1. Changes in the nucleotide sequence of DNA or mRNA
Mutations
Changes in the nucleotide sequence of DNA or mRNA

2. Mutations
Changes in the nucleotide sequence of DNA or RNA that code for a protein
Mutations are caused by mutagens (means “to generate a mutation”)
Examples:
UV Radiation
Cigarette Smoke
Viruses
Chemicals: Laboratory, pesticides, insecticides

3. Point Mutations
One nucleotide base is replaced with another (A single nucleotide mutates thus affecting one codon.) It’s like changing one “word” in a DNA sentence.

4. Silent Point Mutation For Example
This is a harmless mutation. Since many amino acids have multiple codons, it is possible that a mutated codon will still translate into a correct amino acid.
For Example
Original Sequence: G A A  G A G
mRNA: C U U  C U C
Amino Acids: Leu  Leu

5. Missense Point Mutation
This mutation changes the amino acid coded for (MIStake). This is seen in the mutation that causes Sickle Cell Anemia
For Example
Original Sequence: C T T  C A T
mRNA: G A A  G U A
Amino Acids: Glu  Val
Glutamate Or glutamic acid becomes Valine

6. Sickle Cell Anemia

8. Frameshift Mutations
These mutations alter the codon sequence and shift the ‘reading frame’ (A reading frame is a set of 3 consecutive nucleotides (codon) read in the 5’  3’ direction).
It’s like changing the DNA “sentence.” Frameshift mutations are normally very serious. If the codons aren’t read correctly, they will be translated into incorrect amino acids and make nonfunctional proteins.

9. Insertion: adding nucleotides to the sequence
Original sequence: THE BIG TAN DOG RAN
Original with Insertion: THE BOI GTA NDO GRA N
For Example
Original Sequence: CAT TGA  CAT ATG A
mRNA codons: GUA ACU  GUA UAC U
Amino Acids: Val Thr  Val Tyr --

10. Deletion: taking nucleotides out of the sequence
Original sequence: THE BIG TAN DOG RAN
Original with Deletion: THE BGT AND OGR AN
For Example:
Original Sequence: CAT TGA  CTT GA
mRNA codons: GUA ACU  GAA CU
Amino Acids: Val Thr  Glu --

12. Chromosomal Mutations
Mutations in chromosome structure
Deletion: sections of the chromosome are missing
Duplication: sections of a chromosome are repeated

13. Mutations in Chromosome Number
Monosomy: only one copy of a chromosome
Turner Syndrome: when a female has only one X chromosome. Females with this condition have short stature, are sterile and have other physical abnormalities.

14. Trisomy: one extra copy of a particular chromosome (three copies total)
Down Syndrome (trisomy 21): mental retardation, short stature, wide set eyes
Occurs in about 1 in 691. Most individuals live to adulthood, but may have shorter lifespan than average

15. Who is Affected? Somatic Cells Gametes
If a mutation happens in a body cell, only the person that the mutation occurred to will be affected
Mutations in body cells can lead to cancer
Gametes
If a mutation happens in a sex cell, only the organism created from that sex cell will be affected.
Mutations in sex cells affect future generations and this is a cause of evolution, i.e. change in DNA over time