DNA

Question 1

What are the 3 components of nucleotides?

Answer 1

A pentose sugar (either ribose or deoxyribose) a phosphate group and an organic base

Question 2

What are the 2 types of nucleic acids?

Answer 2

RNA and DNA

Question 3

Where is the 5’ and 3’ located?

Answer 3

5’ is next to the phosphate group and the 3’ is next to the sugar

Question 4

How many hydrogen bonds link guanine and cytosine?

Answer 4

3

Question 5

How many hydrogen bonds link adenine and thymine?

Answer 5

2

Question 6

What 2 categories can nitrogen bases be placed into?

Answer 6

Purines and pyrimidines

Question 7

What bases is categorised into purine?

Answer 7

Adenine and guanine

Question 8

What bases are categorised into pyrimidines?

Answer 8

Cytosine, thymine and uracil

Question 9

What is the structure of purine?

Answer 9

Double ringed structure, always pairs up with pyrimidines

Question 10

What is the structure of pyrimidines?

Answer 10

Single ringed structure, always pair up with purine

Question 11

What’s a phosphodiester bond?

Answer 11

A bond between a sugar and a phosphate group

Question 12

What enzyme separates the 2 DNA strands?

Answer 12

DNA helicase

Question 13

How does helicase separate the strands?

Answer 13

Break the hydrogen bonds

Question 14

How is a template DNA primer made?

Answer 14

Primase makes a piece of RNA called a primer which acts as a starting point

Question 15

What enzyme matches complementary base pairs to the primer?

Answer 15

DNA polymerase

Question 16

In what direction does DNA polymerase add DNA bases?

Answer 16

From the 5’ to 3’ direction

Question 17

Why can’t the lagging strand be made simultaneously as the other strand?

Answer 17

Runs from 3’ to 5’ direction, so DNA polymerase can only make the strand in small chunks

Question 18

What are the small chunks of DNA bases called on the lagging stand?

Answer 18

Okazaki fragments

Question 19

What happens to the lagging strand after the okazaki fragments are made?

Answer 19

Primase forms a RNA template called a primer, DNA polymerase forms a short row of DNA bases from 5’ to 3’ direction

Question 20

What enzyme removes RNA primers from the DNA strands?

Answer 20

Exonuclease removes all RNA primers and DNA polymerase fills this gap

Question 21

What enzyme seals the fragments of DNA at the very end?

Answer 21

DNA ligase

Question 22

What is the semi-conservative model?

Answer 22

The parental DNA strands separates each one is present in each daughter molecule. One strand of new DNA one strand of original DNA

Question 23

What is the conservative model?

Answer 23

One daughter molecule contains both parental DNA strands the other molecules contains both new DNA strands

Question 23

What is the dispersive model?

Answer 23

The parental DNA is broken down into double stranded segments. The segments reassemble, each individual strand is a patchwork of original and new DNA

Question 24

What model did Stahl support?

Answer 24

Semi-conservative model

Question 25

What model did Meselsohn support?

Answer 25

Conservative model

Question 26

What experiment did Stahl and Meselsohn carry out?

Answer 26

Grew DNA in a E.coli culture containing nitrogen-14 and nitrogen-15. the resulting DNA had one strand nitrogen-14 and the other nitrogen-15, demonstrating semi-conservative replication

Question 27

What joins the nucleotides of the new strands together?

Answer 27

Condensation reactions