Lipid Peroxidation and Cellular Defense Mechanisms
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Questions and Answers

What is the result of antioxidants donating a hydrogen atom to the lipid peroxy radical species?

  • Release of material from subcellular compartments
  • Loss of polyunsaturated fatty acids
  • Formation of lipid radical and lipid hydroperoxide
  • Formation of nonradical products (correct)

    • What is a consequence of the peroxidation of membrane lipids?

  • Decreased lipid fluidity (correct)
  • Increased lipid fluidity
  • Unchanged ion transport
  • Increased membrane permeability

    • What is a type of product formed during lipid peroxidation reactions?

  • Alkanals
  • Alkanes
  • Alkenals
  • All of the above (correct)

    • What is a property of 4-hydroxynonenal?

    <p>Inhibits platelet aggregation</p> Signup and view all the answers

    What is the basis for subdividing carcinogens into two main types?

    <p>Mechanism of action</p> Signup and view all the answers

    What is the result of Schiff base formation with amino groups?

    <p>Inactivation of enzymes</p> Signup and view all the answers

    What is the main mechanism by which chemical carcinogens alter DNA?

    <p>Through covalent interaction (DNA adducts)</p> Signup and view all the answers

    What is the term for the actual metabolite that covalently binds to the DNA?

    <p>Ultimate carcinogen</p> Signup and view all the answers

    What is the purpose of phase I and phase II enzymes in the cell?

    <p>To detoxify carcinogenic species</p> Signup and view all the answers

    What is the term for the process by which a benign tumor becomes a malignant tumor?

    <p>Progression</p> Signup and view all the answers

    What is the result of a gain-of-function mutation in a proto-oncogene?

    <p>Continual stimulation of cell proliferation</p> Signup and view all the answers

    What is the function of tumor suppressor genes and the proteins they encode?

    <p>To inhibit cell growth</p> Signup and view all the answers

    What is the result of a loss-of-function mutation in a tumor suppressor gene?

    <p>Encode proteins that are inactive</p> Signup and view all the answers

    What is the term for the process by which a cell undergoes programmed cell death?

    <p>Apoptosis</p> Signup and view all the answers

    What is the purpose of the electrophilic theory of chemical carcinogenesis?

    <p>To explain the mechanism of chemical carcinogenesis</p> Signup and view all the answers

    What is the term for a tissue swelling, which is technically defined as a tumor?

    <p>Neoplasm</p> Signup and view all the answers

    What is the main effect of epigenetic carcinogens on DNA?

    <p>They exert their cancer-forming effect by means other than direct interaction with DNA</p> Signup and view all the answers

    What type of reactants are genotoxic carcinogens typically?

    <p>Electron-deficient</p> Signup and view all the answers

    What is the result of electrophilic genotoxic carcinogens reacting with DNA?

    <p>Formation of DNA adducts</p> Signup and view all the answers

    What is the difference between activation-dependent and activation-independent carcinogens?

    <p>Activation-dependent carcinogens require biotransformation, while activation-independent do not</p> Signup and view all the answers

    What is the process by which non-carcinogenic compounds are converted into carcinogenic compounds?

    <p>Bioactivation</p> Signup and view all the answers

    What is the ultimate carcinogen in the activation-dependent process?

    <p>The final carcinogenic compound that is an electrophile</p> Signup and view all the answers

    What type of carcinogens do not require metabolic activation to interact with DNA?

    <p>Direct-acting carcinogens</p> Signup and view all the answers

    What is the result of frame shift mutations in the encoded protein?

    <p>Gross alterations in the encoded protein</p> Signup and view all the answers

    What is the general term for a malignant neoplasm?

    <p>Cancer</p> Signup and view all the answers

    What type of radiation is responsible for DNA damage through direct ionization of DNA?

    <p>Ionizing radiation</p> Signup and view all the answers

    What is the result of ionizing radiation ionizing water?

    <p>Reactive oxygen species are produced that damage DNA</p> Signup and view all the answers

    What type of cells do sarcomas originate from?

    <p>Mesenchymal tissues</p> Signup and view all the answers

    What is the primary mechanism of action of epigenetic carcinogens?

    <p>Suppressing the immune system</p> Signup and view all the answers

    What type of agents are inorganic DNA-damaging agents, such as arsenic, chromium, and nickel?

    <p>DNA-damaging agents</p> Signup and view all the answers

    What is the result of base substitutions in DNA?

    <p>Amino acid substitutions</p> Signup and view all the answers

    What is the term for the process of abnormal cell growth that exceeds and is uncoordinated with normal tissue?

    <p>Neoplasm</p> Signup and view all the answers

    What is the term for the gain or loss of one or more chromosomes?

    <p>Aneuploidy</p> Signup and view all the answers

    What is the main difference between benign and malignant neoplasms?

    <p>Benign neoplasms do not invade surrounding tissue, while malignant neoplasms do</p> Signup and view all the answers

    In the initiation-promotion model, what is the effect of chronic treatment with a tumor promoter?

    <p>It produces many tumors</p> Signup and view all the answers

    What is the primary mechanism of action of tumor promoters?

    <p>Clonal expansion of altered cells</p> Signup and view all the answers

    What is the result of deamination of cytosines and S-methylcytosines?

