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Molecular Motors- Helicases

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Structural Basis for Biological Function (Molecular Motors) Quiz on Molecular Motors- Helicases, created by gina_evans0312 on 15/12/2013.
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Quiz by gina_evans0312, updated more than 1 year ago
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Created by gina_evans0312 almost 11 years ago
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Resource summary

Question 1

Question
DNA helicase unwinds DNA into ssDNA for what processes?
Answer
  • DNA repair
  • DNA replication
  • DNA recombination
  • DNA destruction

Question 2

Question
DNA helicase's process and translocate branched structures
Answer
  • True
  • False

Question 3

Question
Name (a) branched DNA structure(s)
Answer
  • Holliday junctions
  • D loops
  • Binary helix
  • T loops

Question 4

Question
RNA helicases cannot destabilize RNA secondary structures
Answer
  • True
  • False

Question 5

Question
RNA helicases help in which of the following processes A- Promote ribosome assembly B- RNA translocation C-RNA splicing D- RNA editing and transport E-RNA degredation
Answer
  • A, C & D
  • B, C & E
  • A only
  • E only
  • All of them

Question 6

Question
Some helicases can work on both RNA & DNA
Answer
  • True
  • False

Question 7

Question
Which of the following unwind RNA-DNA hybrids
Answer
  • RNA helicase, then DNA helicase
  • DNA helicase, then RNA helicase
  • RNA/DNA helicases

Question 8

Question
RNA/DNA helicases perform which of the following functions?
Answer
  • Transcription termination
  • Regulation of DNA replication initiation
  • RNA degredation

Question 9

Question
All helicases use energy from NTP hydrolysis to translocate along polynucleotides
Answer
  • True
  • False

Question 10

Question
Helicases are dependent on Fe2+
Answer
  • True
  • False

Question 11

Question
Helicases can take which of the following forms (commonly)
Answer
  • Hexamers
  • Monomers
  • Trimers
  • Dimers
  • Tetramers
  • Pentamers

Question 12

Question
Helicases can have an oligomeric structure
Answer
  • True
  • False

Question 13

Question
Helicases can be
Answer
  • Unidirectional
  • Bidirectional
  • Both
  • Bidirectional or unidirectional

Question 14

Question
What is the difference between translocases and helicases?
Answer
  • Translocases -transcribe and separate DNA strands Helicases- transcribed DNA strands only
  • Helicases-transcribe and separate DNA strands Translocases- transcribed DNA strands only

Question 15

Question
Give an example of a DNA/RNA unwinding helicase/translocase
Answer
  • PCRA
  • Type 1 restriction enzymes
  • Ruv B/Reg G
  • Mfd

Question 16

Question
Name a helicase/translocase that effects protein motion on DNA
Answer
  • PCRA
  • Type 1 Restriction Enzyme
  • Ruv B/ Reg G
  • Mfd

Question 17

Question
Name a necleoprotein complex remodelling helicase
Answer
  • Mfd
  • Ruv B/Reg G
  • PCRA
  • Type 1 Restriction Enzymes

Question 18

Question
Name a DNA/RNA remodelling helicase
Answer
  • Ruv B/ Reg G
  • PCRA
  • Type 1 Restriction Enzymes
  • Mfd

Question 19

Question
Helicases are divided into seven superfamilies based on primary structure, and then 3 structural classes
Answer
  • True
  • False

Question 20

Question
The two structural classes are monomers and dimers
Answer
  • True
  • False

Question 21

Question
All helicases contain a Rec B fold
Answer
  • True
  • False

Question 22

Question
EVERY helicase molecule contains which of the following?
Answer
  • An ATP binding site
  • An NTP binding site
  • A separate polynucleotide binding site
  • A GTP binding site
  • A linked polynucleotide binding site

Question 23

Question
The _TP binding site and the nucleotide binding site on a helicase are allosterically linked
Answer
  • True
  • False

Question 24

Question
Type A helicases (like PCRA) travel in which direction?
Answer
  • 3' > 5'
  • 5' > 3'
  • Both ways

Question 25

Question
Rec D is a Type 2 helicase- in which direction does it travel?
Answer
  • 5' > 3'
  • Both ways
  • 3' . 5'

