Molecular Biology Chapters 7 & 8 Quiz
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Questions and Answers

What is a frameshift mutation?

  • Substitution of one nucleotide for another
  • A mutation that results in a silent effect on protein function
  • Insertion or deletion of nucleotide(s) affecting the reading frame (correct)
  • Modification of a protein without altering the DNA sequence

How do spontaneous mutations occur?

  • In response to environmental factors like radiation
  • Due to mistakes during DNA replication without mutagens (correct)
  • As a result of artificial genetic manipulation
  • Through programmed cellular processes

What type of mutation typically results in a non-functional protein?

  • Nonsense mutation (correct)
  • Spontaneous mutation
  • Silent mutation
  • Missense mutation

What role do plasmids play in bacteria?

<p>They carry non-essential genes including those for antibiotic resistance (B)</p> Signup and view all the answers

What type of plasmid is responsible for carrying genes for antibiotic resistance?

<p>R plasmids (A)</p> Signup and view all the answers

Which type of mutation results in an altered amino acid sequence that may affect the function of a protein?

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

What phenomenon describes the transfer of genetic material between bacteria?

<p>Conjugation (C)</p> Signup and view all the answers

What determines whether a mutation has no effect on the protein function?

<p>The mutation must be a silent mutation (B)</p> Signup and view all the answers

Which of the following is NOT a result of induced mutations?

<p>Mistakes during DNA replication (B)</p> Signup and view all the answers

What benefit do fertility (F) plasmids provide to bacteria?

<p>Enable conjugation through F pilus formation (A)</p> Signup and view all the answers

What is the role of the RNA primer during DNA replication?

<p>It serves as a starting site for nucleotides to form a new strand. (B)</p> Signup and view all the answers

In what direction does DNA polymerase synthesize DNA?

<p>5' to 3' (D)</p> Signup and view all the answers

What are Okazaki fragments?

<p>Short segments of DNA synthesized on the lagging strand. (C)</p> Signup and view all the answers

Which enzyme is responsible for joining together Okazaki fragments?

<p>DNA ligase (D)</p> Signup and view all the answers

What happens to RNA primers after they are no longer needed in DNA replication?

<p>They are removed and replaced by DNA. (A)</p> Signup and view all the answers

What forms when a small segment of double-stranded DNA unwinds?

<p>Replication fork (C)</p> Signup and view all the answers

What is the function of DNA polymerase during DNA replication?

<p>It synthesizes new DNA strands. (C)</p> Signup and view all the answers

What is a characteristic of hepatitis B infection?

<p>Virus numbers remain high for the patient's life. (A)</p> Signup and view all the answers

Which strand is synthesized continuously during DNA replication?

<p>Leading strand (A)</p> Signup and view all the answers

What occurs during a latent viral infection?

<p>The virus integrates its DNA into the host cell's chromosome. (B)</p> Signup and view all the answers

What direction must the template strand be read for DNA synthesis to occur?

<p>3' to 5' (D)</p> Signup and view all the answers

Which virus can reactivate to cause shingles after being latent?

<p>Varicella-Zoster virus. (A)</p> Signup and view all the answers

Which type of tumor does not spread to other tissues?

<p>Benign tumor. (B)</p> Signup and view all the answers

During DNA replication, what is the relationship between the two newly formed strands?

<p>They are identical. (D)</p> Signup and view all the answers

What is the function of mucous in the mucous membranes?

<p>To trap microbes and prevent drying (A)</p> Signup and view all the answers

What is the role of proto-oncogenes in cell growth?

<p>Stimulate cell growth. (B)</p> Signup and view all the answers

What can mutations in tumor suppressor genes lead to?

<p>Uncontrolled cell growth. (B)</p> Signup and view all the answers

Which of the following is true regarding the skin's role in infection prevention?

<p>Most infections happen after the skin is broken (A)</p> Signup and view all the answers

How does saliva contribute to the body's defense against microbes?

