Immunology easy
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Questions and Answers

What is a characteristic of exotoxins?

  • They are part of the bacterial cell wall.
  • They are only released during cell lysis.
  • They cause non-specific symptoms.
  • They can be regulated by the bacterium that produces them. (correct)

Which statement is true about endotoxins?

  • Endotoxins can be regulated by the bacterium.
  • Endotoxins are released only during cell lysis. (correct)
  • Endotoxins induce specific symptoms unique to each infection.
  • Endotoxins are synthesized and secreted actively by bacteria.

Which of the following describes the toxicity of lipopolysaccharides?

  • High toxicity.
  • Moderate toxicity.
  • No toxicity.
  • Low toxicity. (correct)

What role do Kupfer cells play in the action of endotoxins?

<p>They induce the production of proinflammatory cytokines. (B)</p> Signup and view all the answers

What is an example of a disease caused by exotoxins?

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

How does the body generally respond to endotoxins?

<p>By inducing fever and inflammation. (D)</p> Signup and view all the answers

From what sources do bacteria obtain the ability to synthesize exotoxins?

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

What is a common symptom caused by endotoxins?

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

What is the primary function of MHC molecules?

<p>Bind to and present peptide antigens to T cells (D)</p> Signup and view all the answers

Which genes encode MHC class I proteins?

<p>HLA-A, HLA-B, HLA-C (C)</p> Signup and view all the answers

What type of symbiosis occurs when both organisms benefit from their interaction?

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

Where are MHC class II molecules predominantly expressed?

<p>Macrophages, dendritic cells, and B cells (D)</p> Signup and view all the answers

What defines commensalism in symbiotic relationships?

<p>One benefits while the other is unaffected (C)</p> Signup and view all the answers

What is a key characteristic of obligate parasites?

<p>They can only live inside a host's cells (A)</p> Signup and view all the answers

How is MHC class II synthesized and transported within the cell?

<p>Synthesize in the ER, processed in the Golgi apparatus, and then transported to an endosome (A)</p> Signup and view all the answers

What do pattern recognition receptors (PRRs) primarily recognize?

<p>Damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs) (D)</p> Signup and view all the answers

Which of the following is an example of a hemi-parasite?

<p>None of the above (D)</p> Signup and view all the answers

What is included in the MHC class II molecule structure?

<p>Two transmembrane glycoprotein chains with a peptide-binding cleft (A)</p> Signup and view all the answers

What is the definition of an infection?

<p>An invasion and replication of a causative agent with host reaction (C)</p> Signup and view all the answers

Which types of cells are known to express Toll-like receptors (TLRs)?

<p>Macrophages, dendritic cells, neutrophils, and epithelial cells (D)</p> Signup and view all the answers

Which of these statements about T-cell receptors (TCR) is true?

<p>TCRs recognize peptide antigens only when presented by MHC molecules (A)</p> Signup and view all the answers

What is one of the main roles of the innate immune system when encountering pathogens?

<p>Detecting and ingesting microbes and damaged cells (D)</p> Signup and view all the answers

How does a facultative intracellular parasite function?

<p>It can live both inside and outside macroorganism's cells (C)</p> Signup and view all the answers

What types of antigens do MHC class II molecules primarily present?

<p>Peptide antigens of 10-20 amino acids (C)</p> Signup and view all the answers

Which component is not encoded by the MHC class III locus?

<p>MHC class I proteins (C)</p> Signup and view all the answers

Which of the following statements about Toll-like receptors (TLRs) is true?

<p>There are 10 known human TLRs, each recognizing unique microbial patterns. (C)</p> Signup and view all the answers

What is an infectious disease?

<p>A result of the infection involving both the agent and host response (D)</p> Signup and view all the answers

What initiates the activation of signal transduction pathways in the innate immune response?

<p>The binding of PRRs to DAMPs and PAMPs (C)</p> Signup and view all the answers

Which of the following is NOT a characteristic of parasitism?

<p>Both species benefit from the interaction (A)</p> Signup and view all the answers

In mutualistic relationships, what does the human host gain from E.coli?

<p>Nutrients, enzymes, and protection from pathogens (A)</p> Signup and view all the answers

Which of the following is a function of TLR2?

<p>Recognizes lipoteichoic acids of Gram-positive bacteria (B)</p> Signup and view all the answers

What role does the immune system play during an infection?

<p>It responds to the presence of infectious agents and toxins (D)</p> Signup and view all the answers

The innate immune system typically does not react against which of the following?

<p>Normal, healthy cells and tissues (B)</p> Signup and view all the answers

What are damage-associated molecular patterns (DAMPs)?

<p>Molecules released from damaged or dying cells (B)</p> Signup and view all the answers

Which type of immune response do pattern recognition receptors (PRRs) mainly promote?

