DNA Repair 💻

Question 1

DNA Damage Long Term Consequences

Answer 1

DNA damage, over time, can result in mutations that may lead to genetic disorders and various long-term impacts on health.

Question 2

Errors of Replication

Answer 2

DNA polymerase can incorporate the wrong base due to tautomerism, leading to errors in replication which are more common during the S phase.

Question 3

Mutagens

Answer 3

Mutagens increase the frequency of mutations by causing mismatches or depurination, including examples like UV radiation and chemical substances.

Question 4

Mismatch repair

Answer 4

Pathway involving genes like MSH2/6, MLH1-3, PMS2 that corrects mismatches in DNA

Question 5

Hereditary Nonpolyposis Colon Cancer

Answer 5

A condition caused by mutations in genes encoding mismatch repair proteins like MSH2, MLH1, PMS1, or PMS2

Question 6

Germline vs Somatic errors

Answer 6

Germline errors can lead to genetic diseases in offspring, while somatic errors can result in cancer

Question 7

Ataxia telangiectasia

Answer 7

A rare disease caused by a defect in ATM gene, leading to increased cancer risk and neurologic symptoms

Question 8

DNA Repair significance

Answer 8

Critical for cell survival, preventing mutations, and reducing cancer risk

Question 9

Repair of DNA Damage

Answer 9

Cells experience DNA damage from normal metabolic processes, which can be efficiently repaired to prevent mutations during replication.

Question 10

Proof-reading

Answer 10

Replication is accurate but errors occur at a low rate due to proof-reading activities of DNA polymerase, crucial in maintaining genetic stability.

Question 11

Oxidative damage

Answer 11

Oxidative damage results from reactive oxygen compounds affecting nucleotide bases, leading to mutations that are repaired by glycosylases.

Question 12

Mismatch Repair

Answer 12

Mismatch Repair is a post-replicative mechanism to remove mismatched bases, crucial for maintaining genomic stability and preventing expansion of repetitions.

Question 13

DNA repair

Answer 13

Process by which a cell identifies and corrects damaged DNA molecules

Question 14

Strand discrimination

Answer 14

Process where cells distinguish between original and new DNA strands by recognizing methylation status

Question 15

BRCA1 and BRCA2

Answer 15

Genes associated with autosomal dominant breast cancer predisposition syndrome involving DNA repair and apoptosis

Question 16

Mutation rate in gametes

Answer 16

Approximately one mutation per ~10^8 nucleotides replicated in gametes

Question 17

DNA Damage Short Term Consequences

Answer 17

DNA damage in cells can lead to reduced proliferation, cell death (apoptosis), and altered gene expression, contributing to aging and diseases like cancer.

Question 18

Molecular Basis of Mutation

Answer 18

Mutations can be spontaneous or induced, with errors of replication mainly occurring during the S phase of cell division.

Question 19

Bloom Syndrome

Answer 19

Bloom syndrome is caused by a defect in a DNA helicase gene, leading to chromosomal instability, characteristic physical features, and increased cancer risk.

Question 20

Deamination

Answer 20

Deamination is the loss of an amine group from a base, such as cytosine deaminating to form uracil, leading to potential DNA mutations.

Question 21

Thymine dimers

Answer 21

Thymine dimers are covalent linkages between adjacent pyrimidine bases caused by UV light, recognized by specific endonucleases for repair.

Question 22

Base Excision Repair

Answer 22

Base Excision Repair involves DNA glycosylases recognizing and removing damaged nucleotides, such as uracil glycosylase targeting uracil for repair.

Question 23

Double stranded breaks

Answer 23

Dangerous DNA mutations that can lead to loss of genetic material or chromosomal rearrangements