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BIOL 308 - Lecture 6 Flashcards | BIOL - Molecular Biology, Quizzes of Molecular biology

Class: BIOL - Molecular Biology; Subject: Biology / Biological Sciences; University: University of Waterloo; Term: Forever 1989;

Typology: Quizzes

2010/2011

Uploaded on 10/09/2011

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TERM 1
BIOL 308 - Lecture 6 Which type of RNA is
very flexible around the secondary and
tertiary structures?
DEFINITION 1
Small RNA
TERM 2
What is Uracil?
DEFINITION 2
Demethylated thymine
TERM 3
DNA functions in replication and transcription
depend on it's ___________. When the helix
becomes locally uncoiled, what happens?
DEFINITION 3
Topological state-Base pairing is interrupted, molecule
exhibits super coiling
TERM 4
What is a "relaxed
molecule"?
DEFINITION 4
Circular DNA without any super helical turn
TERM 5
Besides DNA packaging, what is another use
for super coils?
DEFINITION 5
Reduce the stress induced by twisting of the double helix
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BIOL 308 - Lecture 6 Which type of RNA is

very flexible around the secondary and

tertiary structures?

Small RNA TERM 2

What is Uracil?

DEFINITION 2 Demethylated thymine TERM 3

DNA functions in replication and transcription

depend on it's ___________. When the helix

becomes locally uncoiled, what happens?

DEFINITION 3 Topological state-Base pairing is interrupted, molecule exhibits super coiling TERM 4

What is a "relaxed

molecule"?

DEFINITION 4 Circular DNA without any super helical turn TERM 5

Besides DNA packaging, what is another use

for super coils?

DEFINITION 5 Reduce the stress induced by twisting of the double helix

Strain is released mainly by writhing into

superhelical turns -- this in result is

energetically cheaper than just untwisting it.

Think of the shoelace TERM 7

How often does a supercoil occur in a DNA

molecule?

DEFINITION 7 Every 10 bp TERM 8

Formation of a positive supercoil.

DEFINITION 8 Protein pushes --> infront of protein two strands wrap around eachother more than once every 10 bp --> turns are smaller TERM 9

When does positive supercoiling occur?

DEFINITION 9 When B-DNA is twisting incredibly tightly around its axis TERM 10

Describe negative supercoiling.

DEFINITION 10 Protein pushes --> two strands become wrapped around eachother less than once every 10 bp --> turns are longer

What is the linking #? What is the equation?

-total# of times one strand of closed ds DNA encircles the other strandL = T + WL is constant in unbroken duplex DNA, so any change in T must be met with an equal and opposite change in supercoiling TERM 17

How do you change L?

DEFINITION 17 Break one or both strands of DNA --> wind them tighter/looser --> rejoin ends TERM 18

Most cell DNA are _______ supercoiled.

DEFINITION 18 -negatively TERM 19

How does a cell regulate supercoiling?

DEFINITION 19 Use topoisomerases ex. ProkaryotesTOPO I - nicking-closing enzyme that makes a cut in one strand (relaxing -ve super coil). Does not use ATP and changes L in steps of one.TOPO II

  • relax positive super coil; use ATP, makes a ds cut, passes a duplex DNA through it and reseals the cut. Changes L In steps of two. TERM 20

In the previous example, Prokaryotes were

discussed in relation to topoisomerases. How

about with Eukaryotes?

DEFINITION 20 Topo I - similar to bacterialTopo II - relaxes only supercoiled DNA --> cannot induce super coils