Download Mutations

Mutations
Mutations
• A section of DNA on a chromosome that
directs the making of a specific protein is
called a gene
– Genes control the traits inherited by an
organism
• If a change occurs in a gene or chromosome, a
trait of that organism may be changed
• Any permanent change in a gene or a
chromosome of a cell is called a mutation
Gene mutations
• Point mutation- A change in a single base pair in
DNA
– Causes a change in a single amino acid in the protein for which
the gene codes
Example:
Normal
mRNA: AUG-AAG-UUU-GGC-GCA-UUG-UAA
G was replaced by A
Point Mutation
mRNA: AUG-AAG-UUU-AGC-GCA-UUG-UAA
Gene Mutations continued
• Frameshift mutation- when a single nitrogen base
is added to or deleted from a DNA strand
– Addition or deletion- of a base causes the
sequence of amino acids on the strand to change=
formation of different protein
Chromosomal mutations
• Occur when parts of chromosomes are broken off
and lost during mitosis and meiosis. Also occur
when chromosomes break and rejoin incorrectly.
– Deletion- when part of a chromosome is left out
– Insertion- when a part of a chromatid breaks off and
attaches to its sister chromatid
– Inversion- takes place when a part of a chromosome
breaks out and is reinserted backwards
– Translocation- occurs when a part of a chromosome
breaks off and is added to a different chromosome
Examples of Chromosomal Mutations
• ABCDE FGH
ABCE FGH
Deletion
• ABCDE FGH
ABCBCDE FGH
Insertion
• ABCDE FGH
ADCBE FGH
Inversion
• ABCDE FGH
WXY Z
WXABCDE FGH
Translocation
Y Z
Questions?