29 Questions
Which repair mechanism is specifically designed to correct chemically modified bases in DNA?
Base Excision Repair (BER)
What type of DNA damage is primarily repaired by Nucleotide Excision Repair (NER)?
Bulky lesions like Thymine-Thymine dimers
Which repair mechanism is responsible for detecting and correcting errors that occur during DNA replication?
Proof-reading
What is one of the common sources of DNA damage leading to Thymine-Thymine dimers?
Reactive Oxygen Species
During DNA replication, which repair mechanism helps in joining broken DNA ends?
Homologous Recombination (HR)
Which process can lead to the conversion of cytosine (C) to thymine (T) in DNA?
Deamination
Which repair mechanism focuses on correcting errors after DNA has been synthesized?
Proof-reading Mismatch Repair (MMS)
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
Which repair mechanism involves the removal of chemically modified bases to prevent point mutations after replication?
Base Excision Repair (BER)
What is the function of DNA glycosylase in the Base Excision Repair (BER) mechanism?
Marking the damaged base with a sugar
Which proteins' mutations can potentiate human cancers by affecting homologous recombination repair?
BRCA-1 and BRCA-2
In double-strand break repair (DSB), which process involves DNA strand exchange between separate DNA molecules?
Strand invasion
Which repair mechanism is responsible for repairing Thymine-Thymine dimers induced by U.V. light?
Nucleotide Excision Repair (NER)
What is the main function of Xeroderma pigmentosum genes in the repair of DNA damage?
Recognizing Thymine-Thymine dimers
What is the final step in the repair of double-strand breaks (DSB) through homologous recombination (HR)?
Resolution of the Holiday Junction
Individuals with Xeroderma pigmentosum have a higher predisposition to which types of cancer due to their DNA repair defects?
Melanomas and Squamous cell carcinomas
Which repair mechanism involves a proofreading process to correct errors in DNA replication?
Mismatch Repair
In E.coli, approximately how many bases are wrongly matched during replication?
$1$ base every $10,000$
In homologous recombination, what is the term used for the cleavage and ligation process that resolves the Holiday Junction?
Resolution
Which gene mutations can lead to an inherited susceptibility to breast cancer?
BRCA-1 and BRCA-2
Which step involves the opening of the DNA duplex in the Nucleotide Excision Repair (NER) pathway?
Recognition of the dimer
'Glycosylation' by DNA glycosylase marks the chemically modified base with what?
A sugar
Which protein cleaves off the modified base as part of the Base Excision Repair (BER) mechanism?
APEI endonuclease
What is the primary reason for the low mutation rate of 1 every 100 million bases?
Proof-reading activity of DNA polymerase
Which repair pathway fixes mistakes that have escaped the proofreading activity of DNA polymerase?
Mismatch Repair Pathway (MMR)
What is the most serious form of DNA damage discussed in the text?
Double strand breaks (DSB)
Which repair mechanism is prone to errors and is the most common form in mammalian cells?
Non-homologous End Joining (NHEJ)
Which repair pathway is more accurate and only possible when homologous sequences are available?
Homologous Recombination Repair (HR)
Which step follows the recognition of double strand breaks by Ku in the NHEJ repair mechanism?
Recruitment of DNA-PKcs by Ku
Explore the recruitment of XLF-XRCC4 and Ligase IV complex in ligation process during homologous recombination repair in human cancers. Learn about how inherited mutations in genes like BRCA-1 and BRCA-2 can potentiate the development of breast cancer.
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