Nucleic Acids

Question 1

name the 2 types of base substituents

Answer 1

Pyrimidines

Purines

Question 2

Are pyrimidines monocyclic or bicyclic?

Answer 2

monocyclic

Question 3

Are purines monocyclic or bicyclic?

Answer 3

bicyclic

Question 4

Define tautomerism

Answer 4

Any reaction involving the intramolecular transfer of a proton

Question 5

Give the 2 purines

Answer 5

Adenine

Guanine

Question 6

Give the 2 pyrimidines

Answer 6

Thymine

Cytosine

Question 7

Whats the tautomerism for adenine?

Answer 7

Amine –> imine

Question 8

Whats the tautomerism for Cytosine?

Answer 8

amino –> imino

Question 9

Whats the tautomerism for Guanine?

Answer 9

keto –> enol

Question 10

Whats the tautomerism for Thymine?

Answer 10

keto –> enol

Question 11

What do nucleotides contain, which nucleosides don’t?

Answer 11

Phosphate bound to 3’ or 5’, or the 2’ in RNA

Question 12

The nucleosides point of attachment to the base is the ____ position of pyrimidines and is the ____ position of purines.

Answer 12

N-1

N-9

Question 13

What is the functional difference of the 2’ R group between DNA and RNA?

Answer 13

The 2’ group of RNA is OH

The 2’ group of DNA is H

Question 14

Why is RNA more reactive than DNA?

Answer 14

The lone pair on the OH acts as a nucleophile

Question 15

Define polymerisation

Answer 15

Linking nucleotides together by phosphodiester bonds

Question 16

What is the most common helical form of DNA

Answer 16

B form - 10 bp per turn

Question 17

In DNA, the negatively charged sugar-phosphate backbone is on the outside protecting the ____ on the inside.

Answer 17

bases

Question 18

The 2 strands are antiparallel to each other due to the ____ bonding between the ____ - _____ base pairs

Answer 18

Hydrogen

Purine - pyrimidine

Question 19

Watson and crick base pairing says that oppositely/same charged regions attract together by _____ bonding

Answer 19

oppositely

hydrogen

Question 20

The double helix provides a chemically stable/unstable environment that protects and stores/releases genetic information

Answer 20

stable

stores

Question 21

DNA can be induced to form the A - form under _____ humidity

Answer 21

low

Question 22

How does the A- form of DNA differ from the B - form?

Answer 22

A - form has a wider, more compressed structure and the base pairs are tilted lying slightly of the axis.

Question 23

What is the helical repeat of A-form?

Answer 23

11 bp per turn

Question 24

Give an example of a prokaryotic genome

Answer 24

E.coli

Question 25

In prokaryotes what shape is DNA?

Answer 25

circular

Question 26

In eukaryotes what shape is DNA?

Answer 26

linear

Question 27

Where is DNA packaged in prokaryotes?

Answer 27

nucleoid

Question 28

Where is DNA packaged in eukaryotes?

Answer 28

nucleus

Question 29

In Eukaryotes the chromosomes have a ____ DNA concentration, and the packing is accomplished by ____ .

Answer 29

high

chromatin

Question 30

In prokaryotes it is observed that there is ___ level of organisation in the nucleoid.

Answer 30

1

Question 31

In eukaryotes it is observed that there is ___ levels of organisation of chromatin.

Answer 31

multiple

Question 32

RNA is an important regulator of gene _______

Answer 32

expression

Question 33

What is a tautomer?

Answer 33

An isomer that differs in position of protons and electrons