Special Topic Lecture 4 Ford

Question 1

Transition Mutation

Answer 1

A point mutation that changes a purine (A or G) to the other purine (A or G) or a pyrimidine (C or T) to the other pyrimidine (C or T)

Question 2

Transversion Mutation

Answer 2

A point mutation that changes a purine to a pyrimidine or a pyrimidine to a purine

Question 3

Base Analog Induced Mutations

Answer 3

For example, BrdU (bromouridine) can pair with either A or G, depending on its chemical state; this is an unusual pairing between U and A or U and G

Question 4

Alkylating Agents Induced Mutations

Answer 4

Mustard gases are an example; they add an alkyl group to bases allowing them to bind to bases they normally wouldn’t, such as Ethylguanine to Thymine

Question 5

Intercalating Agents/Adduct Forming Agents Induced Mutations

Answer 5

Psoralens are an example; upon activation with UV light, these agents form adducts with neighboring pyrimidine residues; joins 2 pyrimidines together that are near each other

Question 6

UV Light Induced Mutations

Answer 6

Irradiation with UV light forms T-T dimers in DNA

Question 7

Ionizing Radiation Induced Mutations

Answer 7

betas, gammas, and x-rays cause electrons to be ejected from an atom, leaving a free radical; these mutagenic properties of ionizing radiation are secondary effects

Question 8

Describe the syn versus anti configurations

Answer 8

The syn configurations seem to have the bulkier constituents are hovering on top of the sugar: in the pyrimidines, the side of the hexagon has the nitrogen groups on it

Question 9

Define tautomer

Answer 9

protonated species

Question 10

What are the observed mutation rates match predictions

Answer 10

transitions: 1 x 10^-4 without the proofreading ability and 5 x 10^-9 with proofreading ability
transversions: 2.5-5 x 10^-6 without proofreading ability and 1-2.5 x 10^-10 with proofreading ability

Question 11

Describe the sickle cell mutation

Answer 11

A change in a Glu to the Val in one codon point mutation (From A to T)

The Valine that is on the side chain is able to fit into the pocket of the neighboring hemoglobin tetramer, which results in the sickle shape (I think idk but it makes sense right?)

Question 12

Describe the process of depurination

Answer 12

To break the backbone, H+ is used. Guanine is cleaved somehow idk (usually by hydrolysis I believe) and then there is an apurinic site

Question 13

Describe hoogsten base pairing (relate it to triplexes because that is what it is typically found in)

Answer 13

Hoogsteen bonds involve three bases; you can have one A/2T or one G/2C

can bind with a free hydrogen that is on the purine and one of the free hydrogens that is present on the pyrimdine