Molecular Biology

Question 1

What are the characteristics of genetic material?

Answer 1

Codes for information to generate an organism, passed to progeny, regulated decoding to suit development

Question 2

What experiment identified DNA as the genetic material?

Answer 2

Hershey-Chase 1952

Question 3

What is the composition of DNA

Answer 3

Pentose sugar group, phosphate group, nitrogenous group

Question 4

Which carbon is the phosphate attached to in DNA

Answer 4

carbon 5

Question 5

Which carbon is the nitrogenous group attached to

Answer 5

carbon 1

Question 6

What is the common structure of purines?

Answer 6

2 rings and 9 atoms

Question 7

What is the common structure of pyrimidines?

Answer 7

1 ring and 6 atoms

Question 8

What are the purine bases?

Answer 8

Adenine and guanine

Question 9

What are the pyrimidine bases?

Answer 9

Cytosine, thymine and uracil

Question 10

What are the differences in groups between DNA and RNA

Answer 10

RNA has ribose and uracil, DNA has thymine and deoxyribose

Question 11

How many hydrogen bonds bind adenine and thymine?

Answer 11

2

Question 12

How is DNA replicated?

Answer 12

Semi-conservatively

Question 13

What enzyme catalyses polymerisation of nucleotides

Answer 13

DNA polymerase

Question 14

Where are incoming nucleotides added?

Answer 14

Free hydroxyl on 3’carbon of the terminal deoxyribose

Question 15

How do DNA strands get their polarity ?

Answer 15

oriented antiparallel to one another

Question 16

Does DNA have a polarity?

Answer 16

YES

Question 17

How is DNA synthesis initiated

Answer 17

replication fork

Question 18

What enzyme separates paired DNA strands?

Answer 18

DNA helicase

Question 19

What direction does DNA synthesis occur in?

Answer 19

5’ prime to 3’ direction

Question 20

Why can new strands not be synthesised continuously?

Answer 20

antiparallel orientation of parental strands and unidirectional orientation of new DNA synthesis

Question 21

What are Okazaki fragments?

Answer 21

short fragment of DNA

Question 22

Which strand synthesises Okazaki fragments?

Answer 22

Lagging strand

Question 23

Describe the synthesis of the lagging strand

Answer 23

discontinuous

Question 24

Describe the synthesis of the leading strand

Answer 24

continuous

Question 25

What is the function of an RNA primer

Answer 25

Extension of primer initiates synthesis of each new DNA strand

Question 26

What is the function of RNA polymerase (DNA primase)

Answer 26

initiates ALL okazaki fragments and ALL leading strands

Question 27

What is the function of DNA ligase

Answer 27

Covalently link okazaki fragments of the lagging strand

Question 28

How is transcription of a typical prokaryotic gene initiated?

Answer 28

by binding of RNA polymerase to DNA sequences in the promoter region

Question 29

Where does the promoter region lie in reference to the transcription site?

Answer 29

Upstream

Question 30

When is transcription terminated in prokaryotes?

Answer 30

when RNA polymerase encounters a terminator region

Question 31

What does the terminator region promote?

Answer 31

Dissociation of RNA polymerase from DNA

Question 32

What is transcription rate limited by?

Answer 32

Frequency of transcription initiation

Question 33

What are the three phases in the transcription of eukaryotic genes?

Answer 33

Initiation, Elongation, termination

Question 34

How is gene expression mainly controlled in organisms?

Answer 34

control of rate of transcription initiation by RNA polymerase

Question 35

Where are exons present?

Answer 35

translated mRNA

Question 36

What happens to introns?

Answer 36

spliced out of primary RNA transcript, DONT appear in mature mRNA

Question 37

What is the function of RNA processing ?

Answer 37

provide control points for regulating gene expression

Question 38

Describe the Hershey-Chase experiment

Answer 38

used viruses with radioactive DNA to infect bacteria, viruses inject genetic material in bacteria, bacteria exhibit radioactivity