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Flashcards in NAGE 3 Deck (15)
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1
Q

What direction does the RNA chain grow?

A

5’ to 3’ direction

2
Q

What is the antisense strand?

A

The DNA strand getting transcribed.

“Antisense” because opposite of the RNA getting produced

3
Q

Which enzymes carry out transcription?

A

RNA polymerases.

4
Q

What are the 3 types of RNA polymerase?

A
  1. RNA Polymerase 1 - transcribes rRNA genes
  2. RNA Polymerase 3 - transcribes tRNA and 5S RNA genes
  3. RNA Polymerase 2 - transcribes genes encoding proteins into mRNA
5
Q

RNA synthesis has an elongation step. What step does it require to build a transcriptional complex?

A

Initiation step

6
Q

What is the gene promotor?

A

The DNA sequence at which the transcriptional complex assembles.

7
Q

What do transcriptional factors do?

A

Regulate the amount of gene transcription

8
Q
  1. What do Transcriptional activators do?

2. What do Transcriptional repressors do?

A
  1. Activate gene expression

2. Suppress gene expression

9
Q

What does the Basal Transcription Complex do?

A

Produces a low level of transcription, if other transcription factors are missing

It allows RNA Polymerase 2 to be phosphorylated and subsequently engage in transcription

10
Q

Explain how the Basal Transcription Complex works.

A
  1. TF 2D binds to TATA. (TF 2D contains TATA Binding Protein (TBP) and TBP Accessory Factors (TAFs)).
  2. Binding of TF 2D partially unwinds minor groove, and widens minor groove - allows extensive contact with bases.
  3. Unwinding is asymmetrical with respect to TBP-TATA complex - ensures unidirectional transcription
  4. TF 2A and TF 2B bind. TF 2B important as it can bind to TF 2D and RNA Polymerase 2.
  5. RNA polymerase 2 has TF 2F attached. RNA polymerase 2 binds to TF 2B.
  6. TF 2E//H/J binds to RNA Polymerase 2.
  7. TF 2H promotes further unwinding of DNA.
11
Q

How do TFs work?

A

They bind onto TF binding sites and bend DNA. TFs interact with each other and basal transcription complex to regulate transcription.

12
Q

How do TFs facilitate transcription?

A

They help remodel chromatin.

Enzymatic Proteins are recruited that modify histones.

Causes nucleosome acetylation or deacetylation

13
Q

What does hyperacetylation do?

A

Stimulates gene expression

14
Q

What does hypoacetylation do?

A

Stimulates gene repression

15
Q

What are factors affecting TF expression?

A
  1. Cell lineage
  2. TF expression altered by extracellular signals (hormones/GFs/Mechanical Stress, etc)
  3. Mutated TFs important in genetic disorders
  4. Abnormal TF expression found in many human factors.