Aim: What are mutations ?

HW #11 read pages 307-308Text Chapter 12

Mutation

• Is a change in the DNA sequence that affect the genetic information. They occur randomly.

• Gene mutation is a change in a single gene on a chromosome

Substitution InsertionDeletion

Gene Mutations

Substitution, Insertion, and Deletion

Go to Section:

Chromosomal mutations

• Involves changes in the number or structure of chromosomes. Chromosomal mutations may change the locations of genes on chromosomes and even the number of copies of some genes

Deletion

Duplication

Inversion

Translocation

 Chromosomal MutationsSection 12-4

Go to Section:

Down’s Syndrome

Trisomy of Chromosome 21

Turner’s Syndrome

In 75 to 80 percent of cases, the single X chromosome comes from the mother's egg because the father's sperm that fertilizes the egg is missing a sex chromosome.

Klinefelter Syndrome

Men and boys with Klinefelter Syndrome have a Y chromosome and 2 X chromosomes.

This is an example of trisomy.

Homologous chromosomes fail to separate

Meiosis I:Nondisjunction

Meiosis II

Section 14-2

Nondisjunction

Go to Section:

Non-disjunction

Mutagenic Agents

Study Finds Genital abnormalities in Boys

• Scientists studying the effects of hormone-mimicking chemicals on humans have reported that phthalates, used in plastics and beauty products and widely found in people, seem to alter the reproductive organs of baby boys. The findings were based on tests of 85 mothers and sons. Mothers with the highest levels in their urine late in their pregnancies had babies with a cluster of effects (2005)

• toxic chemicals in food • Pesticides• Antibiotics• drugs

Food Additives

• The legendary longevity of some packaged foods such as Twinkies, is attributable in part to food additives that stabilize ingredients and prevent spoilage. Additives also enhance the nutrition, flavor, and consistency of foods