Download DNA and Mutations - Effingham County Schools

4.12 DNA and Mutations
Quick DNA Review

Base pairing
Translation and Codons

Codon: 3-nucleotide sequence on mRNA
that codes for an amino acid
Mutations
Mutation: Changes in the genetic material
 A few other notes

99.9% of time = BAD or Neutral
 Does not give you super powers
 No such thing as Kryptonite

2 Types of Mutations

Gene Mutations

Chromosome Mutations
Types of Gene Mutations

Point Mutation:

Mutation that affects a single nucleotide,
usually by substitution.

Frameshift Mutation:
Mutation that shifts the “reading” frame of the
genetic message by inserting or deleting a
nucleotide
 Insertion Mutation
Deletion Mutation

Remember Codons!

Frameshift Mutations:
Codon
THE FAT CAT ATE THE RAT
TEF ATC ATA TET HER AT
Genetic Mutation
Chromosomal Mutations

Chromosomal Mutation:

Change in the number and structure of
chromosomes.
How do mutations occur?
1) Can be inherited
 2) Can be aquired


A) Environmental agents may damage DNA

B) Mistakes occur when cell copies its DNA
Significance of Mutations
Most mutations are neutral (do nothing)
 Most of the rest cause defective proteins =
genetic disorder or death

But . . . (key!!!)
A small % may be beneficial.
 May produce proteins with new, or altered,
activities that can be useful in changing or
different environments.

What happens if mutation is better?