L15: Information transfer in cells

Question 1

What is the ‘central dogma’ of molecular biology?

Answer 1

an explanation of the flow of genetic material within a biological system. It involves:

• Replication
• Transcription
• Translation

Question 2

What is the ‘central dogma’ of molecular biology?

Answer 2

an explanation of the flow of genetic material within a biological system. It involves:

• Replication
• Transcription
• Translation

Question 3

Structural differences between RNA and DNA x3

• strandedness
• functional groups
• nucleotides

Answer 3

• DNA is double stranded, RNA is single stranded
• RNA has an OH group at ribose C2, DNA just has an H
• DNA uses thymine, RNA uses uracil

Question 4

What makes RNA unstable and easily degraded?

Answer 4

• OH group means RNA can be attacked by water and undergo hydrolysis reactions

Question 5

What is the difference between purine and pyrimidine bases?

Answer 5

Purine: A and G
Pyrimidine: C, T and U

Question 6

What percentage of our genome is genes?

Answer 6

less than 5%

Question 7

Give examples of some gene regulatory elements. What are they?

Answer 7

promotor sequence: bind TF’s
enhancer sequences: bind TF’s
some make regulatory RNA that doesn’t lead a protein

Question 8

Structural differences between RNA and DNA x3

• strandedness
• functional groups
• nucleotides

Answer 8

• DNA is double stranded, RNA is single stranded
• RNA has an OH group at ribose C2, DNA just has an H
• DNA uses thymine, RNA uses uracil

Question 9

What makes RNA unstable and easily degraded?

Answer 9

• OH group means RNA can be attacked by water and undergo hydrolysis reactions

Question 10

What is the difference between purine and pyrimidine bases?

Answer 10

Purine: A and G
Pyrimidine: C, T and U

Question 11

Give examples of some gene regulatory elements. What are they?

Answer 11

promotor sequence: bind TF’s
enhancer sequences: bind TF’s
some make regulatory RNA that doesn’t lead a protein

Question 12

Introns are removed from primary RNA by…

Answer 12

splicing machinery

Question 13

What is on the 3’ and 5’ ends of DNA

Answer 13

5’ = hydroxyl

3’ trisphosphate

Question 14

What are the basic building blocks for DNA synthesis?

Answer 14

deooxynucleoside trisphosphates (dNTPs)

Question 15

Which direction does the enzyme DNA polymerase work?

Answer 15

5’ to 3’

Question 16

What must there be for DNA polymerase to start? and why?

Answer 16

RNA primer provides a free 3’ end which receives incoming dNTP’s

Question 17

What is the difference between the action of DNA polymerase on the leading and lagging strand?

Answer 17

On the leading strand, DNA polymerase travels from one end to the other in the 5’ to 3’ direction
The lagging strand is in the 3’ to 5’ direction so DNA polymerase replicates the DNA in fragments in the 5’ 3’ direction. These are called okazaki fragments which are later polymerised by ligase

Question 18

Describe what is meant by the replication ‘bubble’

Answer 18

The whole genome cannot be unzipped in order to be replicated. It is there replicated in sections, which look like bubbles

Question 19

How does DNA polymerase proof read?

Answer 19

Adds a base, moves back to check it, excises it if its wrong and then moves on

Question 20

Which direction does RNA polymerase work in?

Answer 20

5’ to 3’

Question 21

What is the predominant level of control in gene expression?

Answer 21

Control of transcription

Question 22

What is it called when more than one ribosomes attaches to a single mRNA?

Answer 22

polyribosome

Question 23

Which three codons are stop codons?

Answer 23

UAA, UGA, UAG

Question 24

The genetic code is redundant. However, which amino acid is coded for by only one codon?

Answer 24

Methionine = AUG

Question 25

What are repeat elements in DNA useful for?

Answer 25

To detect polymorphisms

DNA fingerprinting