Transcription

Question 1

RNA Polymerase 1,2,3 synthesizes..

Answer 1

1. rRNA
2. mRNA
3. tRNA

Question 2

General mechanism

Answer 2

1. 5’ to 3’ direction

2. Doesn’t need primer -> RNA polymerase

Question 3

How is transcription initiated?

Answer 3

Proteins, TF’s, bind to boxes in promoter regions to initiate transcription. The closer, the stronger it is at initiating

Question 4

Core promoter region

Answer 4

Closest to start of transcription

Question 5

Proximal control

Answer 5

Further away from transcription

Question 6

Eukaryotic promoters

Answer 6

1. TATA Box 25 bp upstream

2. CAAT Box 80 bp upstream

Question 7

General Eukaryotic TF’s

Answer 7

Initiate a standard level of transcription but not sufficient enough for immune response or development -> generally bind to TATA box

Question 8

Additional Eukaryotic TF’s

Answer 8

Bind further along promoter region -> proximal

Enhancer regions interact with TF which cause general TF’s to bind to TATA box

Question 9

TF’s contain at least 2 domains

Answer 9

1. DNA binding domain -> lac or trp, helix turn helix proteins, homeodomain proteins or CRP proteins
2. 1 or more activation domains

Question 10

3 key processes to making mRNA

Answer 10

1. Capping
2. Splicing
3. Polyadenylation

Question 11

Outline the process of capping

Answer 11

1. 7-methylguanoisne added onto nucleotide chain
2. 5’ to 5’ binding in polynucleotide chain
3. This protects ends from degradation by polymerase
4. Cleavage at poly(A) site

Question 12

Poly-adenylation

Answer 12

Addition of a poly(A) tail to mRNA after cleavage. The poly(A) tail consists of 100-250 adenosine monophosphates

Question 13

Splicing occurs after

Answer 13

Poly-adenylation

Question 14

Eukaryotic gene expression

Answer 14

1. Monocistronic
2. Trans factors bind to cis elements
3. Cell-specific factors ensure appropriate temporal and spatial gene expression

Question 15

Prokaryotic gene expression

Answer 15

1. Polycistronic

2. -10 to -35 bp (prigno box region) upstream initiates transcription

Question 16

Outline Hybridisation techniques

Answer 16

1. Start with mRNA -> often reverse transcribed
2. cDNA
3. Microarrays

Question 17

Microarrays

Answer 17

1. Target DNA -> replicate gene sequence fragments
2. Probe is fluorescently labeled cDNA made from mRNA
3. 2 different populations or treatments hybridized to same DNA chip simultaneously

Question 18

How are microarrays useful in studying disease?

Answer 18

They allow a view of the sequence where mutation has occured