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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
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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?
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.