DNA Replication, Repair

Question 0

Leading strand

Answer 0

Strand of DNA double helix that is copied in a continuous fashion

Question 1

Origin of replication

Answer 1

Site on DNA molecule where replication starts

Question 2

Lagging strand

Answer 2

Strand of DNA double helix that is copied in discontinuous fashion

Question 3

Topoisomerase

Answer 3

Class of enzymes that alter the supercoiling of ds DNA

Question 4

Helicase

Answer 4

Enzyme that separates the strands of a DNA double helix

Question 5

Okazaki fragments

Answer 5

A short segment of RNA primed DNA that is synthesized on the lagging strand

Question 6

Antimetabolites

Answer 6

Drug or substance that is an antagonist to or resembles a normal metabolite and thus interferes with its function, usually by competing for its receptors or enzymes
Anti metabolite used as anti cancer agent is 5-fluorouracil (5-FU)

Question 7

Telomerase

Answer 7

Enzyme consisting of RNA and protein components that maintains the ends of the chromosomes by adding specific repeat sequences

Question 8

Polymerase slippage

Answer 8

DNA polymerase can lose its place in a repetitive sequence tract and either leaves our or adds an inappropriate number of repeat units

Question 9

Base excision repair

Answer 9

DNA repair process that involves the excision and replacement of a damaged base

Question 10

Nucleotide excision repair (NER)

Answer 10

DNA repair process involving the excision and resynthesis of a polynucleotide region

Question 11

Homologous recombination

Answer 11

Process involving the recombination between homologous ds DNA molecules

Question 12

Fanconi anemia

Answer 12

Inherited genetic disorder that is cause by mutations in any set of 15 genes involved in DNA repair; cells are hypersensitive to DNA cross linking agents and develop chromosomal aberrations including breakage
Patients show developmental abnormalities in major organ systems including limb malformations, early onset bone marrow failure, high predisposition to cancer

Question 13

Mgmt protein

Answer 13

Protein that repairs O-6 methylguanine by transferring the alkyl group to a cysteine residue in the enzyme which is a suicide reaction and irreversible activates the enzyme. Loss of function of mgmt leads to increased cancer risk.

Question 14

Familial adenomatous polyposis 1 & 2

Answer 14

Caused by defects in BER genes and lead to cancer of the large intestine and rectum

Question 15

Xeroderma pigments a

Answer 15

Defects in NER genes. Patients characterized by extreme sensitivity to sunlight and UV. Autosomal recessive mode.

Question 16

Lynch syndrome

Answer 16

Caused by defects in MMR genes. Aka heriditary nonpolyposis colorectal cancer. Autosomal dominant mode.

Question 17

Microsatellite instability

Answer 17

Specific types of repetitive sequences in the genome can expand or contract in length during replication. If pcr products from tumor and normal tissue differ then there is microsatellite instability. Due to acquired mutations