Objective

 Understand what mutations are
 Understand how they occur
 Analyze the different types of mutations
 Understand how mutations affect amino acid
sequences and proteins
What we know so far!

 Central Dogma
 DNA is transcribed into RNA, RNA is translated into
proteins
 3 nitrogenous bases give us a codon
 One codon codes for a specific amino acid
 ie. AUG codes for “start” and Methionine
 Peptide bonds hold amino acids together
 Amino acids give us proteins!
What is a mutation?

 If the DNA in the cells inside your entire body were
lined up end to end, they would stretch around the
Earth and Jupiter 60 times in distance!
 Many mechanisms were developed to protect DNA
from change within the cell but mutations still
happens
 Any change in the DNA sequence is called a
mutation!
 Mutations can affect the reproductive cells of an
organism.
 Changes the sequence of the nucleotides within a gene
(sperm or egg cell)
 If this cell takes part in fertilization, the altered gene
becomes part of the genetic make-up.
 Can result in a new trait or a protein that doesn’t work
correctly.
 May (few times) have a positive effect

 Mutation may make organism faster, stronger, and better
to survive in environment.
 Basis of evolutionary theory
Mutations in Body Cells

 Powerful radiation could cause DNA in a nonreproductive cell to change.
 This mutation would not be passed on, but could
cause problems for the individual.
 Impaired function of the cell
 ie. Stomach acid, skin cells
 When a cell divides, the mutation will carry on.
Cancer is a mutation!

 Some mutations can affect the genes that control cell
division!
 Rapid division and growth (result)
 This mutation is known better as cancer.
(uncontrolled division of cells)
 ie. UV radiation in sunlight can change the DNA in
skin cells ; cells produce rapidly, causing skin cancer.
Types of Mutations

 Point Mutation
 A change in a single base pair in DNA.
The first point
mutation did not
result in a change
in the protein.
The second point
mutation caused a
change in the
protein. This was a
stop codon
The third point
mutation coded for
a different protein
as well.
THE DOG BIT THE
CAT
THE DOG BIT THE
CAR
..the meaning of the
sentence changed
due to that one
change in a
word…point
mutations!
Types of Mutations

 Frameshift Mutation
 When a single base is added or deleted from DNA
THE DOG BIT THE
CAT
THE DOG BBI TTH
ECA T
The B was added to
the sentence
resulting in a
scrambled sentence;
frameshift
mutation.
THE DOG BIT THE
CAT
THE DOB ITT HEC
AT
The G was deleted
from the sentence
resulting in a
scrambled sentence;
frameshift
mutation.
Why mutations Matter!

Changes sequence in
nitrogenous bases
May cause change in
amino acid sequence
Function of cell may
be altered
Phenotype (physical
appearance) of trait
may be altered.
Different amino acids
sequence may code
for different proteins
that intended.
Cause of Mutations

 Chemicals
 Asbestos was used to insulate buildings
 Known to cause lung cancer an disease
 UV Rays
Knowledge Check

 What is a mutation?
 What different types of mutations are there?
 Can you describe them?
 Why do mutations matter?