Unit 4 Day 10- Regulating Gene Expression

Unit 4 Day 10- Regulating Gene Expression

By jack morgan

Prokaryotes use the ​General Operon Model

• Operon: the promoter, operator, and the genes they control make up an operon​

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Its important to regulate when we express our genes, but how do organisms do that?​

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There are two types of Operons: ​

• Repressible: ​the operon is active, or "on", under normal conditions, but in certain situations a repressor protein will bind to the operator, turning the gene "off"

• Inducible: the operon is "off" and already bound to a repressor protein, and under certain conditions the repressor will release, turning the gene "on"

Repressible Operon Example:

​tryptophan

​When excess tryptophan is present, it binds to trp repressor protein & triggers repressor to bind to DNA

• blocks (represses) transcription

repressor protein turns the gene "off" by binding two and blocking the RNA polymerase binding site​

Inducible Operon Example:

Lactose​

When lactose is present, binds to lac repressor protein & triggers repressor to release DNA

• unblocks (induces) transcription

​RNA Polymerase

Open Ended

Discuss with your group: why might we want some genes to be repressible and some to be inducible? What's the advantage of each?

1. Regulation of Chromatin Structure

2. Regulation of Transcription Initiation

3. RNA Processing

4. mRNA Degradation

5. Regulation of Translation Initiation

6. Protein processing (structure)

7. Protein degradation

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Now, how do EUKARYOTES regulate their genes?​

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​It's a seven step process

Chromatin is wrapped tightly around Histones​

• no transcription

• genes are turned "off"​

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1. Chromatin Structure​

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3. RNA Processing​

The splicing process of removing introns and linking together exons for a “finished” RNA molecule.

• Introns: Non-coding parts of RNA that are spliced out before the mRNA is translated

• Exons: Coding parts of RNA, which come together and ​form the finished mRNA which will then be translated

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​Introns Leave

Exons Stay​

Any Questions?​