Bio1 - Mutation, Cell Cycle, and Cancer

What is a missense mutation?

A change in a single base that alters the mRNA codon and changes the amino acid at that position in the protein product

What is a nonsense mutation?

A change in a single base that alters the mRNA codon to produce a premature stop codon

What is a silent mutation?

A change in a single base that alters the mRNA codon but does NOT affect the protein product

What is a frameshift mutation

A change in DNA that shifts the frame of codons

What is a deleterious mutation?

Any mutation that decreases fitness

What are the cell cycle checkpoints?

G1

G2

M

What are the requirements for passing the G1 checkpoint

Cells pass G1 if:

• Their DNA is not damaged

• They receive signals that keep them in a dividing state (instead of exiting to G0)

• They are an adequate size for cell division

What are requirements for passing the G2 checkpoint

All chromosomes must be replicated properly

DNA must not be damaged

What are the requirements for passing the M checkpoint

• Microtubules must be correctly attached to sister chromatids

• Each cell must have 1 of each chromosome

What is cancer caused by?

Mutations in checkpoints which lead to uncontrolled cell growth

What are tumor suppressors? What do they prevent?

Genes who’s protein products function as regulatory molecules at cell cycle checkpoints, preventing the division of damaged cells