Nucleotides and Lipids

Question 1

What are the two types of Nucleic Acid in Living Cells?

Answer 1

1. Deoxyribonucleic Acid(DNA)
2. Ribonucleic Acid(RNA)

Question 2

What are Nucleic Acids made from?

Answer 2

Nucleic acids are polymeric molecules made up of monomeric units called nucleotides

Question 3

When nucleotides are linked together, what is formed?

Answer 3

Nucleotides link together to form polynucleotide chains.
In RNA these can be thousands of units in length
In DNA these can be millions of units in length

Question 4

What are the components of a DNA nucleotide?

Answer 4

Phosphate
Base
Sugar

Question 5

What is the sugar component of a nucleotide?

Answer 5

The sugar component of the nucleotide is a pentose

Question 6

Where are the nitrogenous bases attached to one the sugar?

Answer 6

The nitrogenous base is attached to the 1’-carbon of the sugar

Question 7

What are the double ring purines?

Answer 7

Adenine and Guanine

Question 8

What are the single ring pyrimidines?

Answer 8

Cytosine, Thymine and Uracil

Question 9

What nitrogenous base is different between DNA and RNA?

Answer 9

Both DNA and RNA contain Adenine, Guanine and Uracil.
DNA also contains Thymine
RNA contains Uracil instead of Thymine

Question 10

What bond joins the base to the sugar?

Answer 10

Beta-N-glycosidic bond
Attached to nitrogen number 1 of the pyrimidine base
Attached to nitrogen number 9 of the purine base

Question 11

What is a molecule compromising the sugar joined to a base called?

Answer 11

A molecule compromising the sugar joined to a base is called a nucleoside

Question 12

What converts a nucleoside into a nucleotide?

Answer 12

The attachment of a phosphate group to the 5’-carbon of the sugar

Question 13

What bonds are Nucleotides joined by?

Answer 13

Nucleotides are joined by a phosphodiester bond

Question 14

How are the nucleotide monomers linked together?

Answer 14

The nucleotide monomers are linked together by joining the alpha-phosphate group, attached to the 5’-carbon of one nucleotide, to the 3’ carbon of the next nucleotide in the chain.

Question 15

What phosphates are ‘cleaved off’ during polymerization of nucleoside triphospate?

Answer 15

Beta-phosphates and y-phosphates

Question 16

What does the phosphodiester bond mean?

Answer 16

‘phospho’ indicates a phosphorus atom
‘diester’ refers to the two ester (C-O-P) bonds in each linkage

Question 17

Which end has not participated in a phosphodiester bond in a DNA trinucleotide?

Answer 17

5’-carbon has not participated in a phosphodiester bond and the beta and y-phosphates are still in place.
This is known as the 5’ end/terminus

Question 18

Which end is the unreacted group in a phosphodiester bond in a DNA trinucleotide?

Answer 18

The unreacted group is the 3’-hydroxyl group.
This is known as the 3’ end or 3’-OH Terminus

Question 19

How are the two polynucleotides arranged in a double helix structure?

Answer 19

The two polynucleotides are arranged anti-parallel to each other (they run in different directions), so that their sugar-phosphate ‘backbones’ are on the outside of the helix structure

Question 20

What is the wide and deep groove in a double helix structure known as?

Answer 20

The Major Groove

Question 21

What is the narrow and less deep groove in a double helix structure known as?

Answer 21

The Minor Groove

Question 22

How many chemical interactions is the helix structure stabilized by?

Answer 22

The helix is stabilized by 2 types of chemical interactions;
1. Hydrogen bonds- which form between the bases that are adjacent to each other
2. Base Stacking- attractive forces between adjacent base pairs which and adds stability to the double helix once the strands have been brought together by hydrogen bonding

Question 23

What bases can be paired together?

Answer 23

Adenine and Thymine
Guanine and Cytosine

Question 24

What is base stacking due to?

Answer 24

Base stacking is due to the attraction between the aromatic rings of the nucleotide bases

Question 25

When is base stacking the strongest?

Answer 25

The attraction is greatest when adjacent rings lie in the same plane, but are slightly displaced vertically, as occurs in a helix structure

Question 26

What is template-dependant DNA synthesis?

Answer 26

Using the sequences of the pre-existing strands to dictate the sequences of new strands

Question 27

What are the forms of the double helix structure?

Answer 27

A-form
B-form
Z-form

Question 28

What could be one reason as to why DNA has different forms?

Answer 28

Rotation around the Beta-N-glycosidic bond, which changes the orientation of the base relative to the sugar and influences the relative positioning of the two polynucleotides

Question 29

Who discovered the double-helix structure of DNA?

Answer 29

James Watson and Francis Crick of Cambridge University

Question 30

What does Sugar Pucker mean?

Answer 30

Sugar pucker refers to the three dimensional shape of the sugar, which can adopt either C2’-endo or C3’-endo configuration. These configurations affect the conformation of the sugar-phosphate backbone

Question 31

What forms can the sugar and base take due to rotation around the Beta-N-glycosidic bond?

Answer 31

Anti
Syn

Question 32

In RNA what are the nucleotide base pairs?

Answer 32

Adenine and Uracil
Guanine and Cytosine