Gene Expression

Question 1

What are the three possible levels of gene regulation?

Answer 1

1. Transcription
2. Post-transcription
3. Post-translation

Question 2

Bacterial genes are usually organised into clusters called…

Answer 2

Operons.

Question 3

Genes within an operon are usually involved in the same pathway. True or false?

Answer 3

True.

Question 4

What is polycistronic mRNA?

Answer 4

A single mRNA molecule with multiple genes transcribed.

Question 5

What are the four main components of operons?

Answer 5

1. Regulator
2. Promoter
3. Operator
4. Genes

Question 6

Each operon has multiple promoters. True or false?

Answer 6

False.

Question 7

What type of operon can be easily turned off by regulatory proteins?

Answer 7

Repressible operons.

Question 8

What type of operon can be easily turned on by regulatory proteins?

Answer 8

Inducible operons.

Question 9

What type of molecule turns on/off the regulatory proteins?

Answer 9

Effector molecules.

Question 10

In the lac operon, what acts as the effector molecule?

Answer 10

Lactose.

Question 11

What does the lacZ structural gene encode?

Answer 11

The enzyme beta-galactosidase.

Question 12

What does the lacY structural gene encode?

Answer 12

The enzyme lactose permease.

Question 13

What does the lacA structural gene encode?

Answer 13

The enzyme transacetylase.

Question 14

What is the regulatory component lacI?

Answer 14

The lac repressor.

Question 15

What induces lacI?

Answer 15

Allolactose or IPTG.

Question 16

What is the function of regulatory component O?

Answer 16

Operator site - where the lac repressor binds.

Question 17

What term explains how there can be lactose in the cell to induce the lac operon, while the operon is inactive?

Answer 17

Operon leakiness.

Question 18

What is the trp operon responsible for?

Answer 18

Synthesising tryptophan.

Question 19

Attenuation occurs at the leader sequence. True or false?

Answer 19

True.

Question 20

Attenuation occurs before transcription initiation. True or false?

Answer 20

False.

Question 21

If tryptophan is present, is the repressor bound in the trp operon?

Answer 21

Yes.

Question 22

What are two similar features of bacterial and eukaryotic gene regulation?

Answer 22

1. Regulatory DNA regions.
2. Regulatory proteins.

Question 23

Name three regulatory sequences in eukaryotes.

Answer 23

1. TATA box
2. CAAT box
3. GC box

Question 24

What are the three key components of eukaryotic gene regulation?

Answer 24

1. Regulatory sequences
2. Transcription factors
3. Chromatin remodelling

Question 25

What do basal transcription factors do?

Answer 25

Form the transcription pre-initiation complex.

Question 26

What do activator transcription factors do?

Answer 26

Help RNA polymerase and other TFs.

Question 27

What do repressor TFs do?

Answer 27

Repress RNA polymerase and other TFs.

Question 28

What is the predominant DNA motif in bacteria?

Answer 28

Helix-turn-helix.

Question 29

What is the 'DBD' in transcription factors?

Answer 29

DNA-binding domain.

Question 30

What is the 'SSD' in transcription factors?

Answer 30

Signal-sensing domain.

Question 31

What is the 'TAD' in transcription factors?

Answer 31

Trans-activation domain.

Question 32

Name the gene regulation complex containing helicase, ATPase and kinases.

Answer 32

TFIIH.

Question 33

If histone tails are methylated, are genes expressed?

Answer 33

No.

Question 34

If nucleosomes are packed tightly, histone tails are likely...

Answer 34

Methylated.

Question 35

Histone tail acetylation forms what type of chromatin?

Answer 35

Euchromatin.

Question 36

Heterochromatin has what nucleosome packing?

Answer 36

Tight.