Week 4

Question 1

Q1: What do transcription factors do?

Answer 1

A1: They help RNA polymerase bind to the promoter and start transcription.

Question 2

Q2: What’s the difference between activators and repressors?

Answer 2

Activators increase transcription by helping RNA polymerase bind.

Repressors block transcription by preventing RNA polymerase from binding.

Question 3

Q3: How can a regulatory sequence far from a gene still control it?

Answer 3

DNA can loop so distant enhancers/silencers can interact with transcription factors near the promoter.

Question 4

Q4: How does transcriptional regulation differ between prokaryotes and eukaryotes?

Answer 4

Prokaryotes: Simple, often use operons, fast response.

Eukaryotes: Complex, involves enhancers, silencers, chromatin changes.

Question 5

Q5: What is negative and positive control in prokaryotic operons?

Answer 5

Negative control: A repressor blocks transcription.

Positive control: An activator boosts transcription.

Question 6

Q6: What is histone modification?

Answer 6

A6: Chemical changes to histones (like acetylation) that loosen/tighten DNA, affecting gene access.

Question 7

Q7: What is DNA methylation?

Answer 7

A7: Methyl groups are added to DNA, usually silencing genes by tightening the DNA structure.

Question 8

Q8: What are enhancers and promoters in eukaryotic transcription?

Answer 8

A8:

Promoters: Start site for transcription.

Enhancers: Distant DNA elements that boost transcription when bound by activators

Question 9

Q9: How does RNA processing regulate gene expression?

Answer 9

Alternative splicing: Different proteins from the same gene.

5’ cap and poly-A tail: Help stability and translation.

Question 10

Q10: What is RNA interference (RNAi)?

Answer 10

A10: Small RNAs (like siRNA or miRNA) bind mRNA to block translation or cause degradation.