32 Questions
What are the two categories of DNA damage faced by the cell?
Endogenous and exogenous
Which factors initiate the DNA damage response (DDR) after the DNA is damaged?
Lesion-specific sensor proteins
What are the majority of the endogenous DNA damage caused by?
Hydrolytic and oxidative reactions
Which agents can cause exogenous DNA damage?
Alkylating agents
What is the DDR in response to DNA damage?
A collection of mechanisms to sense DNA damage, signal its presence, and promote subsequent repair
What happens to DDR factors after DNA damage occurs?
They are assembled at the site of damage in a sequential and coordinated manner
Which category do DNA repair mechanisms fall into?
Repair of damaged bases
What is the first step in most DNA repair processes?
Detection of irregularities in the DNA structure
Which enzyme catalyzes the repair of cyclobutane pyrimidine dimers in DNA exposed to UV radiation?
DNA photolyase
What facilitates the restoration of the normal double-bonded structure of monomeric pyrimidines during enzymatic photoreactivation?
Absorption of visible light
Which enzyme is responsible for the repair of O6-alkylguanine in DNA?
O6-alkylguanine-DNA alkyltransferase
What happens when a single molecule of the O6-alkylguanine-DNA alkyltransferase enzyme accepts a single alkyl group?
It is inactivated
Which pathway is classified as short-patch repair, involving the replacement of only 1 nucleotide?
Base excision repair
Which specific type of alkyl groups is transferred from the reactive sites in the nitrogenous bases to a cysteine acceptor site in the O6-alkylguanine-DNA alkyltransferase enzyme?
(Methyl or ethyl) groups
Which specific DNA lesions are restored to their normal monomeric state through enzymatic photoreactivation?
Cyclobutane pyrimidine dimers
What is the enzyme that catalyzes a single-step reaction for repairing O6-alkylguanine or O4-alkylthymine?
O6-alkylguanine-DNA alkyltransferase
What initiates the DNA damage response (DDR) after DNA damage occurs?
Lesion-specific sensor proteins
Which category of DNA damage arises from the chemically active DNA engaging in hydrolytic and oxidative reactions with water and reactive oxygen species (ROS)?
Internal (endogenous) DNA damage
What are the regulatory mechanisms involved in the recruitment of DDR factors at the site of DNA damage referred to as?
Signal transduction pathways
Which enzyme catalyzes the repair of cyclobutane pyrimidine dimers in DNA exposed to UV radiation?
Photolyase
What is the collection of mechanisms that sense DNA damage, signal its presence, and promote subsequent repair referred to as?
DNA damage response (DDR)
Which agents can cause exogenous DNA damage?
Physical and chemical agents
Which type of DNA repair mechanism involves a series of photochemical reactions that destroy the cyclobutane ring and restore the normal double-bonded structure of monomeric pyrimidines?
Enzymatic photoreactivation
What is the specific site to which alkyl (methyl or ethyl) groups are transferred during the repair of O6-alkylguanine or O4-alkylthymine in DNA?
Guanine acceptor site
Which repair mechanism is classified into two sub-pathways: short-patch repair and long patch repair?
Base excision repair
What is the enzyme responsible for the repair of cyclobutane pyrimidine dimers in DNA exposed to UV radiation?
DNA photolyase
What is the specific nitrogenous base that becomes alkylated at various reactive sites after exposure to synthetic alkylating agents?
Guanine
Which category of DNA damage does repair mechanisms for O6-alkylguanine and O4-alkylthymine fall under?
Endogenous DNA damage
What is the main function of DNA repair pathways?
To effectively remove most DNA lesions
Which pathway involves the replacement of 2-13 nucleotides during the repair process?
Nucleotide excision repair
Which enzyme catalyzes the reaction for repairing O6-alkylguanine or O4-alkylthymine with no cofactor requirement?
O6-alkylguanine-DNA alkyltransferase
Which enzyme is involved in the repair mechanism that restores alkylated guanine to its original state?
O6-alkylguanine-DNA alkyltransferase
Test your knowledge about DNA damage and repair systems, which are essential for retaining genetic information unchanged in cells. This quiz covers internal and external factors that pose destructive forces to DNA, such as metabolic intermediates, reactive radicals, and replication/recombination errors.
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