    <p>Uractil and thymines</p> Signup and view all the answers

    What is the role of tumor promoters in the carcinogenic process?

    <p>They allow for the clonal expansion of initiated cells</p> Signup and view all the answers

    What is the term for the replacement of the correct nucleotide by an incorrect one?

    <p>Base substitutions</p> Signup and view all the answers

    What is the ultimate carcinogen formed from benzo[a]pyrene?

    <p>(+)-Benzo[a]pyrene-7,8-diol-9,10-epoxide-2</p> Signup and view all the answers

    What is the term for the addition or deletion of one or a few base pairs in protein coding regions?

    <p>Frameshift mutations</p> Signup and view all the answers

    Which of the following is a characteristic of tumor promoters?

    <p>They are reversible in the early stages</p> Signup and view all the answers

    What is the effect of (+)-benzo[a]pyrene-7,8-diol-9,10-epoxide-2 on DNA?

    <p>It binds covalently to DNA, forming DNA adducts</p> Signup and view all the answers

    What is the result of DNA replication itself being error-prone?

    <p>An incorrect base is added to the DNA sequence</p> Signup and view all the answers

    What type of tumor promoters are phorbol esters?

    <p>Skin tumor promoters</p> Signup and view all the answers

    What is the term for the classification of carcinogens that are not classified as direct carcinogens?

    <p>Epigenetic carcinogens</p> Signup and view all the answers

    What is important for the carcinogenic activity of polycyclic aromatic hydrocarbons besides their chemical configuration?

    <p>Their chemical conformation/stereospecificity</p> Signup and view all the answers

    What is the bay-region theory related to?

    <p>The ultimate carcinogenic metabolites of polycyclic aromatic hydrocarbons</p> Signup and view all the answers

    What type of damage can be caused to DNA by carcinogens such as N-methyl-N-nitro-N-nitrosoguanidine and methyl methanesulfonate?

    <p>Alkylation</p> Signup and view all the answers

    What is the most nucleophilic site in DNA?

    <p>N-7 position of guanine</p> Signup and view all the answers

    What is the significance of the retention time of DNA adducts in DNA?

    <p>It affects the repair of DNA damage</p> Signup and view all the answers

    What is the correlation between the formation of specific DNA adducts and tumorigenicity?

    <p>There is a strong correlation between the two</p> Signup and view all the answers

    What is the significance of identifying specific DNA adducts?

    <p>It can be used as a biomarker of exposure</p> Signup and view all the answers

    What is the result of the mutational activation of proto-oncogenes?

    <p>An abnormal protein product or an abnormal amount of product</p> Signup and view all the answers

    What is the function of the protein products of proto-oncogenes?

    <p>To control normal cellular proliferation, differentiation, and apoptosis</p> Signup and view all the answers

    What is the result of chemical mutagens and carcinogens on mammalian cells?

    <p>They produce point mutations, frameshift mutations, strand breaks, and chromosome aberrations</p> Signup and view all the answers

    What percentage of human cancers have a mutated p53 gene?

    <p>50%</p> Signup and view all the answers

    What is the most common type of p53 mutation in human cancer?

    <p>Missense mutations</p> Signup and view all the answers

    In what percentage of colon cancers is p53 mutated?

    <p>70%</p> Signup and view all the answers

    What is the primary function of oncogenes?

    <p>To regulate cell growth and differentiation</p> Signup and view all the answers

    How many oncogenes have been identified?

    <p>Approximately 100</p> Signup and view all the answers

    What is the term used to describe p53's function in maintaining genomic stability?

    <p>Guardian of genome</p> Signup and view all the answers

    What is the consequence of a severe DNA damage on a cell with a mutated p53?

    <p>Apoptosis</p> Signup and view all the answers

    What is the role of Ras proteins in cellular signaling?

    <p>To function as membrane-associated molecular switches</p> Signup and view all the answers

    What is the term used to describe the changes in the primary sequence of DNA?

    <p>Mutations</p> Signup and view all the answers

    What happens when Ras is bound to GTP?

    <p>Ras is in the on position</p> Signup and view all the answers

    What is the result of a mutation in a recessive gene?

    <p>Both parental copies must be altered</p> Signup and view all the answers

    What is the result of a mutation in the 12th or 61st codon of Ras?

    <p>Ras is essentially stuck in the on position</p> Signup and view all the answers

    What is the term used to describe chemical and physical agents that can produce a mutation?

    <p>Mutagens</p> Signup and view all the answers

    What is the primary function of tumor suppressor genes?

    <p>To function as negative regulators of cell growth</p> Signup and view all the answers

    What is the consequence of a point mutation involving a single base pair substitution?

    <p>Missense mutation</p> Signup and view all the answers

    What is the effect of inactivating tumor suppressor genes?

    <p>Loss of function</p> Signup and view all the answers

    How many tumor suppressor genes have been identified?

    <p>Around 18</p> Signup and view all the answers

    What is the result of a nonsense mutation?

    <p>A truncated protein</p> Signup and view all the answers

    What is the function of p53 protein?

    <p>To participate in many cellular functions, including cell cycle regulation, DNA repair, and apoptosis</p> Signup and view all the answers

    What is the effect of a single point mutation in the p53 protein?

    <p>Inactivation of p53</p> Signup and view all the answers

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