c18 notes

Only 1.5 % of the human geneome codes for protiens.

It is important for organisms to be able to regulate when genes are turned on so they can be more efficient. prokaryotes-operons...know both tryp and lac operon
Eukaryotes models and the cAMP model.
Differential gene expression
Chromatin must be unwound by DNA Acetylation of histone proteins so transcription can occur.
DNA methylation and Deacetylation can wind it back up to turn off the gene.

Enhancers are DNA codes far from the gene that activators bind to. Activators are transcription factors that bind to proteins in the transcription initiation complex when the DNA strand bends to meet it. This activates the gene. These are cell specific.

Alternative slicing makes different genes depending which are the introns and which are the exons.
How long the poly A tail is affects how long mRNA lasts or how long it is transcribed.

Proteins are modified with sugars to determine which cell will recognize them.

Proteins are broken down by proteosomes that degrade newly made proteins so that they are not expressed forever. The proteins are tagged with Ubiquitone molecules and that targets them for degradation. Some cancers have been found that have made the degradation impossible.

noncoding RNA's control gene expression, some noncoding regions code for RNA molecules that are transcribed and they have a role in gene regulation, such as siRNA's small interfering RNA's. They combine to a complementary sequence and block transcription of a protein.

Differential gene expression is most important during the development of the zygote into an adult (metamorphosis, morphogenisis or development). Cells divide and then differentiate (become specific cells). Cytoplasmic determinants are signaling molecules that determine what kind of cell the embryo cell will become.
Homeotic genes determine the body parts pattern (head abdomen thorax).

oncogenes and proto-oncogenes can trigger cancer (uncontrolled cell growth).
Tumor-suppression genes help prevent uncontrolled cell growth, a mutation of this gene can cause cancer.