<p>Non-specific resistance (B)</p> Signup and view all the answers

Which of the following correctly describes where PRRs are found?

<p>Both extracellularly and intracellularly (B)</p> Signup and view all the answers

What is the primary role of dendritic cells in the immune response?

<p>To capture and present microbial proteins to T cells (B)</p> Signup and view all the answers

Which process describes the movement of phagocytic cells towards a site of infection?

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

What enhances the binding of microbes to phagocytes?

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

What is the primary outcome of phagocytosis when it is complete?

<p>Microbes are killed and presented to T lymphocytes (D)</p> Signup and view all the answers

Which step in phagocytosis involves the engulfment of a pathogen?

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

What type of proteins are involved in the digestion of pathogens within the phagosome?

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

Which of the following is NOT a mechanism used by phagocytes to eliminate pathogens?

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

What triggers the activation of T-Lymphocytes by antigen-presenting cells?

<p>MHC class II expression (B)</p> Signup and view all the answers

What is a characteristic of phagocytosis in terms of particle size?

<p>It engulfs large particles (&gt; 0.5 um) (D)</p> Signup and view all the answers

What occurs during the binding step of phagocytosis?

<p>Microbes bind to receptors on phagocytes (B)</p> Signup and view all the answers

What are the possible outcomes for a person who gets infected?

<p>Chronic carrier state (A), Complete recovery and health (B), Exitus lethalis (death) (C)</p> Signup and view all the answers

Which type of infections appear irregularly and independently in different places?

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

What characterizes endemic infections?

<p>They are typical for specific geographic regions (A)</p> Signup and view all the answers

What defines an epidemic infection?

<p>Widespread occurrence in a society within a specific period (C)</p> Signup and view all the answers

Which of the following is an example of a pandemic infection?

<p>SARS-CoV-2 causing COVID-19 (D)</p> Signup and view all the answers

What is the first step in the infectious process?

<p>Source of infection (D)</p> Signup and view all the answers

Innate immunity refers to which aspect of immune response?

<p>Immediate and generalized defense mechanisms (C)</p> Signup and view all the answers

Which of the following is true about common signs of the infection process?

<p>They include a port of entry for the infectious agent (B)</p> Signup and view all the answers

What does immunity specifically refer to?

<p>Physiological defense reactions against foreign agents (D)</p> Signup and view all the answers

Which infection is an example of being endemic?

<p>Hepatitis E in India (C)</p> Signup and view all the answers

Flashcards

Symbiosis

The interaction between microorganisms and macroorganisms (e.g., bacteria and humans).

Mutualism

A type of symbiosis where both organisms benefit from the interaction.

Example of Mutualism

E. coli living in the human digestive tract, aiding in nutrient breakdown and protection.

Commensalism

A type of symbiosis where one organism benefits, and the other is neither harmed nor helped.

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Parasitism

A type of symbiosis where one organism benefits, and the other is harmed.

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Infection

The invasion, replication, and host reaction to a causative agent and its toxins, in human tissues.

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Infectious Disease

The resulting condition when an infection weakens the body's defenses.

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Hemi-parasite

A parasite that can exist both inside and outside a host.

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Obligate parasite

A parasite that needs a host for survival and has a very limited time outside of a host.

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Obligate intracellular parasite

A parasite that can only survive inside a host cell.

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Exotoxin

Toxic protein secreted by a bacterium.

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Endotoxin

Toxic component of the bacterial cell wall, released upon cell lysis.

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Exotoxin synthesis regulation

Bacteria can control the production and release of exotoxins.

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Endotoxin release mechanism

Released only when the bacterial cell breaks down (lysis).

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Exotoxin antigenicity

Exotoxins are highly antigenic (trigger an immune response).

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Endotoxin antigenicity

Endotoxins are weakly antigenic.

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Endotoxin mechanism of action

Endotoxins activate Kupffer cells, triggering inflammation and fever.

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Proinflammatory cytokines

Molecules (like IL-1, TNF) that induce inflammation and fever.

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Sporadic Infection

An infection that occurs randomly and independently in different locations. It's not linked to a common source or outbreak.

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Endemic Infection

An infection that is consistently present in a specific geographic region or population. It's expected and often occurs at a relatively steady rate.

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Epidemic Infection

A widespread occurrence of an infectious disease in a community or region within a specific time period. It involves a significant increase in cases beyond what is normally expected.

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Pandemic Infection

A global outbreak of an infectious disease, spreading across multiple continents or worldwide.

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Outcome of Infection

The potential result of an infection, which can be recovery, death, or becoming a carrier of the disease.

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What are the common signs of an infection process?

An infection process involves a source, the presence of a pathogen, transmission, a point of entry, stages of the disease, and an immune response.

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What is immunity?

