Lecture 6

Question 1

Semi-conservative model:

Answer 1

Parent serves as a template and new molecules have one old and one new strand

Question 2

Conservative model

Answer 2

Original helix only serves as a template for synthesis of new helix

Question 3

Dispersive model

Answer 3

Parent fragments serve as templates, assembling old and new parts into molecules

Question 4

______ experiment proved that the Semi-conservative model was correct

Answer 4

Meselson and stahl

Question 5

Describe meselson and stahl experiment:

Answer 5

They made DNA with heavy Nitrogen (15N) and put it in a thick solution. It sunk to the bottom initially. After 20 minutes it became lighter, meaning that the new generations were lighter due to mxing of regualar nitrogen.

After 40 minutes there were two separate bands indicating that some of the new generation was completely 14N while the other half remain half 14N and half 15N

Question 6

The growing strand grows __ to ___ while the Template strand is ordered _ to _

Answer 6

5 -> 3

3 -> 5

Question 7

Helicase is responsible for

Answer 7

unwinding the double helix

Question 8

DNA polymerase 3

Answer 8

creates most of the copied DNA content

Question 9

Telomeres only exist _____ and are responsible for:

Answer 9

in reproductive cells like sperm

Elongating the ends of cells so they don’t degrade a little bit over replication cycles.

Question 10

Termination happens when:

Answer 10

When the replication fork meets the end of a linear cromosome (no more DNA) or when it meets another replication fork (multiple oris’s)

Question 11

Initiation is started by a:

Answer 11

short primer of RNA – a starter strand complementary to the DNA template

Question 12

Primase function:

Answer 12

Adds short RNA primer (to start initiation at the Ori)

Question 13

Ligase functions:

Answer 13

Ligase joins Okazaki fragments and seals nicks in sugar phosphate backbone