<p>It assists in moving microbes away from the body (C)</p> Signup and view all the answers

Which of the following describes a malignant tumor?

<p>Metastasizes and invades nearby tissues. (D)</p> Signup and view all the answers

What is the primary function of lysozyme in the human body?

<p>To degrade bacterial cell walls (C)</p> Signup and view all the answers

What is a possible outcome of chronic hepatitis B infection after many years?

<p>Cirrhosis or liver cancer. (D)</p> Signup and view all the answers

What role do defensins play in the immune system?

<p>They serve as antimicrobial peptides that disrupt microbial membranes (A)</p> Signup and view all the answers

Which of the following is a characteristic of oncogenic viruses?

<p>Can lead to tumor formation. (B)</p> Signup and view all the answers

What happens to a person after the acute period of hepatitis B?

<p>The virus stays high in number for life. (D)</p> Signup and view all the answers

What is a key chemical barrier in the skin that helps prevent microbial growth?

<p>Fatty acids and lactic acid (A)</p> Signup and view all the answers

How do cilia contribute to the body's defense mechanisms?

<p>They sweep mucous away from tracts (A)</p> Signup and view all the answers

What is the primary role of lactoferrin?

<p>To bind iron and slow microbial growth (B)</p> Signup and view all the answers

What type of environment does stomach acid create to protect against microbes?

<p>Highly acidic environment that destroys many bacteria (A)</p> Signup and view all the answers

In what way do bodily fluids like tears and urine assist in fighting infections?

<p>They help move microbes away from the body (B)</p> Signup and view all the answers

What is the primary structural feature that defines each antibody's ability to bind to an antigen?

<p>The specific epitope of the antigen (A)</p> Signup and view all the answers

What are the two main regions of an antibody called?

<p>Fc region and Fab region (B)</p> Signup and view all the answers

Which of the following is a function of antibodies in the immune response?

<p>Opsonization to flag down phagocytes (C)</p> Signup and view all the answers

What protective function involves antibodies binding to and inactivating toxins and pathogens?

<p>Neutralization (D)</p> Signup and view all the answers

Which class of antibody is the most abundant in the human body and can cross the placenta?

<p>IgG (A)</p> Signup and view all the answers

Which function of antibodies promotes the destruction of infected body cells?

<p>Ab-dependent cytotoxicity (A)</p> Signup and view all the answers

How many polypeptide chains make up an antibody?

<p>Four (B)</p> Signup and view all the answers

What is the main role of the Fc region of an antibody?

<p>Activating complement proteins (C)</p> Signup and view all the answers

Which class of antibody is known to consist of five units in a pentameric structure?

<p>IgM (B)</p> Signup and view all the answers

Which of the following is NOT a function of antibodies?

<p>Producing new antibodies (C)</p> Signup and view all the answers

What is the role of dendritic cells in T cell activation?

<p>They present foreign antigens to specific T cells. (C)</p> Signup and view all the answers

Which of the following best describes cytotoxic T lymphocytes (CTLs)?

<p>They perform clonal expansion when activated. (A)</p> Signup and view all the answers

What does the term 'virulence' refer to in pathogens?

<p>The severity of disease an organism can cause. (B)</p> Signup and view all the answers

How do CTLs destroy abnormal cells?

<p>By releasing perforins and inducing apoptosis. (A)</p> Signup and view all the answers

What role does MHC class I play in the immune response?

<p>It presents endogenous antigens on cell surfaces. (C)</p> Signup and view all the answers

Which statement about pathogens is accurate?

<p>Some strains of the same species can vary in pathogenicity. (B)</p> Signup and view all the answers

What is the primary function of granzymes released by CTLs?

<p>To induce apoptosis in the target cell. (B)</p> Signup and view all the answers

Which of the following statements about infection is true?

<p>Infection is the growth of pathogens in a host. (C)</p> Signup and view all the answers

Which factor primarily influences the pathogenicity of a microbe?