The body's ability to resist and defend against harmful agents, particularly those with foreign genetic elements that trigger an immune response.

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Innate immunity

The body's first line of defense against infection, involving non-specific mechanisms that are always present and ready to act.

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What is the difference between Sporadic and Endemic infections?

Sporadic infections occur randomly and independently, while endemic infections are consistently present in a specific region or population.

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What stages do infections typically go through?

Most infections involve stages like incubation, prodromal, illness, decline, and convalescence, though not all stages are necessarily apparent.

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Pattern Recognition Receptors (PRRs)

Specialized receptors on immune cells that detect and bind to molecular patterns associated with pathogens (PAMPs) and damaged cells (DAMPs).

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PAMPs

Pathogen-associated molecular patterns, molecules found on microbes that are recognized by PRRs. Example: Lipoteichoic acids on Gram-positive bacteria.

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DAMPs

Damage-associated molecular patterns, molecules released from damaged or dying cells that are recognized by PRRs. Example: Heat shock proteins.

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Toll-like Receptors (TLRs)

A type of PRR that plays a crucial role in recognizing a variety of microbial products and triggering immune responses.

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TLR2

A TLR that recognizes lipoteichoic acids, a component of Gram-positive bacteria cell walls.

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TLR1 and TLR6

TLRs that recognize multiple diacyl peptides, typically found on Mycoplasma bacteria.

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TLR3, TLR7, TLR8

TLRs that recognize products of viral replication, like double-stranded RNA.

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Macrophages

Phagocytic cells that engulf and destroy pathogens and cellular debris, also expressing TLRs.

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Dendritic Cells

Cells that present antigens to T cells, triggering adaptive immune responses, also expressing TLRs.

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Neutrophils

Phagocytic cells that act as the first line of defense against invading pathogens, also expressing TLRs.

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MHC Class II

Proteins expressed on the surface of antigen-presenting cells (like macrophages and dendritic cells) that display fragments of foreign proteins (antigens) to T cells.

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Phagocytosis

A process where a phagocytic cell engulfs and destroys a pathogen.

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Chemotaxis

The movement of phagocytic cells towards a site of infection, guided by chemical signals.

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Opsonization

The process of coating a pathogen with antibodies or complement proteins, making it more easily recognized and engulfed by phagocytes.

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Phagosome

A vesicle formed within a phagocyte that encloses the engulfed pathogen.

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Phagolysosome

A vesicle formed by the fusion of a phagosome with a lysosome, where the pathogen is destroyed.

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Antimicrobial Peptides

Small proteins produced by phagocytes that kill pathogens.

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Toxic Oxygen-Derived Products

Highly reactive molecules produced by phagocytes to kill pathogens, such as superoxide, hydrogen peroxide, and singlet oxygen.

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Outcome of Phagocytosis

Phagocytosis can be complete, resulting in pathogen destruction, or incomplete, leaving pathogens inside the cell.

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MHC

A group of genes responsible for immune recognition and controlling tissue compatibility. It helps the body identify "self" from "non-self" cells.

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What do MHC Class I proteins present?

MHC Class I proteins present short peptides, typically 8-10 amino acids long, derived from intracellular proteins. These peptides can be from normal cellular proteins, viral proteins, or other pathogens.

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What do MHC Class II proteins present?

MHC Class II proteins present longer peptides, typically 13-18 amino acids long, derived from extracellular proteins. These peptides are usually from pathogens like bacteria or viruses that have been engulfed by APCs.

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Antigen Presenting Cells (APCs)

Cells specialized in capturing and processing antigens, then presenting them to T cells via MHC molecules. Examples include macrophages, dendritic cells, and B cells.

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MHC Class II molecules and peptide binding

MHC Class II molecules have a groove that can bind peptides of around 10-20 amino acids. This binding is specific and helps in antigen presentation.

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Study Notes

Types of Symbiosis

  • Mutualism - An interaction between two organisms where both benefit. An example is E. coli living in the human gut. E. coli benefits from a place to live and grow. The human benefits from E. coli breaking down nutrients and protecting against harmful invaders.

  • Commensalism - An interaction between two organisms where one benefits and the other is neither benefited nor harmed. An example is the transitory microbiota of the skin. Microorganisms gain nutrients from the skin, but the human is not affected.

  • Parasitism - An interaction between two organisms where one benefits and the other is harmed. Parasitism is often discussed in the context of infectious diseases. Parasitic organisms benefit from the interaction, while the host is harmed. Parasites can survive inside or outside the host organism. Some examples include viruses and Trichomonas vaginalis (a sexually transmitted infection).

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Description

Explore the different types of symbiotic relationships in this quiz. Learn about mutualism, commensalism, and parasitism, with examples that illustrate how these interactions affect organisms involved. Test your knowledge on how these relationships are crucial for ecosystems.

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