Nucleic Acids

Question 1

What kind of sugar is ribose?

Answer 1

Pentose ( 5-carbon)

Question 2

Deoxyribose has its hydroxyl group replaced on which carbon?

Answer 2

2’

Question 3

Which nitrogenous bases are purines?

Answer 3

Adenine and Guanine

Question 4

Which nitrogenous bases are pyrimidines?

Answer 4

Thymine, Uracil and Cytosine

Question 5

Nitrogenous bases are attached to sugars on which carbon

Answer 5

1’

Question 6

Which type of bases are single ring structures?

Answer 6

Pyrimidines

Question 7

Which type of bases are double ring structures?

Answer 7

Purines

Question 8

Why type of bonding links bases to sugars?

Answer 8

Glycosidic

Question 9

On which N atom are pyrimidines linked to sugars

Answer 9

1

Question 10

On which N atom are purines linked to sugars

Answer 10

9

Question 11

What kind of bond connects nucleotides?

Answer 11

Phosphodiester linkage

Question 12

On what C atom does a sugar have its triphosphate group attached?

Answer 12

5’

Question 13

Which groups are cleaved off when nucleotides polymerize?

Answer 13

The beta and gamma phosphate groups of one nucleotide, and the hydroxyl group on the 3’ carbon of the other

Question 14

What is the 5’ end?

Answer 14

There is a triphosphate group on the 5’ carbon of one nucleotide which hasn’t participated in a phosphodiester linkage

Question 15

What is the 3’ end?

Answer 15

The hydroxyl group on the 3’ carbon of a nucleotide at one end of a polynucleotide chain

Question 16

A chromosome is made of very densely packed entrails known as _

Answer 16

Chromatin

Question 17

Chromatin is a large amount of DNA wrapped around proteins called _

Answer 17

Histones

Question 18

Which proteins play a crucial role in packaging DNA very tightly

Answer 18

Histones

Question 19

What is a nuceloside?

Answer 19

A sugar group with a nitrogenous base

Question 20

The hydroxyl group on the 3’ carbon of the sugar tends to interact with phosphate groups because it is a _

Answer 20

Nucleophile

Question 21

The linkage of around 10 nucleotides is a _

Answer 21

Oligonucelotide

Question 22

Give two names for the process of putting together two strands of DNA in a double helix structure

Answer 22

Hybridisation and Annealing

Question 23

Why do bases interact through stacking?

Answer 23

They are aromatic compounds and interact through pi stacking

Question 24

What does it mean to say that DNA is right handed?

Answer 24

It means that clockwise rotation moves the strand away from the observer

Question 25

DNA strands run in opposite directions, they are _

Answer 25

Antiparallel

Question 26

What does it mean to say that DNA is not regular in its shape?

Answer 26

There are deeper and shallower grooves, known as major and minor respectively

Question 27

At how many sites to G and C bases form hydrogen bonds?

Answer 27

3

Question 28

At how many sites to A and T bases form hydrogen bonds?

Answer 28

2

Question 29

What is the typical diameter for a b-form helix?

Answer 29

2.37nm

Question 30

What is the typical pitch of a b-form helix? What does that mean?

Answer 30

3.47nm, 10 base pairs constitute one complete turn in the structure

Question 31

What two phenomena can affect the molecular conformation of DNA/nucleotides?

Answer 31

Sugar pucker, rotation around the beta-N-glycosidic bond

Question 32

Which two conformations can the sugar adopt?

Answer 32

C2’-endo and C3’-endo

Question 33

Dimensions of fibres containing DNA change when _

Answer 33

Exposed to different humidity