Lipid Peroxidation and Cellular Defense Mechanisms

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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?

Inhibits platelet aggregation Signup and view all the answers

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

Mechanism of action Signup and view all the answers

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

Inactivation of enzymes Signup and view all the answers

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

Through covalent interaction (DNA adducts) Signup and view all the answers

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

Ultimate carcinogen Signup and view all the answers

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

To detoxify carcinogenic species Signup and view all the answers

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

Progression Signup and view all the answers

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

Continual stimulation of cell proliferation Signup and view all the answers

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

To inhibit cell growth Signup and view all the answers

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

Encode proteins that are inactive Signup and view all the answers

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

Apoptosis Signup and view all the answers

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

To explain the mechanism of chemical carcinogenesis Signup and view all the answers

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

Neoplasm Signup and view all the answers

What is the main effect of epigenetic carcinogens on DNA?

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

What type of reactants are genotoxic carcinogens typically?

Electron-deficient Signup and view all the answers

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

Formation of DNA adducts Signup and view all the answers

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

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

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

Bioactivation Signup and view all the answers

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

The final carcinogenic compound that is an electrophile Signup and view all the answers

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

Direct-acting carcinogens Signup and view all the answers

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

Gross alterations in the encoded protein Signup and view all the answers

What is the general term for a malignant neoplasm?

Cancer Signup and view all the answers

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

Ionizing radiation Signup and view all the answers

What is the result of ionizing radiation ionizing water?

Reactive oxygen species are produced that damage DNA Signup and view all the answers

What type of cells do sarcomas originate from?

Mesenchymal tissues Signup and view all the answers

What is the primary mechanism of action of epigenetic carcinogens?

Suppressing the immune system Signup and view all the answers

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

DNA-damaging agents Signup and view all the answers

What is the result of base substitutions in DNA?

Amino acid substitutions 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?

Neoplasm Signup and view all the answers

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

Aneuploidy Signup and view all the answers

What is the main difference between benign and malignant neoplasms?

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

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

It produces many tumors Signup and view all the answers

What is the primary mechanism of action of tumor promoters?

Clonal expansion of altered cells Signup and view all the answers

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

Uractil and thymines Signup and view all the answers

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

They allow for the clonal expansion of initiated cells Signup and view all the answers

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

Base substitutions Signup and view all the answers

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

(+)-Benzo[a]pyrene-7,8-diol-9,10-epoxide-2 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?

Frameshift mutations Signup and view all the answers

Which of the following is a characteristic of tumor promoters?

They are reversible in the early stages Signup and view all the answers

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

It binds covalently to DNA, forming DNA adducts Signup and view all the answers

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

An incorrect base is added to the DNA sequence Signup and view all the answers

What type of tumor promoters are phorbol esters?

Skin tumor promoters Signup and view all the answers

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

Epigenetic carcinogens Signup and view all the answers

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

Their chemical conformation/stereospecificity Signup and view all the answers

What is the bay-region theory related to?

The ultimate carcinogenic metabolites of polycyclic aromatic hydrocarbons 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?

Alkylation Signup and view all the answers

What is the most nucleophilic site in DNA?

N-7 position of guanine Signup and view all the answers

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

It affects the repair of DNA damage Signup and view all the answers

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

There is a strong correlation between the two Signup and view all the answers

What is the significance of identifying specific DNA adducts?

It can be used as a biomarker of exposure Signup and view all the answers

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

An abnormal protein product or an abnormal amount of product Signup and view all the answers

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

To control normal cellular proliferation, differentiation, and apoptosis Signup and view all the answers

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

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

What percentage of human cancers have a mutated p53 gene?

50% Signup and view all the answers

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

Missense mutations Signup and view all the answers

In what percentage of colon cancers is p53 mutated?

70% Signup and view all the answers

What is the primary function of oncogenes?

To regulate cell growth and differentiation Signup and view all the answers

How many oncogenes have been identified?

Approximately 100 Signup and view all the answers

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

Guardian of genome Signup and view all the answers

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

Apoptosis Signup and view all the answers

What is the role of Ras proteins in cellular signaling?

To function as membrane-associated molecular switches Signup and view all the answers

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

Mutations Signup and view all the answers

What happens when Ras is bound to GTP?

Ras is in the on position Signup and view all the answers

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

Both parental copies must be altered Signup and view all the answers

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

Ras is essentially stuck in the on position Signup and view all the answers

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

Mutagens Signup and view all the answers

What is the primary function of tumor suppressor genes?

To function as negative regulators of cell growth Signup and view all the answers

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

Missense mutation Signup and view all the answers

What is the effect of inactivating tumor suppressor genes?

Loss of function Signup and view all the answers

How many tumor suppressor genes have been identified?

Around 18 Signup and view all the answers

What is the result of a nonsense mutation?

A truncated protein Signup and view all the answers

What is the function of p53 protein?

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

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

Inactivation of p53 Signup and view all the answers

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?

What is a consequence of the peroxidation of membrane lipids?

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

What is a property of 4-hydroxynonenal?

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

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

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

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

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

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

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

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

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

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

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

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

What is the main effect of epigenetic carcinogens on DNA?

What type of reactants are genotoxic carcinogens typically?

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

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

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

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

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

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

What is the general term for a malignant neoplasm?

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

What is the result of ionizing radiation ionizing water?

What type of cells do sarcomas originate from?

What is the primary mechanism of action of epigenetic carcinogens?

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

What is the result of base substitutions in DNA?

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

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

What is the main difference between benign and malignant neoplasms?

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

What is the primary mechanism of action of tumor promoters?

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

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

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

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

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

Which of the following is a characteristic of tumor promoters?

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

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

What type of tumor promoters are phorbol esters?

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

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

What is the bay-region theory related to?

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

What is the most nucleophilic site in DNA?

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

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

What is the significance of identifying specific DNA adducts?

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

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

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

What percentage of human cancers have a mutated p53 gene?

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

In what percentage of colon cancers is p53 mutated?

What is the primary function of oncogenes?

How many oncogenes have been identified?

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

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

What is the role of Ras proteins in cellular signaling?

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

What happens when Ras is bound to GTP?

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

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

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

What is the primary function of tumor suppressor genes?

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

What is the effect of inactivating tumor suppressor genes?

How many tumor suppressor genes have been identified?

What is the result of a nonsense mutation?

What is the function of p53 protein?

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

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