Gene Regulation

Gene regulation?

A: A system controlling which genes are expressed (made into proteins).

Essential question (EQ): What controls which genes are used?

A: Gene regulation controls which genes are turned on or off.

3 levels of transcription?

A: 1. Pre-transcriptional control (epigenetics)

2. Transcriptional control

3. Post-transcriptional control

What proteins is DNA wound around?

A: Histones.

Can tightly wound DNA around histones be used to make proteins?

A: No — it cannot be transcribed.

Can loosely wound DNA be used to make proteins?

A: Yes — RNA polymerase can access it.

What do methyl groups do to DNA?

A: They tighten/close DNA → gene turns off.

What do acetyl groups do to DNA?

A: They push DNA apart → gene opens/turns on.

What influences epigenetic changes?

A: Environmental factors.

Are some epigenetic changes inheritable?

A: yes.

What does transcriptional control involve?

A: Systems that interact with genes or RNA polymerase to speed up, slow down, start, or stop transcription.

How much of a chromosome is actually genes?

A: About 2%.

What are examples of noncoding DNA?

A: Introns, tRNA genes, rRNA genes, regulatory DNA, and unknown functional DNA.

What is an enhancer?

A: A DNA region that helps proteins increase transcription.

What is an operator?

A: An on/off switch used by bacteria to control transcription.

What does the gene region do?

A: Codes for the protein.

What are transcription factors?

A: Proteins that help RNA polymerase bind and speed up transcription.

What do activators do?

A: Bind enhancers and help RNA polymerase start transcription.

What do repressors do?

A: Bind the operator or enhancer and block RNA polymerase or activators.

What can mutations in regulatory DNA change?

A: When, where, and how much protein is made.

What controls gene expression after transcription?

A: Processes that destroy or modify RNA before translation.

What is RNAi (RNA interference)?

A: A type of microRNA that destroys suspicious or unnecessary RNA.

How do repressors stop transcription?

A: A repressor binds the operator to block RNA polymerase, preventing the gene from being copied.