Mutations and Gene Regulation Chapter 12 Sections 4-5

Kinds of Mutations Gene mutations –Frameshift mutations-the remaining codons of the protein have been affected. Insertion (a letter has been added) Deletion (A letter has been removed) –Point mutations-one or a few nucleotides involved Substitutions (One letter is wrong, everything is still in place.)

Mutations cont… Chromosomal –Changes in the number or structure of chromosomes. Most are harmful to the organism Some are beneficial –Polyploidy is when the chromosomes don’t separate properly during meiosis. The result is an offspring with 3N or 4N(extra sets of chromosomes) »This can create a larger, stronger plant.

Gene Regulation RNA polymerase binds to a “promoter” only when beginning. The RNA polymerase will continue through sets of genes that operate together called “operons” –In bacteria- the presence or absence of chemicals cause “feedback” which turns genes on or off.

Eukaryotic Gene Regulation Most eukaryotic genes are controlled individually and have regulatory sequences that are much more complicated than simple operons. Why?

Prokaryotic cells express all genes. (unicellular) Most eukaryotic cells express only part of the genome to cause differentiation. (multicellular) Differentiation is when cells grow differently to perform different functions, such as blood cells, bone cells, or nerve cells. Differentiation is controlled by the hox genes.

Introns and Exons Introns are sections of “Junk DNA” found in the genome that do not code for any proteins Exons are the portion of DNA that actually code for a protein. They are “EX”pressed.