1. KEY CONCEPT Mutations are changes in DNA that may or may not affect phenotype.

2. A mutation is a change in an organism’s DNA.
Some mutations affect a single gene, while others affect an entire chromosome.
A mutation is a change in an organism’s DNA.
Many kinds of mutations can occur, especially during replication.
A point mutation substitutes one nucleotide for another.
mutated
base

3. Many kinds of mutations can occur, especially during replication.
A frameshift mutation inserts or deletes a nucleotide in the DNA sequence.
(7 min)

4. Genotype: The DNA sequence that determines a specific characteristic
Genotype: The DNA sequence that determines a specific characteristic. Genotypes specify the type of genes people have.
Phenotype: The observable physical or biochemical characteristic of an organism. Some examples include eye color and hair patterns.
Genotype: SOX3
Phenotype: Hypertrichosis

5. Mutations may or may not affect phenotype.
Chromosomal mutations tend to have a big effect.
Some gene mutations change phenotype.
A mutation may cause a premature stop codon.
A mutation may change protein shape or the active site.
A mutation may change gene regulation.
blockage
no blockage

6. Now you try!
DNA: TAC AGA TCA GGG GTG ACT mRNA: AUG UCU AGU CCC CAC UGA A.A.: Met Ser Ser Pro His Stop
DNA: TAC AGG TCA GGT GTG ACT
mRNA: AUG UCC AGU CCA CAC UGA
A.A.: Met Ser Ser Pro His Stop
Do these mutations affect phenotype?
Remember: Amino acid sequence determines protein function! If the A.A. sequence is wrong, the protein may not work (and may even do damage).

7. Some gene mutations do not affect phenotype.
A mutation may be silent (see last slide).
A mutation may occur in a noncoding region.
A mutation may not affect protein folding or the active site.

8. Mutations in body cells (somatic) do not affect offspring.
Ninja Turtles versus X-Men
Mutations in germ cells, or sex cells, can be harmful or beneficial to offspring.
Ninja Turtles versus X-Men
Natural selection often removes mutant alleles from a population when they are less adaptive.

9. Mutations can be caused by several factors.
Replication errors can cause mutations.
Mutagens, such as UV ray and chemicals, can cause mutations.
Carcinogens can cause cancer
Sunlight & Radiation
Charbroiled Meat
Cigarettes
Some cancer drugs use mutagenic properties to kill cancer cells.

10. Cancer What are two reasons human cells divide? Growth and Repair
Cells are told to grow, stop growing, or to “shut down” (apoptosis) through chemical messages
Ex: Human Growth Hormone (HGH) – Tells cells to divide
Cells can stop responding to these signals if their DNA mutates
Cells that keep dividing and ignore apoptosis signals are considered to be cancer
Cancer: Uncontrolled cell division
Video:
Prostate is a gland by the bladder; Only in men
Video starts at “Your body and everything it is made up of cells”