<p>The virulence factors of the microbe. (B)</p> Signup and view all the answers

What triggers clonal expansion in T cells?

<p>Recognition of antigens presented by APCs. (D)</p> Signup and view all the answers

Flashcards

DNA Replication

The process of creating two identical DNA molecules from a single original DNA molecule.

Replication Fork

The point where the DNA double helix separates during replication.

Leading Strand

The strand of DNA that is synthesized continuously in the 5' to 3' direction during replication.

Lagging Strand

The strand of DNA that is synthesized discontinuously in short fragments (Okazaki fragments) during replication, then joined together.

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Okazaki Fragments

Short fragments of DNA synthesized on the lagging strand during DNA replication.

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DNA Polymerase

Enzyme that reads the template strand and adds complementary nucleotides to synthesize a new DNA strand.

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RNA Primer

Provides a starting point for DNA polymerase to add nucleotides.

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DNA Ligase

Enzyme that joins Okazaki fragments together to form a continuous strand during DNA replication.

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5' to 3' direction

The direction in which DNA polymerase synthesizes new DNA strands adding nucleotides to the 3' end.

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Primase

Enzyme responsible for synthesizing the RNA primers.

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Frameshift mutation

A mutation that changes the reading frame of mRNA, altering the amino acid sequence downstream of the mutation.

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Insertion Mutation

A frameshift mutation where one or two nucleotides are added to a gene.

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Deletion Mutation

A frameshift mutation where one or two nucleotides are removed from a gene.

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Spontaneous mutation

A mutation that occurs due to occasional mistakes during DNA replication in the absence of mutagens.

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Induced mutation

A mutation caused by DNA damaging agents called mutagens, such as radiation and some chemicals.

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Silent mutation

A mutation that has no effect on the protein's function.

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Missense mutation

A mutation resulting in a protein with a different amino acid sequence, potentially altering the protein's function.

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Nonsense mutation

A mutation that creates a premature stop codon, resulting in an incomplete and usually non-functional protein.

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Plasmid

A self-replicating, double-stranded DNA molecule that contains non-essential genes.

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F plasmid

A type of plasmid that carries genes for the F pilus, involved in bacterial conjugation.

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Latent viral infection

An infection where the virus integrates its DNA into the host cell's chromosome and remains dormant.

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Provirus

A copy of a virus's DNA integrated into a host cell's chromosome.

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Hepatitis B

A virus that can cause liver damage and potentially cancer.

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Acute infection

A period of infection with noticeable symptoms.

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Tumor

Abnormal tissue growth.

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Malignant tumor

A tumor that spreads to other tissues (cancer).

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Proto-oncogenes

Genes that stimulate cell growth.

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Tumor suppressor genes

Genes that inhibit cell growth.

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Oncogenic viruses

Viruses that can cause cancer.

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Varicella-Zoster virus

Causes chickenpox (varicella) and shingles (herpes zoster).

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Skin: First Line of Defense

The skin acts as a physical barrier, preventing microbes from entering the body. It is also slightly acidic, inhibiting microbial growth.

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Microbes and Skin

Some microbes can break down dead skin cells and oils, leading to body odor.

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Mucous Membranes: Second Line

Mucous membranes line body cavities like the digestive tract. They secrete mucous, a sticky substance that traps microbes.

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Mucocilliary Escalator

Cilia on mucous membranes sweep away trapped microbes, transporting them out of the body.

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Fluid Flow: Flushing Away

Fluids like saliva, tears, and urine wash away microbes, preventing infection.

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Stomach Acid: Chemical Defense

Stomach acid (pH 2) is highly acidic, killing many bacteria and toxins.

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Skin Acidity: Microbial Blocker

Skin is slightly acidic (pH 3-5), preventing growth of many microbes.

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Lysozyme: Enemy Decomposer

Lysozyme is an enzyme that breaks down peptidoglycan, a key component of bacterial cell walls.

