
DnaB binds to the DNA
DnaB opens the helix and binds DnaG to form primosome
RNA primer synthesis
DNA polymerase can start first DNA chain
21
Q

Semidiscontinuous manner

A

DNA has anti-parallel structure
DNA synthesis can only occur in 5–>3’ direction
Replication fork moves in 5–>3 for one strand but 3–>5 for the lagging strand

22
Q

Leading strand

A

Synthesized continuously in 5–>3’ direction

Moves in same direction as fork

23
Q

Lagging strand

A

Synthesized in opposite direction

Discontinuous DNA fragments must be joined together by DNA ligase

24
Q

Okazaki fragments

A

discontinuous DNA fragments on the lagging strand

25
Q

Replisome

A

elongation of DNA requires additional proteins

26
Q

Replisome proteins

A

DNA polymerase
DNA ligase - ATP hydrolysis
Topoisomerases
Sliding clamp

27
Q

Sliding clamp

A

Made up of 2 halves
Clamp loader places clamp on DNA in ATP dependent process
Clamp keeps DNA pol to be processive

28
Q

DNA ligase

A

seals nicks between DNA fragments
Seals in 3’–>5’ fashion
ATP hydryolysis
E. coli is NAD-dependent

29
Q

E. coli DNA pol I

A 
Monomeric
5-->3' elongation
3-->5' exonuclease proofreading
5-->3' exonuclease
Remove RNA primers
Replace RNA primers with DNA
Slow, low processivity
30
Q

E. coli DNA pol III

A 
5-->3' elongation
3-->5' exonuclease proofreading
 No 5-->3' exonuclease
Recognizes RNA primers
Fast, high processivity
Major replicative polymerase
31
Q

Termination of replication

A

replication forks meet in region with multiple copies of ter sequence
Proteins bind and trap/arrest the fork by inhibiting DnaB

32
Q

Why PPi –> 2Pi

A

If you keep taking out the product, then you can keep pushing the reaction to go forward

33
Q

Why is eukaryotic DNA replication more complicated?

A

Size and organization of euk DNA
Multiple origins of replication, many forks
Primer removal (5–>3’ exonuclease) is done by RNaseH

34
Q

ORC in eukaryotes

A

Origin recognition complex - 6 proteins
Analogous to DnaA
Phosphorylation of ORC allows binding of proteins like primosome
Onset of S phase - DNA pol alpha-primase binds to make it an active complex

35
Q

DNA pol alpha

A

Nuclear
Initiation, primase activity, synthesize 20nt
5–>3’ polymerase
No 3–>5’ exonuclease

36
Q

DNA pol beta

A

Nuclear
DNA repair
5–>3’ polymerase
3–>5’ exonuclease

37
Q

DNA pol delta

A

Nuclear
Elongation - chromosomal DNA replication
5–>3’ polymerase (highly processsive)
3–>5’ exonuclease

38
Q

DNA pol epsilon

A

Nuclear
Elongation - chromosomal DNA replication
5–>3’ polymerase (highly processive)
3–>5’ exonuclease

39
Q

DNA pol gamma

A

Mitochondrial
Replication of mitochondrial genome
5–>3’ polymerase
3–>5’ exonuclease

40
Q

Nucleosomes

A 
H1, H2A, H2B, H3, H4
Positively charged (ionic bond with DNA)
Core histones = 2A, 2B, 3, 4 + Linker H1
Duplicated during DNA synthesis
Synthesized mostly in S phase
41
Q

Telomere

A

non-coding NT sequences at ends of linear chromosomes
Maintain the structural integrity of eukaryotic chromosomes
Protozoa - GGGGTT
Euk - AGGGTT

42
Q

Telomere sequences

A

Protozoa - GGGGTT

Euk - AGGGTT

43
Q

Shelterin

A

Protein in telomeres that functions to protect ends from being recognized as DNA breaks

44
Q

Problem with telomeres?

A

RNA primer on the end of lagging strand at 5’ is shorter with each DNA replication
Removal of the primer leads to a shorter strand

45
Q

Telomerase

A

Ribonucleoprotein
Contains RNA molecule that serves as template for elongation of G rich strand of telomeric DNA
Has a protein with polymerase activity
Only found in - germ cells, early embryonic cells, cells that divide continuously

46
Q

Telomerase process

A

Telomerase extends the 3’ end of DNA
RNA primer is synthesized by primase at end of 3’ end
RNA primer serves as primer for DNA polymerase
Polymerase extends in 5’–>3’
RNA primer is removed

47
Q

Hutchinson-Guilford Progeria

A

Disease of very premature aging
Due to mutations in nuclear proteins - lamins
Dramatically shortened telomeres at early age

48
Q

Why do SSB proteins exist?

A

Don’t let ssDNA base pair, get degraded, form a duplex

Cell thinks ssDNA is a virus

Abnormal Amnio (5 decks)

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