Mechanism of HR in Human Cancers

Play an AI-generated podcast conversation about this lesson

Which repair mechanism is specifically designed to correct chemically modified bases in DNA?

Mismatch Repair (MMS)

Nucleotide Excision Repair (NER)

Homologous Recombination (HR)

Base Excision Repair (BER) (correct)

What type of DNA damage is primarily repaired by Nucleotide Excision Repair (NER)?

Bulky lesions like Thymine-Thymine dimers (correct)

Double-strand breaks

Single-strand breaks

Chemical changes in bases

Which repair mechanism is responsible for detecting and correcting errors that occur during DNA replication?

NHEJ

Base Excision Repair (BER)

Homologous Recombination (HR)

Proof-reading (correct)

What is one of the common sources of DNA damage leading to Thymine-Thymine dimers?

Reactive Oxygen Species Signup and view all the answers

During DNA replication, which repair mechanism helps in joining broken DNA ends?

Homologous Recombination (HR) Signup and view all the answers

Which process can lead to the conversion of cytosine (C) to thymine (T) in DNA?

Deamination Signup and view all the answers

Which repair mechanism focuses on correcting errors after DNA has been synthesized?

Proof-reading Mismatch Repair (MMS) Signup and view all the answers

What is the first step in the repair of double-strand breaks (DSB) through homologous recombination (HR)?

5’ end digestion to leave 3’ recombinogenic ends Signup and view all the answers

Which repair mechanism involves the removal of chemically modified bases to prevent point mutations after replication?

Base Excision Repair (BER) Signup and view all the answers

What is the function of DNA glycosylase in the Base Excision Repair (BER) mechanism?

Marking the damaged base with a sugar Signup and view all the answers

Which proteins' mutations can potentiate human cancers by affecting homologous recombination repair?

BRCA-1 and BRCA-2 Signup and view all the answers

In double-strand break repair (DSB), which process involves DNA strand exchange between separate DNA molecules?

Strand invasion Signup and view all the answers

Which repair mechanism is responsible for repairing Thymine-Thymine dimers induced by U.V. light?

Nucleotide Excision Repair (NER) Signup and view all the answers

What is the main function of Xeroderma pigmentosum genes in the repair of DNA damage?

Recognizing Thymine-Thymine dimers Signup and view all the answers

What is the final step in the repair of double-strand breaks (DSB) through homologous recombination (HR)?

Resolution of the Holiday Junction Signup and view all the answers

Individuals with Xeroderma pigmentosum have a higher predisposition to which types of cancer due to their DNA repair defects?

Melanomas and Squamous cell carcinomas Signup and view all the answers

Which repair mechanism involves a proofreading process to correct errors in DNA replication?

Mismatch Repair Signup and view all the answers

In E.coli, approximately how many bases are wrongly matched during replication?

$1$ base every $10,000$ Signup and view all the answers

In homologous recombination, what is the term used for the cleavage and ligation process that resolves the Holiday Junction?

Resolution Signup and view all the answers

Which gene mutations can lead to an inherited susceptibility to breast cancer?

BRCA-1 and BRCA-2 Signup and view all the answers

Which step involves the opening of the DNA duplex in the Nucleotide Excision Repair (NER) pathway?

Recognition of the dimer Signup and view all the answers

'Glycosylation' by DNA glycosylase marks the chemically modified base with what?

A sugar Signup and view all the answers

Which protein cleaves off the modified base as part of the Base Excision Repair (BER) mechanism?

APEI endonuclease Signup and view all the answers

What is the primary reason for the low mutation rate of 1 every 100 million bases?

Proof-reading activity of DNA polymerase Signup and view all the answers

Which repair pathway fixes mistakes that have escaped the proofreading activity of DNA polymerase?

Mismatch Repair Pathway (MMR) Signup and view all the answers

What is the most serious form of DNA damage discussed in the text?

Double strand breaks (DSB) Signup and view all the answers

Which repair mechanism is prone to errors and is the most common form in mammalian cells?

Non-homologous End Joining (NHEJ) Signup and view all the answers

Which repair pathway is more accurate and only possible when homologous sequences are available?

Homologous Recombination Repair (HR) Signup and view all the answers

Which step follows the recognition of double strand breaks by Ku in the NHEJ repair mechanism?

Recruitment of DNA-PKcs by Ku Signup and view all the answers