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Lactoferrin: Iron Grabber

Lactoferrin binds iron, a crucial element for microbial growth, making it unavailable to microbes.

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Defensins: Antimicrobial Peptides

Defensins are small proteins that kill microbes by disrupting their cell membranes.

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Pathogen

An organism that has the ability to cause disease.

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Pathogenicity

The ability of a pathogen to cause disease.

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Virulence

The severity of a disease caused by a pathogen.

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Infection

The growth of a pathogen in the body.

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CTL

Cytotoxic T lymphocyte – a type of T cell that directly kills infected or abnormal cells.

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MHC Class I

A type of protein found on the surface of all nucleated cells that presents internal antigens to CTLs.

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Perforins

Enzymes released by CTLs that create holes in the membranes of infected or abnormal cells.

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Granzymes

Enzymes released by CTLs that trigger programmed cell death (apoptosis) in infected or abnormal cells.

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Apoptosis

Programmed cell death – a controlled and organized process of cell self-destruction.

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Endogenous Antigen

An antigen that is produced inside a cell, such as a viral protein.

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Epitope

The specific part of an antigen that an antibody binds to. It's like a unique key slot on a protein's surface.

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Antibody Structure

An antibody is made of four polypeptide chains - two light chains and two heavy chains. It has two Fab regions (arms) for binding antigens and one Fc region (stem) for interacting with other immune cells.

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Fab Region

The 'arms' of an antibody that contain the antigen binding site. Each Fab region binds to one specific epitope on an antigen.

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Fc Region

The 'stem' of an antibody that interacts with other immune cells and proteins to activate immune responses. It's the 'signal beacon' for other immune cells.

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Cross-linking (Agglutination)

The process where antibodies bind to multiple antigens, clumping them together. This reduces the number of infectious units that need to be dealt with.

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Neutralization

Antibodies bind to and inactivate toxins, bacteria, or viruses. It's like blocking a virus's keyhole, preventing it from entering a cell.

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Complement Activation

Antibodies activate the complement system, a cascade of proteins that helps destroy pathogens by creating pores (MAC attack) on their membranes.

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Opsonization

Antibodies coat pathogens, making it easier for phagocytic cells to engulf and destroy them. It's like putting a 'flag' on a pathogen, signaling for its removal.

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Antibody-Dependent Cell Cytotoxicity (ADCC)

Antibodies attach to infected or abnormal cells, signaling for natural killer (NK) cells to destroy them. It's like giving a target to a NK cell to destroy the bad cell.

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Immobilization and Prevention of Adherence

Antibodies bind to flagella or pili, preventing bacteria from moving or colonizing. It's like putting brakes on a bacterial car or locking the door to a cell.

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Study Notes

Chapter 7 & 8: The Blueprint of Life & Bacterial Genetics

  • Central Dogma of Molecular Biology describes the flow of genetic information
  • Genetics is the science of heredity
  • Molecular Biology studies DNA and protein synthesis.
  • Genome is the total DNA in a cell, consisting of chromosomes and plasmids
  • Chromosomes contain genes, which are sections of DNA coding for functional products.
  • DNA is a macromolecule made of nucleotides, which have a nitrogenous base, a sugar (deoxyribose), and a phosphate
  • DNA strands are held together by hydrogen bonds
  • Base pairing rule: A with T, G with C
  • DNA strands run antiparallel (5' to 3')
  • DNA replication involves using one strand as a template to create a complementary strand
  • DNA polymerase synthesizes DNA in the 5' to 3' direction, while reading the template in the 3' to 5' direction

Chapter 7: Gene Expression/Transcription & Translation

  • Gene expression involves two processes: transcription and translation
  • Transcription: The process of copying the information encoded in DNA into RNA (DNA -> RNA)
  • Translation: The process of using the information in RNA to produce a protein (RNA -> Protein).
  • mRNA carries the information for protein synthesis
  • rRNA forms part of the ribosome
  • tRNA transports amino acids for protein synthesis
  • mRNA reads the process of amino-acid synthesis
  • DNA templates are read from the 3' to 5' direction for RNA syntheses that occur from the 5' to 3' direction.

