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

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 http://teachercenter.insidecancer.org/p/920

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

Eukaryote and Prokaryote Gene Regulation: 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 _______ TATATA TATAAA RNA Polymerase TATA Box

Eukaryote and Prokaryote Gene Regulation: What does the TATA box do? Helps position the RNA polymerase by “marking” the spot just before where transcription will take place. 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: 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 is the hox gees are mutated?

Repeat in hox genes: Double Winged Drosophila

Regulation and Development Side 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