Download 12.4 Mutations

12.4 Mutations
• Changes in the genetic
material
• Mistake in copying,
carcinogens
• Single gene = gene mutation
• Entire chromosome =
chromosomal mutation
Gene Mutations
• Changes in a single gene
Point Mutations
• Changes in 1 or a few nucleotides
• Substitutions – affect no more
than a single amino acid
Frameshift Mutations
• Insertions and deletions
• They shift the reading frame
of the genetic message…
remember bases are read in
groups of three
• Entire protein can be ruined
Chromosomal Mutations
• Changes in the number or
structure of chromosomes
• Can change locations of
genes on chromosomes or
number of copies of some
genes
Chromosomal Mutations
Are mutations harmful?
• Most have little to no effect on
gene expression or protein
function
• Some harmful…genetic disorders
• Source of genetic variability in
species
• Polyploidy – set of chromosomes
does not separate (nondisjunction)
12.5 Gene Regulation
• Expressed gene is one that is
transcribed into RNA
• Regulatory site is where other
proteins binding to the DNA can
regulate transcription
• Promoter is the RNA polymerase
binding site
• Operon is a group of genes that
operate together
Eukaryotic Gene Expression
Differentiation
• Cells become specialized in
structure and function
• Hox genes-control differentiation of
cells and tissues in the embryo