Toxicology Reaction Mechanisms

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What is the result of the reaction of the ultimate toxicant with the target molecule?

Activation of the target molecule's function

Hydrolysis of the target molecule

Injury to the target molecule, cell organelles, cells, tissue, and organs (correct)

Stimulation of enzyme reaction

What type of binding occurs between toxicants and receptors, ion channels, or enzymes?

Covalent binding

Nucleophilic binding

Noncovalent binding (correct)

Electrophilic binding

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

Lack of reactivity

Critical function in the cell

Appropriate reactivity and/or steric configuration (correct)

Inability to bind to toxicants

How can the ultimate toxicant alter the target molecule?

By all of the above mechanisms Signup and view all the answers

What is necessary to identify a target molecule as responsible for toxicity?

All of the above are necessary Signup and view all the answers

What is a possible effect of toxicants on target molecules?

Dysfunction of the target molecule Signup and view all the answers

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

Mispairing Signup and view all the answers

What is the consequence of xenobiotics interacting with promoter regions of genes?

Dysregulation of gene expression Signup and view all the answers

What is the result of peroxidative degradation of cellular components?

DNA fragmentation Signup and view all the answers

What is the consequence of dysregulation of transcription factors?

Inappropriate cell division Signup and view all the answers

What is the result of sustained rise in Ca2+ levels?

ATP depletion Signup and view all the answers

What is the consequence of impaired function of integrated systems?

Cellular dysfunction and relative toxicity Signup and view all the answers

What is the function of thioredoxin in protein repair?

To enzymatically reduce sulfhydryl groups in cysteine Signup and view all the answers

What is the result of ATP depletion in a cell?

All of the above Signup and view all the answers

What is the function of DNA photolyase in DNA repair?

Direct reversal of DNA damage Signup and view all the answers

What is the consequence of necrosis on neighboring cells?

Deleterious effects on neighboring cells Signup and view all the answers

What is the effect of cyanide on ATP synthesis?

Inhibition of cytochrome oxidase Signup and view all the answers

What is the function of glutathione in lipid repair?

Reduction of peroxides in lipids Signup and view all the answers

What is the consequence of Ca2+ accumulation in the cytoplasm?

Precipitation of phosphates Signup and view all the answers

What is the function of chaperone proteins in protein repair?

Refolding of proteins Signup and view all the answers

What is the difference between necrosis and apoptosis?

Apoptosis is active, while necrosis is passive Signup and view all the answers

What is the effect of rotenone on ATP synthesis?

Inhibition of complex I Signup and view all the answers

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

It converts C to a modified base that pairs only with A Signup and view all the answers

What is the outcome of the reaction of ethyl methanesulfonate with DNA?

It converts NH2 groups to keto groups by oxidative deamination Signup and view all the answers

What is the term for the changes in chromosomal structure, such as breaking off of part of a chromosome or translocation of an arm?

Clastogenesis Signup and view all the answers

What is the term for the uneven separation of chromosomes during cell division?

Aneuploridization Signup and view all the answers

What is the result of sugar-base cleavage by ROS?

C→U Signup and view all the answers

What is the result of a triplet code being misread entirely?

A radical change of the protein structure Signup and view all the answers

What is the mechanism of action of base-analog substitution?

It substitutes a similar base during replication Signup and view all the answers

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

Point mutation Signup and view all the answers

What is the most frequently mutated gene in cancer?

p53 Signup and view all the answers

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

Frameshift mutation Signup and view all the answers

What is the result of alkylation of the OH group in phosphate?

Formation of 3-OH and 5-P Signup and view all the answers

What is the effect of intercalating agents on DNA?

They inhibit the action of Topoisomerase II Signup and view all the answers

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

All of the above Signup and view all the answers

What is the term for the process of converting an alkyl protein derivative to a hydroxy derivative?

α-amidation pathway Signup and view all the answers

What is the effect of HNO2 on DNA bases?

It causes deamination Signup and view all the answers

What is the characteristic of nucleic acids that makes them reactive?

High pi bond order Signup and view all the answers

What is the result of the reaction of a carcinogen with DNA?

It leads to the formation of a DNA adduct Signup and view all the answers

What is the mechanism of initiation in carcinogenesis?

Reactivity of carcinogen with DNA Signup and view all the answers

What is the effect of endocrine disruptors on wildlife?

They cause both masculinization of females and feminization of males Signup and view all the answers

What is the effect of endocrine disruptors on human health?

They decrease male fertility Signup and view all the answers

What is the concentration gradient of Ca2+ across the plasma membrane?

10,000-fold Signup and view all the answers

Why is Ca2+ excluded from the cytosol?

Due to its larger ionic radius and ability to easily precipitate with phosphates Signup and view all the answers

What is the result of an increase in cytosolic Ca2+?

Increased binding of protein kinase C Signup and view all the answers

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

DNA Signup and view all the answers

What is the result of mitotic death?

Cell death at mitosis Signup and view all the answers

What is the function of the electron transport system?

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

What is the result of oxidative phosphorylation?

Generation of ATP Signup and view all the answers

What is the function of uncoupling proteins in brown fat?

To generate heat Signup and view all the answers

What is the result of oxidative stress?

Damage to components of the immune system Signup and view all the answers

What is the result of ROS reacting with proteins?

Oxidative modification Signup and view all the answers