Regulation of Gene Expression Chapter 18 Regulation of Gene Expression

I.The Genetics of Bacteria _______________ are the most successful organisms on earth. 1.-contain a circular strand of DNA, the __________. 2.- reproduce asexually by _____ _______. 3.- undergo ________ by taking up foreign DNA. 4._________ transfers DNA via viruses.

5._______ allows bacterial cells to exchange DNA(plasmids) directly.

6._______ are small circular DNA inclusions in bacteria. 7._________ (jumping genes) are DNA fragments that can move from one location to another within a genome.(From nucleoid to plasmid, plasmid to plasmid). These bacterial colonies are colored differently b/c of transposons.

A.Gene Control in _________: 1._______ control gene expression. a. The_______ is the on/off switch. b. The ________is the binding site for RNA polymerase. c. The___________consists of 2+ genes that are required together. d.The _______is a protein that fits in the operator and blocks the RNA polymerase. (turns off) e. The ________ is upstream of the gene sequence.

II. The Structure of Chromatin DNA is packaged into chromatin: 1. DNA wraps around histone proteins creating a _______ (“beads on a chain”). 2. The nucleosome coils to form a _______ fiber (30nm wide). 3. The _____ fiber loops around other proteins. 4. Further folding occurs.

II. Genome Organization At The DNA Level A. Not All DNA Codes For Protein: 1. About ______% of the DNA is noncoding. a. regulatory sequences b. _______ (intervening sequences) c. the majority is ________ DNA

B. Some genes are grouped: 1. __________ families consist of a collection of identical or similar genes. a. these probably evolved from a single gene. b. include genes for _____ products-allow for the production of millions of ____________

C. Genes can be rearranged… 1. _________ are pieces of DNA that move from one location to another. (Barbara McClintock discovered “jumping genes” in corn.) This morning glory should be all purple, The white portion was caused by a ________ that destroyed the purple producing gene.

III. The Control Of Gene __________ A. Gene expression must be controlled precisely to allow for __________ (the divergence of cells to take on special functions). 1. DNA ________ (add -CH3 groups) appears to inactivate DNA transcription. 2. Histone _________ (add -COCH3 groups) causes the histone to change shape and grip the DNA less tightly so that transcription can occur.

3. Transcription ________ via a promoter region and a RNA polymerase allow for further regulation. 4. Gene control can occur after transcription via __________ RNA splicing

Main Point: B. Different cell types are not due to different genes being present, but to ________ gene expression!

IV. The Molecular Biology Of Cancer A. _________ results from changes that effect the cell cycle. 1. Cancer causing genes are called _________. 2. In humans, ________-________ code for the proteins that cause normal cell division. Cancer results when proto-oncogenes _______. Cancer may also result when a tumor-suppressor gene mutates. p53 is an important __________-______________ gene. Halts the cell cycle by binding to _________ Activates suicide genes to cause _________ if DNA is damaged and cannot be repaired.(cell death)