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.

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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.

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

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

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

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

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