Question 26

Question
Rec BCD is a bipolar helicase
Answer
  • True
  • False

Question 27

Question
In a bacterial Holliday Junction with a stalled replication fork, what is required to allow replication to continue?
Answer
  • RuvB
  • ATP
  • PRCA
  • GTP

Question 28

Question
If Holliday Junctions cannot be repaired, they lead to a cruciform structure
Answer
  • True
  • False

Question 29

Question
What is the slowest rate of movement of a helicase?
Answer
  • 10 bp/sec
  • 8 bp/sec
  • 12 bp/sec

Question 30

Question
Rate of helicase movement is dramatically dependent on protein partners
Answer
  • True
  • False

Question 31

Question
The fastest known helicase moves around 4000 bp/sec
Answer
  • True
  • False

Question 32

Question
Define Helicase Processivity
Answer
  • How fast it moves along the DNA/RNA
  • How far it can move before it falls off
  • How far it moves per substrate hydrolysis

Question 33

Question
Helicases can move around 10-30,000 base pairs before falling off depending on the helicase (and it's protein partners)
Answer
  • True
  • False

Question 34

Question
Step size is a theoretical limit due to the entropy of NTP hydrolysis
Answer
  • True
  • False

Question 35

Question
Step size is the theoretical avg no of bp unwound per NTP hydrolysis cycle
Answer
  • True
  • False

Question 36

Question
The limit on step size = Energy required to melt the bp x step size
Answer
  • True
  • False

Question 37

Question
What is the experimental limit of step size?
Answer
  • 0.3-3 bp
  • 0.5- 5bp
  • 0.7- 7 bp

Question 38

Question
What is this image showing?
Image:
Inchworm_Movement_Model (image/png)
Answer
  • The 'Inchworm' helicase movement model
  • The 'active rolling model'

Question 39

Question
Which of the following is believed to be the unwinding mechanism used by helicases?
Answer
  • Passive- DNA is frayed by heat and the translocation occurs in the presence of ATP
  • Active- ATP activates molecules that bind to and actively distort DNA before ATP dependent translocation can occur

Question 40

Question
PCRA is made of how many domains?
Answer
  • 4 - 1A/B & 2A/B
  • 2 - 1A & 2A
  • 6 1A/B, 2A/B & 3A/B

Question 41

Question
PCRA activity is dependent on its protein partners
Answer
  • True
  • False

Question 42

Question
PCRA is an ATPase with...
Answer
  • A 3' > 5' polarity
  • A 5' > 3' polarity
  • A low rate of 30 bp/sec
  • A high rate of 300 bp/sec
  • A low processivity of 10 bp/sec
  • A high processivity of 100 bp/sec
  • A step size of 16 bp/ATP
  • A step size of 6 bp/ATP

Question 43

Question
The conserved Helicase motifs of PCRA are in the accessory domains
Answer
  • True
  • False

Question 44

Question
Aromatic stacking occurs between the inserted aa and bp
Answer
  • True
  • False

Question 45

Question
Which of the following will bind to the DNA
Answer
  • Tryptophan
  • Phenylalanine
  • Tyrosine
  • Histidine

Question 46

Question
The complex of PCRA-DNA remains the same during ATP binding and ATP hydrolysis
Answer
  • True
  • False

Question 47

Question
Duplex distortion in the PCRA substrate complex suggests a Passive unwinding system
Answer
  • True
  • False

Question 48

Question
Partner proteins are required by PCRA for which processes?
Answer
  • Loading
  • Unwinding
  • Activation
  • Catalytic modification

Question 49

Question
Hexameric helicases can be part of the replisome
Answer
  • True
  • False

Question 50

Question
Hexameric helicases have a toroidal strcture to confer high processivity
Answer
  • True
  • False

Question 51

Question
ATP binds where on hexameric helicases?
Answer
  • To the pockets present in each monomer
  • To the pocket made by the interaction of all 6 monomers

Question 52

Question
ssDNA is bound in the central channel to a 'spiral staircase' of bining loops
Answer
  • True
  • False

Question 53

Question
ATP binding pocket changes _ around the ring
Answer
  • Sequentially- one at a time
  • At the same time
  • Sequentially- two at a time

Question 54

Question
ATP binding correlates with loop hight in the central channel
Answer
  • True
  • False
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