Transcription

Question 1

what is transcription

Answer 1

the process of turning the DNA genetic code into RNA

Question 2

how much of the DNA code is for regulating transcription?

Answer 2

5-10%

Question 3

steps of transcription

Answer 3

1. Initiation
2. Elongation
3. Termination

Question 4

TATA box and TFII

Answer 4

• Transcription factors (TFII) first bind regions within the start of a gene, called the promotor region. The promotor region contains the TATA box
• This box is a region that tells TFII that the DNA can be read (i.e. transcribed) nearby. It is rich in thymine and adenine (hence ‘TATA’)

Question 5

RNA polymerase II

Answer 5

Once the TFII binds, it distorts the DNA so that RNA polymerase II (POL II) can bind to the DNA. This polymerase starts to pull apart the DNA strands and transcription begins

Question 6

what is the purpose of capping

Answer 6

• distinguishes mRNA from other types of RNA
• regulation of nuclear export
• prevention of degradation
• promotion of translation

Question 7

termination

Answer 7

• There are cleavage stimulation factors (CstF) and polyadenylation specificity factor (CPSF) that bind to the end of the mRNA.
• These signal the mRNA to stop being transcribed and the POL II dissociates from the complex

Question 8

what is the purpose of polyadenylation

Answer 8

• regulation of nuclear export
• prevention of degradation
• promotion of translation

Question 9

RNA splicing

Answer 9

• removes introns and joins together exons from newly synthesized mRNA
• this step is required to get fully functional mature RNA

Question 10

SPILCEOSOME

Answer 10

• RNA splicing is conducted by the spliceosome
• it consists of many accessory proteins
• specific sequences signal the RNA sequence that is to be removed

Question 11

Alternative RNA splicing

Answer 11

• occurs after initial first RNA splicing

- allows you to get multiple (related) proteins from a single gene

Question 12

epigenetics

Answer 12

• the mechanism by which gene expression is controlled by outside means

Question 13

properties of epigenetic modifications

Answer 13

• they are reversible using special enzymes
• they expose/hide the DNA sequence by adding the modifications
• require ATP hydrolysis

Question 14

gene expression is regulated at many levels

Answer 14

• control rate of transcription
• control RNA splicing
• epigenetic control
• control rate of degradation of transcripts

Question 15

where does the mRNA leave the nucleus from?

Answer 15

• the nuclear pore channels in protein shuttles

Question 16

where does the mRNA go after it leaves the nucleus?

Answer 16

• mRNA enters the translational cytoplasm which contains the rough ER, ribosomes, and golgi body

Question 17

Nissl body

Answer 17

• complex formed by the rough endoplasmic reticulum and the free ribosomes