2.15 DNA Mutations Flashcards Preview

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Flashcards in 2.15 DNA Mutations Deck (20):
0

Many DNA Polymerase have what type of activity to reduce error?

Exonuclease activity that can go in either direction. This helps Proofread.

1

What is a nonsense mutation

When a termination codon has been placed in the middle of the gene that results in premature termination

2

What mutation is a single amino acid replacement in the protein

Missense mutation

3

What is a frameshift mutation

The addition or deletion of one or two base pairs

4

Describe the DNA damage of Mispairing

One mis-paired base will result in complete change of sequence after multiple replications

5

What type of DNA damage occurs during the lost of the purine base and therefore the nucleotide

Depurination

6

What type of DNA damage occurs when the structure is completely changed to a different base?

Deamination

7

What occurs to the DNA during UV damage?

Produces Thymine dimers which are covalent bonds between adjacent pyrimidines particularly Thymine

8

Name the three strategies of DNA repair

1. Direct Reversal
2. Base Excision Repair
3. Nucleotide Excision Repair

9

What is the product of the deamination of Adenine

Hypoxanthine

10

Deamination product of Guanine?

Xanthine

11

Deamination production of Uracil

Cytosine

12

Deamination product of Thymine

No deamination

13

T or F, A number of carcinogens are mutagenic because they add bulky chemical groups to the DNA which distort the molecule

True

14

Describe Direct Reversal

A methylated base can be demethylated by an enzyme that transfer the methyl group to a cysteine residue within its core

15

Describe Base Excision repair

When a base is damaged through deamination or depurination (etc.), the base is removed as well as the sugar. DNA polymerase adds new nucleotide and DNA ligase seals the hole

16

Describe Nucleotide excision Repair

A group of nucleotides are excised and repaired by DNA polymerase and DNA ligase

17

What type of double stranded DNA break repair methods fixes the break WITHOUT losing nucleotides?

Homologous end joining

18

What occurs during Non-homologous end joint fixing?

The accidental break is cleaned up by Nuclease
Ligase reattaches broken ends
There is a deletion of DNA sequence that was damaged

19

What disease is characterized by a defect in the Nucleotide Excision Repair system

Xeroderma Pigmentosum