| A | B |
|---|
| when is a gene being expressed? | when it's transcribed and the product is synthesized |
| are all genes expressed at the same time? | no |
| how are genes turned on and off in prokaryotes? | primarily in response to changing environmental factors |
| Jacob and Monod | proposed hypothesis about gene regulation in bacteria |
| operons | a group of genes with related functions |
| structural genes | the genes that code for the protein producers of the operon |
| promoter genes | the genes that promote the movement of RNA polymerase onto the structural genes |
| operator | a region of DNA that acts as an on-off switch for an operon |
| regulator | the part of a gene that continuously makes a repressor protein. not part of the operon, but causes an operon to turn on and off |
| coiling of DNA | chromatin in some regions of a chromosome may be very tightly coiled. when it's tightly coiled, DNA can't be transcribed and genes are inactive |
| methyl groups | small clusters of atoms contained in tightly coiled chromatin |
| regulatory proteins | proteins on eukaryotic genes with the operator section of the genes, which function to control gene expression |
| introns | intervening sequences of bases within genes that are not part of a code for protein |
| exons | short sequences that the DNA that actually codes for the protein is in. lie in between introns |
