Gene Regulation How does your body know when to make certain proteins? Unit 4 – Chapter 12-5

Gene Regulation Vocab RNA Polymerase:Enzyme that makes an RNA copy of DNA lac Operon: a group of genes that operate together to regulate the production of lactase Lactose: The sugar found in milk

Active Repressor Protein: when lactose is not present the repressor protein is active which means it blocks RNA polymerase from transcribing the lactase gene Inactive Repressor Protein: when lactose is present, lactose fits into the active site of the repressor protein, this prevents the repressor from blocking transcription Gene Regulation Vocab

Operator: region of chromosome in an operon to which the repressor binds when the operon is “turned off” Promoter: RNA polymerase binding site Gene Regulation Vocab

No Lactose Present: Is lactase made? WHY? NO, because the repressor protein is blocking RNA polymerase from copying the gene for lactase

With Lactose Present: What happens to the repressor when lactose is present? Lactose fits into the active site of the repressor protein, which causes it to release from the operator. RNA polymerase can copy the gene.

Lactose present: mRNA is made What will happen after all the lactose is broken down? The repressor protein will grab onto the operator stopping the production of lactase.

lac Operon from Dolan DNA Learning Center z/#content/4dd2fd5aadd2c73bce007d55 z/#content/4dd2fd5aadd2c73bce007d55

Eukaryote and Prokaryote Gene Regulation: 1.___________ generally are not found in eukaryotes 2.Most eukaryotic genes are controlled ___________ and have __________ sequences that are much more ______ than those of the lac operon. Operons IndividuallyRegulatory Complex

Eukaryote and Prokaryote Gene Regulation: 3.A typical feature in a eukaryotic cell is the presence of a gene sequence about 30 base pairs long with a sequence of ___________ or ___________. This sequence is found directly before the starting point for __________________. This region is known as the _______ TATATATATAAA RNA Polymerase TATA Box

Eukaryote and Prokaryote Gene Regulation: 4.What does the TATA box do? Helps position the RNA polymerase by “marking” the spot just before where transcription will take place. 5.How do enhancer sequences affect gene regulation? Allow proteins to bind to DNA opening up tightly packed chromatin so genes can be copied. Also, some use repressor proteins to prevent transcription.

Regulation and Development: 1.What are hox genes? Genes that control organ and tissue development in various parts of the embryo. Determines organism’s basic body plan.

Regulation and Development 2. How important are hox genes? If they are mixed up, an animal’s body plan will be mixed up; In the wrong order.

Regulation and Development 3. What example does the book give as a possilbe mutation for Drosophila if the hox genes are mutated?

Repeat in hox genes: Double Winged Drosophila

Regulation and Development 4. Hox genes are located _______by ______ in a single cluster, arranged in the _________ order in which they are expressed in the body. 5. Draw: Side Exact