DNA Transcription I

Question 1

Sigma factor

Answer 1

Component of bacterial RNA polymerase that detaches from polymerase when polymerase reaches the start site of transcription and re-binds to polymerase after polymerase reaches the stop site

Question 2

What is sigma factor replaced with in eukaryotes?

Answer 2

general transcription factors

Question 3

What are the factors that affect the rate of synthesis of proteins?

Answer 3

GTFs
Activators
Repressors
Amount of chromatin available for protein synthesis/transcription

Question 4

What is the role of RNA polymerase?

Answer 4

To synthesize all classes of RNA (mRNA, rRNA, tRNA, sNRPs)

Question 5

Roles of the different classes of RNA?

Answer 5

mRNA - code for proteins
rRNA - synthesize proteins
tRNA - adapt mRNA to amino acids
sNRP - excise pre-mRNA & transport protein to ER et alii

Question 6

What do -35, -10, +1 mean?

Answer 6

They are indicators along the DNA strand of when transcription should begin. +1 is the location of the start site. Think of it as a countdown.

Question 7

How do genes fit into transcription?

Answer 7

Genes are the ones being transcribed. That is to say, not all DNA is transcribed into RNA within a cell.

Question 8

What is the name of the strand that is being used to code? What else are needed with it?

Answer 8

Template strand. Ribonucleoside triphosphates

Question 9

What does rifampin do?

Answer 9

Blocks initiation of transcription of TB organism

Question 10

What are unique factors of prokaryotic RNA?

Answer 10

No nucleus
Transcription & translation occur simultaneously (no modifications before-hand)
One polymerase for all proteins
Shorter half-life (2-10 min vs euk 2-24 hrs)

Question 11

How do prokaryotic & eukaryotic genes differ?

Answer 11

Eukaryotic have introns & exons

Question 12

What is an exon?

Answer 12

The piece of the gene that will be coded into RNA

Question 13

Identify the polymerases to their eventual RNA classes

Answer 13

RNA polymerase I - rRNA
RNA polymerase II - mRNA
RNA polymerase III - tRNA

Question 14

What is unique about an enzyme associated with RNA polymerase II?

Answer 14

It is modified along the way by RNA capping, polyandeylation, methylation. This doesn’t happen with tRNA or rRNA

Question 15

What is a key factor in gene regulation in bacteria?

Answer 15

Environment

Question 16

What about activators? (bacteria)

Answer 16

Activators assist in the transcription of bacterial RNA

Question 17

Describe trp and lac repressors (bacteria)

Answer 17

Tryptophan repressor binds to a ligand that inactivates the gene for transcription
Lac operon is a repressor unless lactose is available

Question 18

Why are we so concerned with bacterial RNA transcription?

Answer 18

Because antibiotics can act against bacterial RNA synthesis

Question 19

What is common for gene regulatory proteins?

Answer 19

The fact that they exist in bacteria and humans and work similarly

Question 20

What is a transactivation domain?

Answer 20

Domain where proteins bind to other proteins to allow transcription to occur

Question 21

What is a DNA binding domain?

Answer 21

Region that recognizes and binds to DNA with a gene of interest. These can have several different repeat motifs

Question 22

What is a ligand binding domain?

Answer 22

Region that regulates activity of gene protein by changing the conformation of gene regulatory protein

Question 23

What is unique about regulatory proteins?

Answer 23

Can sense sequence of double-stranded by making protein-to-DNA H-bonds specific to certain DNA

Question 24

What is different about eukaryotic cell growth?

Answer 24

Gene regulation is driven by cell differentiation and growth