Toxicology: Reactions of Ultimate Toxicants with Target Molecules

Play an AI-generated podcast conversation about this lesson

What is the result of the reaction of toxicants with target molecules?

Impaired cellular function (correct)
Increased ATP production
Enhanced cellular function
Reduced ROS and RNS

What is the effect of xenobiotics on gene expression?

Dysregulation of gene expression (correct)
Increased gene repression
No effect on gene expression
Enhanced gene expression

What is the consequence of the destruction of target molecules?

Cellular proliferation
DNA fragmentation
Cellular dysfunction (correct)
Peroxisome proliferation

How do xenobiotics interact with transcription factors?

By mimicking natural ligands (D) Signup and view all the answers

What is the result of the impairment of internal maintenance?

Sustained rise in Ca2+ (A) Signup and view all the answers

What is the consequence of SH groups interfering with the template function of DNA?

DNA mispairing (A) Signup and view all the answers

What is the primary outcome of the reaction of the ultimate toxicant with the target molecule?

Injury of the target molecule itself, cell organelles, cells, tissue, and organs (A) Signup and view all the answers

What is a characteristic of target molecules that allows them to react with toxicants?

Possession of appropriate reactivity and/or steric configuration (A) Signup and view all the answers

Which type of reaction involves the binding of toxicants with receptors, ion channels, or enzymes?

Noncovalent binding (D) Signup and view all the answers

What is the term for the process by which toxicants alter target molecules in a way that is mechanistically related to the observed toxicity?

Adverse modification (B) Signup and view all the answers

Which type of toxicant reacts with target molecules through electron transfer?

Free radicals (A) Signup and view all the answers

What is the outcome of the dysfunction of target molecules due to toxicant exposure?

All of the above (D) Signup and view all the answers

Which amino acid contains sulfhydryl groups that are prone to oxidation?

Cysteine (B) Signup and view all the answers

What is the process by which damaged proteins are degraded in lysosomes?

Proteolysis (D) Signup and view all the answers

What is the primary function of glutathione (per)oxidase in the repair of lipids?

To reduce peroxidized lipids (D) Signup and view all the answers

What is the primary mechanism of direct repair of DNA damage?

Enzymatic reversal of damage (C) Signup and view all the answers

What is the primary difference between necrosis and apoptosis?

Necrosis involves cellular swelling, while apoptosis involves cellular shrinkage (A) Signup and view all the answers

What is the primary consequence of ATP depletion in a cell?

All of the above (D) Signup and view all the answers

What is the primary mechanism of action of cyanide as an inhibitor of ATP synthesis?

Inhibition of cytochrome oxidase (B) Signup and view all the answers

What is the primary role of Ca2+ in signal transduction?

Regulation of glutamate receptor (D) Signup and view all the answers

What is the primary consequence of sustained rises in intracellular Ca2+?

Activation of PKC (A) Signup and view all the answers

What is the primary function of Ca2+/ATPase in the cell?

To regulate Ca2+ levels in the cytoplasm (D) Signup and view all the answers

What is the reason for the exclusion of Ca2+ from the cytosol?

Its ability to easily precipitate with phosphates (D) Signup and view all the answers

What is the result of increased cytosolic Ca2+ on glycogen synthase?

It renders glycogen synthase inactive (C) Signup and view all the answers

What is the primary target for cell damage from ionizing radiation?

DNA (B) Signup and view all the answers

What is the result of radiation on cell membranes?

It changes the permeability of membranes to various molecules (C) Signup and view all the answers

What is the function of the electron transport system?

To generate ATP through the transport of electrons (A) Signup and view all the answers

What is the role of uncoupling proteins in brown fat?

To generate heat through non-shivering thermogenesis (D) Signup and view all the answers

What is the result of oxidative phosphorylation?

It generates ATP (C) Signup and view all the answers

What is the function of antioxidant defense systems?

To coexist with dioxygen (D) Signup and view all the answers

What is the result of oxidative stress?

It causes lipid peroxidation (C) Signup and view all the answers

What is the role of ROS in carcinogenesis?

They produce mutations in genes and proteins (D) Signup and view all the answers

What is the consequence of the reaction of hydroxylamine with C in DNA?

G-C pair becomes A-T pair (D) Signup and view all the answers

What is the result of the reaction of ethyl methanesulfonate with NH2 groups in DNA?

NH2 groups are converted to keto groups (C) Signup and view all the answers

What is the outcome of the deamination of cytosine and adenine in DNA?

GC→AT and A→G.C (B) Signup and view all the answers

What is the result of the interaction of indirect genotoxic chemicals with DNA?

Strand breaks or damage to the purine or pyrimidine rings (D) Signup and view all the answers

What is the category of mutation that occurs without the introduction of an exogenous mutagenic agent?

Spontaneous mutation (A) Signup and view all the answers

What is the result of the mechanism of base-analog substitution in DNA?

T is replaced by 5-bromoU which binds with G (D) Signup and view all the answers

What is the consequence of the process of inversion in a chromosome?

A segment of the DNA is inverted 180 degrees (D) Signup and view all the answers

What is the outcome of the reaction of a genotoxic substance with DNA that involves base substitution?

Point mutation (A) Signup and view all the answers

What is the result of the interaction of UV radiation with DNA?

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

What is the type of mutation that involves the addition or deletion of base sequences during DNA replication?

Frameshift mutation (A) Signup and view all the answers

What is the result of the activation of c-ras proto-oncogene to oncogene?

Abnormal growth of cells (B) Signup and view all the answers

What is the most frequent type of mutation in the p53 gene in cancer?

Transversions (B) Signup and view all the answers

What is the effect of alkylation at O-6 of G?

It leads to the formation of a tautomeric form that resembles A (C) Signup and view all the answers

What is the result of the interaction of intercalating agents with DNA?

It leads to the formation of frameshift mutations (D) Signup and view all the answers

What is the effect of HNO2 on DNA?

It deaminates bases (C) Signup and view all the answers

What is the result of the reactivity of nucleic acids with high pi bond order?

It is more reactive for addition reactions (C) Signup and view all the answers

What is the effect of UV radiation on DNA?

It leads to the formation of strand breaks (D) Signup and view all the answers