Transcript Mutation Notes

Molecular Genetics
Mutations
 A permanent change that occurs in a cell’s
DNA is called a mutation.
 Types of mutations
 Point mutation
 Insertion
 Deletion
Molecular Genetics
Causes of Mutation
 Can occur spontaneously
 Chemicals and radiation also can
damage DNA.
 High-energy forms of radiation, such as X rays
and gamma rays, are highly mutagenic.
Molecular Genetics
Hox Genes
 Hox genes are
responsible for
the general body
pattern of most
animals.
Molecular Genetics
Body-cell v. Sex-cell Mutation
 Somatic cell mutations are not passed on
to the next generation.
 Mutations that occur in sex cells are passed
on to the organism’s offspring and will be
present in every cell of the offspring.
Point Mutation
A Point Mutation is caused when a single base
is changed in the DNA strand.
3 types:
Nonsense: Change causes a Stop codon, shortening the protein
Missense: Changes to a different amino acid, may cause loss of
function
Silent: Base changes codon to the same Amino Acid, so not seen.
Missense
A substitution Mutation
THE BIZ FAT CAT ATE THE
WET RAT
Results: Changes a single Amino
acid
Disease: Achondroplasia
(Dwarfism)
NONSENSE
Substitution
THE BIG RAT
The substitution prematurely stopped the code.
DISEASE: Muscular Dystrophy
Frameshift Mutation
(Insertions and Deletions)
Caused by adding or a deleting a base which
throws off the 3 base coding frame.
Example:
Dowling–Degos Disease
- over pigmentation
- Looks like big freckles
DELETION
Removal of a single base
THB IGF ATC ATA TET HEW ETR AT
Called a frameshift mutation. Throws off the 3 base
reading frame causing a new amino acid
sequence that makes the incorrect protein
DISEASE: Cystic fibrosis
INSERTION
Frameshift mutation: Adding a base – Throwing off
the reading frame
THE BIG ZFA TCA TAT ETH EWE TRA T
DISEASE: CHRON’s DISEASE
DUPLICATION
Extra copy/repeat of a segment of DNA.
THE BIG CAT BIG CAT ATE THE WET RAT
Disease: Charcot-Marie-Tooth Disease
EXPANDING MUTATION
(Tandem Repeats)
A duplication that keeps occurring.
Lengthening the protein until almost
unuseable
THE BIG BIG FAT CAT
THE BIG BIG BIG FAT CAT
THE BIG BIG BIG BIG FAT CAT
DISEASE: Hunnington’s Disease
Real Mutations
Visible mutations usually required more than
one genetic mutation.
Muscle protein gene mutation.
Causes double the muscle tissue
to form resulting in one buff dog…
or super strong German Toddler
Extra Limbs
Color Change Mutations
Extra Fingers Polydactyly
Molecular Genetics