MUTATIONS WE WILL DEFINE MUTATIONS AND DESCRIBE THE

MUTATIONS WE WILL: DEFINE MUTATIONS AND DESCRIBE THE DIFFERENT TYPES YOU WILL: UNDERSTAND THE EFFECTS MUTATIONS CAN HAVE ON GENES

What Is a Mutation? • When cells make mistakes in copying their own DNA, inserting the wrong base or even skipping a base as a strand is put together. • The variations that occur are called mutations • The word mutation comes from the Latin word mutare, meaning “to change” • Mutations are heritable changes in genetic information.

Types of Mutations • There are two basic categories for mutations: 1. Those that produces changes in a single gene (gene mutations) 2. Those that produces changes in the whole chromosome (chromosomal mutations)

• Mutations can occur in both plants or animals.

Gene Mutations • Changes in one or more of the nucleotides are know as point mutations. Point mutations include substitution, insertion, and deletion. • Point mutations generally occur during replication.

Frameshift • Insertions and deletions are referred to as frameshift mutations because they shift the “reading frame” of the genetic message. • Can change every amino acid that follows the point of mutation • Can alter a protein so much that it is unable to perform its normal functions.

Example of a Frameshift Disease • Tay-Sachs Disease • Develops at around 6 months of age • Nerves start deteriorating • Child becomes blind, deaf, and unable to swallow • Death usually occurs before the 4 th year

Chromosomal Mutation • Involve changes in the number or structure of chromosomes • These mutations can change the location of genes on chromosomes and can even change the number of copies of some genes.

• There are 4 types of chromosomal mutations • Deletion • Duplication • Inversion • Translocation

Harmful & Helpful Mutations • The effects of mutations on genes vary widely. Some have little or no effect; some produce beneficial variations. While some negatively disrupt gene function. • Mutations are often thought of as negative as they disrupt the normal function of genes. However, without mutations organisms could not evolve.

Harmful Effects • Some of the most harmful mutations are those that drastically change protein structure or gene activity. • Examples of harmful mutations • Sickle Cell Anemia • Change in RBC shape which deprives the body of oxygen • Cancer

Beneficial Effects • Mutations often produce proteins with new or altered functions that can be useful to organisms in different or changing environments. • Examples: • Mutations have allowed insects to resist chemical pesticide. (Bad for humans, good for insects) • Increase bone density, making fractures less likely • Some mutations can make individuals resistant to the HIV virus that causes AIDS. • Polyploid Plants

Polyploid Plants • Plant and animal breeders often make use of “good” mutations. (more often in plants than animals) • This condition means an organism has an extra set of chromosomes • Polyploid plants are often larger and stronger, good for crop farmers.