Unit 4 - Ch 13 - Mutations

Question 1

Mutations

Answer 1

Change in the DNA nucleotide sequence

• occur randomly
• usually harmful
• analogous to misspelling words
• are permanent if not lethal to the cell (cell cycle/replication)

Question 2

Point mutation

Answer 2

AKA base-pair substitution, involves a change in only one pair of nucleotides. 
Types:
Missense 
Nonsense
Silent

Question 3

Missense mutations

Answer 3

Replacement of one amino acid for another.

=> cystic fibrosis, sickle c ell anemia

Question 4

Nonsense mutations

Answer 4

Base-pair substitutions that convert an amino acid-specifying codon to a stop codon.
- usually problematic

Question 5

Silent mutations

Answer 5

Base-pair substitutions that have no discernible effect. The mutation does not alter the amino acid sequence.

Question 6

Frameshift mutation

Answer 6

Insert or delete one or more nucleotides of DNA to shift the codon sequence. Results in a bulge in the DNA
- usually serious problems resulting

Question 7

Somatic mutations

Answer 7

Occur in the non-reproductive tissues (somates)

- not transmitted to offspring

Question 8

Germ mutations

Answer 8

Occur in the reproductive tissues (ovaries and testes)

- may be transmitted to offspring (meiosis)

Question 9

Spontaneous mutation rate

Answer 9

Occurs anywhere from 1/1,000 to 1/1,000,000 cells

- humans average 3,000 mutations

Question 10

Mutagens

Answer 10

increase spontaneous mutation rate (10x to 1000x)

=> radiation (gamma, x-ray, UV), chemical compounds (benzpyrene)