Molecular Basis of Mutation

Question 1

Ada enzyme

Answer 1

E. coli enzyme that is involved in the direct repair of alkylation mutations

Question 2

AP endonuclease

Answer 2

Enzyme involved in base excision repair

Question 3

DNA glycosylase

Answer 3

Enzyme that cleaves the \beta-N-glycosidic bond between a

base and the sugar component of a nucleotide as part of the base excision and mismatch repair processes

Question 4

DNA photolyase

Answer 4

Bacterial enzyme involved in repair of base dimers

Question 5

DNA repair

Answer 5

Biochemical processes that correct mutations arising from replication errors & effects of mutagenic agents

Question 6

Excision repair

Answer 6

DNA repair process that corrects various types of DNA damage by excising & re-synthesizing a region of polynucleotide

Question 7

MGMT

Answer 7

Enzyme involved in direct repair of alkylation mutations

Question 8

Mismatch repair

Answer 8

DNA repair process that corrects mismatched nucleotide pairs by replacing incorrect nucleotide in daughter polynucleotide

Question 9

Nonhomologous end-joining

Answer 9

Name for double-strand break repair process

Question 10

5-bromouracil (5-bU)

Answer 10

Base analog that can cause mutations by replacing T in a DNA

Question 11

(6–4) lesion

Answer 11

Dimer between two adjacent pyrimidine bases in a polynucleotide,
formed by ultraviolet irradiation

Question 12

Alkylating agent

Answer 12

Mutagen that acts by adding alkyl groups to nucleotide bases.

Question 13

AP (apurinic/apyrimidinic) site

Answer 13

Position in DNA where base component of nucleotide is missing

Question 14

Base analog

Answer 14

Compound whose structural similarity to a base in DNA enables it to act as a mutagen

Question 15

Baseless site

Answer 15

Position in DNA where base component of nucleotide is missing

Question 16

Cyclobutyl dimer

Answer 16

Dimer between two adjacent pyrimidine bases in a polynucleotide, formed by UV irridation

Question 17

Deaminating agent

Answer 17

Mutagen that acts by removi

Question 18

Why is DNA repair important?

Answer 18

Preserving composition of the genome as DNA is constantly being damaged

Question 19

Alagille syndrome

Answer 19

Type of haploinsufficiency on gene for CD339 protein. Causes heart and liver problems.

Question 20

CD339 protein

Answer 20

Involved in cell to cell signalling during embryo development.
Mutation on one causes alagille syndrome

Question 21

Deletion mutation

Answer 21

Mutation caused by deletion of 1 or more base pairs from a DNA sequence

Question 22

Frameshift mutation

Answer 22

Due to insertion/deletion of a base pairs changing frame of translation

Question 23

Insertion mutation

Answer 23

Mutation that arises by insertion of 1 or more base pairs into a DNA sequence

Question 24

Inversion

Answer 24

Mutation involving excision of a portion of DNA followed by reinsertion in same place but in reverse orientation

Question 25

Nonsense mutation

Answer 25

Alteration in nucletide sequence that changes triplet coding for amino acid into a termination codon

Question 26

nonsynonymous mutation

Answer 26

Conversion of codon for 1 amino acid into a codon for a 2nd amino acid

Question 27

Point mutation

Answer 27

Due to single base pair change in DNA

Question 28

Readthrough mutation

Answer 28

Change of stop codon into amino acid codon, so readthrough

Question 29

Second site reversion

Answer 29

Second mutation that reverses effect of previous mutation in same gene without restoring original nucleotide sequence

Question 30

Silent mutation

Answer 30

Change in DNA sequence with no effect on expression/functioning of gene/gene product

Question 31

Synonymous mutation

Answer 31

Change of codon into second codon that specifies same amino acid

Question 32

Transition

Answer 32

Point mutation that replaces a base with same type of base (purine/pyramidine)

Question 33

Transversion

Answer 33

Point mutation involving purine replaced by pyramidine or vice versa

Question 34

Aneuploid

Answer 34

Diploid chromosome set missing one chromosome

Question 35

Carrier

Answer 35

Individual who is heterozygotic for an inherited disease, but does not show phenotype due to normal gene masking effects of mutated gene

Question 36

Haploinsufficiency

Answer 36

Inactivation of 1 of a pair of gene resulting in change of phenotype of mutant organism

Question 37

Monosomy

Answer 37

Presence of single copy of pair of chromosomes in normally diploid nucleus

Question 38

Philadelphia chromosome

Answer 38

Abnormal chromosome due to translocation between chromosomes 9 and 22, a common cause of chronic myeloid leukaemia.

Question 39

Trisomy

Answer 39

Presence of 3 copies of a chromosome in a nucleus that is otherwise diploid.

Question 40

Direct repair

Answer 40

Enzyme comes in and directly repairs damaged DNA

Question 41

Excision repair

Answer 41

Can repair UV damage, etc. Area around damage is removed and replaced by resynthesized DNA

Question 42

Mismatch repair

Answer 42

Can repair base pair mistakes, etc. Area around damage is removed and replaced by resynthesized DNA

Question 43

Nonhomologous end joining

Answer 43

Clear cut in DNA causing strands to come part. due to radiation or chemicals.

Question 44

ADA enzyme

Answer 44

Enzyme in E.Coli which directly repairs DNA damaged by alkylation in position 4 of T and position 6 of G

Question 45

MGMT enzyme

Answer 45

Enzyme in humans, which directly repairs DNA damaged by alkylation at position 6 of G

Question 46

Molecular cloning

Answer 46

Cutting, joining and propagating recombinant DNA

Question 47

True or False? Factor Xa is a human clotting factor of great therapeutic value to those who suffer from clotting disorders. To Maintain its biological activity it must be glycosylated (sugar groups must be added). It can be manufactured at high volume using bacteria as host.

Answer 47

False The protein requires post-translational modification which cannot be done by bacterial hosts therefore the protein must be made by over-expressing in mammalian cells.

Question 48

Ligation

Answer 48

Joining of two DNA strands or other molecules by a phosphate ester linkage.

Question 49

Non-coding DNA

Answer 49

Introns Spacer DNA Regulatory DNA Repetitive DNA sequences