1. Warm-Up (1/4) Explain how a cell expresses a gene.
On the piece of white paper from the back, answer the following question.
Name
Date
Period
Explain how a cell expresses a gene.

2. 3B.1a: Both DNA regulatory sequences, regulatory genes, and small regulatory RNAs are involved in gene expression.
3B.1a.1: Regulatory sequences are stretches of DNA that interact with regulatory proteins to control transcription.
Illustrative example: promoters
3B.1a.2: A regulatory gene is a sequence of DNA encoding a regulatory protein or RNA.
3B.1c: In eukaryotes, gene expression is complex and control involves regulatory genes, regulatory elements and transcription factors act in concert.
3B.1c.1: Transcription factors bind to specific DNA sequences and/or other regulatory proteins.
3B.1c.2: Some of these transcription factors are activators (increase expression), while others are repressors (decrease expression).
3B.1c.3: The combination of transcription factors binding to the regulatory regions at any one time determines how much, if any, of the gene product will be produced.
4C.2a: Environmental factors influence many traits both directly and indirectly.
Illustrative examples: Effect of increased UV on melanin production in animals

3. Regulation of Eukaryotic Genes
protein
How does a gene know when to start and end?
RNA
DNA

4. Regulation of Eukaryotic Genes
protein
How does a gene know when to start and end?
RNA
DNA

5. Regulation of Eukaryotic Genes
protein
How does a gene know when to start and end?
RNA
DNA

6. Regulation of Eukaryotic Genes
protein
How does a gene know when to turn on and off?
RNA
DNA

7. Regulation of Eukaryotic Genes
Promoters say where and when transcription starts.
protein
RNA
Right here at 3:15!
DNA
regulatory
sequence
coding sequence

8. Regulation of Eukaryotic Genes
Transcription factors bind onto promoters and regulate transcription.
transcription factor
DNA
promoter
coding sequence

9. Regulation of Eukaryotic Genes
They can turn transcription on or off.
transcription factor
RNA
DNA
promoter
coding sequence

10. Regulation of Eukaryotic Genes
They can turn transcription on or off.
transcription factor
DNA
promoter
coding sequence

11. Regulation of Eukaryotic Genes
Activators turn transcription on.
activator
RNA
DNA
promoter
coding sequence

12. Regulation of Eukaryotic Genes
Repressors turn transcription off.
repressor
DNA
promoter
coding sequence

13. Regulation of Eukaryotic Genes
The sum total of activators and repressors determines gene expression.
repressor
activator
Should I stay or should I go?
DNA
promoter
coding sequence

14. Regulation of Eukaryotic Genes
Regulatory genes encode transcription factors.
Transcription factor protein
RNA
DNA
regulatory gene

15. Critical Thinking Question #1
Discuss this question with your partner and write or represent it. I will call on three people to share their partners’ answers.
The gene ATP4A encodes a protein called Gastric Hydrogen Potassium ATPase, which is responsible for releasing acid from the parietal cells lining the inside of the stomach to the inside of the stomach. The genomes (total DNA) of all somatic cells in a person’s body are identical, because they all originated from a single zygote (fertilized egg) through the process of mitosis. Represent (draw, illustrate, make a diagram) showing how parietal cells are different from neurons in the brain in the context of acid secretion.

16. Critical Thinking Question #2
Discuss this question with your partner and write or represent it. I will call on three people to share their partners’ answers.
Explain why it is essential to regulate the expression of topoisomerase and helicase in a cell as it proceeds through the cell cycle and mitosis.

17. 3B.1a: Both DNA regulatory sequences, regulatory genes, and small regulatory RNAs are involved in gene expression.
3B.1a.1: Regulatory sequences are stretches of DNA that interact with regulatory proteins to control transcription.
Illustrative example: promoters
3B.1a.2: A regulatory gene is a sequence of DNA encoding a regulatory protein or RNA.
3B.1c: In eukaryotes, gene expression is complex and control involves regulatory genes, regulatory elements and transcription factors act in concert.
3B.1c.1: Transcription factors bind to specific DNA sequences and/or other regulatory proteins.
3B.1c.2: Some of these transcription factors are activators (increase expression), while others are repressors (decrease expression).
3B.1c.3: The combination of transcription factors binding to the regulatory regions at any one time determines how much, if any, of the gene product will be produced.
4C.2a: Environmental factors influence many traits both directly and indirectly.
Illustrative examples: Effect of increased UV on melanin production in animals

18. Illustrative Example: Melanin Production
transcription factor activated
Probably British.
UV damage
melanin gene

19. Illustrative Example: Melanin Production
Probably British.
RNA
UV damage
melanin gene

20. Illustrative Example: Melanin Production
Protects against more UV damage
melanin
The damage is done, you idiot!
RNA
melanin gene

21. Closure
On the piece of white paper from the back, answer the following question:
Name
Date
Period
Describe how two humans each with identical alleles of the lactase gene can have different levels of lactose intolerance.
Scale 1 – 10