DNA Structure And Function

Question 1

Scientists believed that …. carried genetic information

Answer 1

Proteins

Question 2

Frederick Griffiths 1928 experiment

Answer 2

R and S strains Bacteria
S strain virulent
Mixed heat-killed S and R, mice died
R strain took up a transforming principle

Question 3

Hersey-Chase Experiment

Answer 3

Sample 1= 35 S, only showed in proteins- remained outside of cell&supernatant
Sample 2= 32P, found in DNA and hence in infected bacteria&pellet

Question 4

DNA Structure

Answer 4

Nitrogenous base
Deoxyribose
Phosphate group

A-T
C-G

Question 5

RNA Structure

Answer 5

Nitrogenous base
Ribose sugar
Phosphate group

A-U
C-G

Question 6

Purines

Answer 6

Two ring structure

Question 7

Pyrimidines

Answer 7

Single-ring structure

Question 8

A-T has how many hydrogen bonds?

Answer 8

2

Question 9

C-G has how many hydrogen bonds?

Answer 9

3

Question 10

Phosphate groups are …… charged and hence ….

Answer 10

Negatively

Repel

Question 11

Nucleotides are joined by ….. bonds

Answer 11

Phosphodiester

Question 12

Phosphate groups are the source of…

Answer 12

H+ (acidity)

Question 13

DNA is an antiparallel structure with the strands…

Answer 13

5’-3’

3’-5’

Question 14

3 nucleotide letters

Answer 14

Codon

Question 15

Polymer of nucleotides

Answer 15

Nucleic acid

Question 16

Initiates the translation of the first amino acid

Answer 16

Start codon

Question 17

Central dogma

Answer 17

DNA —> RNA —> PROTEIN

Question 18

Exception of Central dogma Is?

Answer 18

Viruses that use reverse transcriptase to make DNA from RNA

Question 19

Technique based on selective incorporation of chain-terminating deoxynucleotides by DNA polymerase

Answer 19

Sanger sequencing

Question 20

Technique to separate DNA fragments by mass

Answer 20

Gel electrophoresis

Question 21

Each strand of a double helix acts as a template for new, complementary strand

Answer 21

Semi-conservative replication

Question 22

Meselson and Stahl experiment

Answer 22

DNA replication in 14N and 15N (density difference)
1st gen= mixture of both
2nd gen= two distinctive 50/50 bands

Question 23

Enzyme that unwinds the two strands by temporarily breaking parts of the backbone

Answer 23

Topoisomerase

Question 24

Breaks the hydrogen bonds between nitrogenous bases

Answer 24

Helicase

Question 25

Adds RNA primer at leading strand

Adds DNA polymerase III to add nucleotides in 5’-3’ direction

Answer 25

PRIMASE

Question 26

Removes RNA primer and replaces it with newly synthesised DNA

Answer 26

DNA POLYMERASE I

Question 27

When strand is interiors during transcription it creates…

Answer 27

Okazaki fragments

Question 28

Links Okazaki fragments

Answer 28

DNA LIGASE

Question 29

Helps hold DNA polymerase in place whilst nucleotides are being added

Answer 29

Siding clamp

Question 30

Binds to single-stranded DNA to avoid DNA rewinding back

Answer 30

Single-stranded binding proteins

Question 31

DNA sequences at the end of the chromosome involve a single sequence TTAGG repeated

Answer 31

TELOMERES

Question 32

Telomeres act as…

Answer 32

Caps that protect interal regions of chromosomes

Question 33

The 3’ overhang is due to…

Answer 33

Shortening chromosome due to rod-shape and linear

Does not get covered by Okazaki fragments and leaves a gap

Question 34

Complementary RNA is provided for the 3’ overhang by…

Answer 34

TELOMERASE

Question 35

Replaces bases by exonuclease

Answer 35

Mismatch repair

Question 36

Exchange base for another, length unchanged

Answer 36

Substitution

Question 37

Adds a base, length increases

Answer 37

Insertion

Question 38

Removes a base, length decreases

Answer 38

Deletion