Chapter 8: Microbial Genetics

  • Genetic change in bacteria can occur via mutation or horizontal gene transfer.
  • Mutation: A change in the DNA nucleotide sequence.
  • Horizontal gene transfer(HGT): Movement of genetic material between cells.
  • Mutations can occur spontaneously or be induced.
  • Spontaneous mutations occur during DNA replication (mistakes in DNA sequence).
  • Induced mutations are caused by mutagens (substances that damage DNA or its replication processes).
  • Mutations may have no effect on the protein, or cause a change in protein function.

Chapter 13: Viruses, Viroids and Prions

  • Viruses are acellular particles, which are not free-living.
  • Nucleic acid – either DNA or RNA
  • Capsid – a protein coat
  • Envelope (some viruses have this) – External lipid bilayer
  • Host range – species of organism that the virus can infect.
  • Virus Size: microscopic range from 20 to 1000 nm
  • Viral architecture: Consist of a Nucleic acid (DNA or RNA), capsid & an Envelope (in some cases).
  • Replication of viruses occurs within an infected host cell.

Chapter 14: Innate Immune Response

  • Innate immunity provides the first line of defense against microbes and other harmful substances.
  • Physical barriers: skin and mucous membranes.
  • Chemical defenses: enzymes, acids, and antimicrobial substances.
  • Fluid flow: saliva, tears, urine, etc., washes microbes away.

Chapter 15: Adaptive Immune Response

  • Adaptive immunity is a slower response to microbes than that of the innate immune response, but is more specific and adaptable.
  • Involves two types of immune responses: cell-mediated (T cells) and humoral (B cells).
  • Immunologic memory occurs for faster response on re-exposure to the same antigen.

Chapter 16: Host-Microbe Interactions

  • Pathogens: Microorganisms that cause diseases.
  • Mechanisms of pathogenesis: the steps pathogens take to cause disease.
  • The factors that determine success and virulence of pathogens

Chapter 17: Applications of Immune Responses

  • Vaccine – preparation of microbes, their parts, toxins, or inactivated viruses, to induce an immune response without causing infectious complications
  • Different types of vaccines exist, including attenuated whole-agent vaccines, inactivated whole-agent vaccines, toxoids, subunit vaccines, and conjugated vaccines.
  • Some common diseases are prevented by following preventative measures like vaccinations.

Chapter 18: Immunologic Disorders

  • Hypersensitivity is an exaggerated immune response to an antigen.
  • There are four types of hypersensitivity reactions, based on the immune mechanism involved.
  • Immunodeficiency disorders relate immunity issues. Immunodeficiency is a failure of the immune system to respond adequately to infection. There are two types, primary and acquired.

Chapter 19: Epidemiology

  • Epidemiology is the study of how diseases spread and affect populations.
  • Epidemiology aims to understand the factors that influence the occurrence of diseases.
  • Important terms in epidemiology include pathogen, pathogenicity, virulence, infection, and disease.
  • There are three main routes of transmission of diseases: contact, vehicle, and vector.

Chapter 17: Healthcare-Associated Infections (HAIs)

  • Healthcare-associated infections (HAIs), also known as nosocomial infections, are infections acquired in a healthcare setting (hospital, clinic, etc).
  • HAIs result from several factors, including pathogenic organisms present in the healthcare environment and compromised immune systems of patients.
  • Preventing HAIs requires stringent measures like sanitation, hygiene, and proper environmental controls.

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Test your knowledge on the Central Dogma of Molecular Biology, gene expression, and bacterial genetics. Delve into the details of DNA structure, replication, and the significance of chromosomes and genes in heredity. This quiz is essential for anyone studying molecular biology and genetics.

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