ECB Chapter 6

Question 1

What were the three models hypothesized to parental strands and daughter strands were arranged in DNA?

Answer 1

1. ) Dispersive
2. ) Conservative
3. ) Semi-Conservtive

Question 2

What experiment described the arrangement of parental and daughter DNA?

Answer 2

The first experiment allowed them to figure out that it could have not have been conservative because if it were the bands would have been at the top or the bottom and not in between.

To figure out if the dispersive or semi conservative model was correct. They took DNA, heated it to break the hydorgen bonds that separated the strands and then they did the same experiment. The results showed that there was one heavy and one light band, thus indicating that ht semi conservative model was correct.

Question 3

How many links between A and T?

Answer 3

2

Question 4

How many links between C and G

Answer 4

3

Question 5

In what direction are new DNA strands created

Answer 5

5’ to 3’. Meaning that nucleotides are added to the 3’ end

Question 6

What does DNA replication polymerase do?

Answer 6

Adds nucleotides to the 3’ end of the new DNA strand

Question 7

Does DNA polymerase require a primer?

Answer 7

RNA primer is required before DNA polymerase can do its work

Question 8

What is topoisomerase?

Answer 8

Unwinds DNA strand

Question 9

What is helicase?

Answer 9

It breaks the DNA strand

Question 10

What are the two reason that DNA polymerase is so accurate?

Answer 10

1. ) The enzyme carefully monitors base pairing between each incoming nucleotide and the template stand. Only when the match is correct does the DNA polymerase catalyze the addition.
2. ) It can correct itself through proofreading. If the nucleotide that is added is incorrect then the same DNA polymerase that added it cleaves it

Question 11

How many primers does the leading DNA strand require?

Answer 11

Only one RNA primer

Question 12

How many RNA primers does the lagging strand require?

Answer 12

Multiple

Question 13

What puts the RNA primer on the lagging stand?

Answer 13

primase (a type of RNA polymerase)

Question 14

How does primase work?

Answer 14

It adds RNA for about 10 bases. It’s purpose is just to open up 3’ end to the DNA polymerase to attach to.

Question 15

What makes RNA primer?

Answer 15

primase

Question 16

Why is RNA primer necessary?

Answer 16

It gives a 3’ OH group for the DNA polymerase to build off of

Question 17

Why must DNA polymerase work on the 3’ end of the new DNA strand?

Answer 17

Because the proof reading ability of the enzyme would not work in the opposite direction

Question 18

Does DNA polymerase contain separate sites for synthesis and proof reading?

Answer 18

yes, there is a polymerazation site where new nucleotides are added and an editing site where those nucleotides are proof read before the new strand and the template strand are linked.