Download Mutations We WILL: You Will:

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 4th 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.