Microbial Genetics Pt. 3

Question 1

Point Mutation

Answer 1

when one nucleotide changes

Question 2

Major types of Point Mutation

Answer 2

Substitution: one nucleotide replaced by another

Frameshift: insertion/deletion of nucleotide

Question 3

Major effects of point mutation

Answer 3

Non-sence Mutation

Silent Mutation

Missence Mutation

Question 4

Silent Mutation

Answer 4

• only affects genotype
• not present

-no change in amino acid sequence of polypeptide

• Mutated DNA template strand

Question 5

Non-sence Mutation

Answer 5

-Premature stop codon

• often nonfunctional protein

-Polypeptide synthesis ceases

• Mutated DNA template strand

Question 6

Missence Mutation

Answer 6

• Amino acid changed

-may/may not have effected on function

-slightly different amino acid sequence

• Mutated DNA template strand

Question 7

Chemical Mutagens

Answer 7

Mutagen: agent (chemical/radiation) that causes genetic mutation

-Base analogs

-Intercalating agents

Question 8

Base analogs

Answer 8

Looks like normal bases initially but base pair incorrectly once incorporated

• induce point mutations (protein not functional)

-Looks like a T but pairs with G
-Lots of A-T and G-C point mutations

Question 9

Intercalating agents

Answer 9

-Slips in between adjoining nucleotides

• Bulge in backbone –> polymerase makes mistake –> insertion/deletion of nucleotides

-Frameshifts for ribosome

Question 10

Ionizing Radiation

Answer 10

X-rays and Gamma rays

• Energizes electrons in atoms –> some electrons escape

-Free electrons strike other atoms –> ions –> reacts with DNA –> point mutation

Question 11

Non-ionizing Radiation

Answer 11

UV Light

• induces thymine dimers: covalent bonds between adjacent T’s
• Disort backbone

-In-proper replication