Immunology Chapter Quiz

Questions and Answers

Where are neutrophils primarily found in the body?

Only within lymph nodes

In the lymphatic system only

In blood and tissue fluid (correct)

In bone marrow only

What is the primary development site for macrophages?

Mucous membranes

Bone marrow

Blood

Lymph nodes (correct)

Which molecules are identified as opsonins in the phagocytosis process?

Only complement proteins

Pathogen Associated Molecular Patterns (PAMPs)

Antibodies, complement proteins, and other small circulating proteins (correct)

Only antibodies

What step follows the detection of a pathogen by a phagocyte?

The phagocyte is activated Signup and view all the answers

Which type of immune response are macrophages primarily involved in?

Adaptive, specific immune response Signup and view all the answers

What function does interferons serve during phagocyte activation?

They help activate the phagocyte Signup and view all the answers

What characteristic differentiates neutrophils from macrophages?

Neutrophils are short-acting while macrophages are longer-lasting Signup and view all the answers

What term describes the process by which phagocytes engulf pathogens?

Phagocytosis Signup and view all the answers

What is the primary role of macrophages in the immune response?

They activate T cells by presenting antigens. Signup and view all the answers

Which statement correctly describes the role of saponins in plant defense?

They destroy fungi cell membranes. Signup and view all the answers

What occurs during the process of clonal deletion?

Self-reactive immune cells are killed off. Signup and view all the answers

What initiates the activation of T-helper (TH) cells?

Antigen presentation by APCs. Signup and view all the answers

What type of immunity do memory T cells provide?

Long-term immunity to future infections. Signup and view all the answers

Which cytokines are primarily produced by T-helper cells?

Cytokines that enhance B cell and T cell proliferation. Signup and view all the answers

What are perforins crucial for in the action of cytotoxic T cells?

Creating pores in the infected cell membrane. Signup and view all the answers

Which type of antigen presenting cell (APC) has the least role in antigen presentation?

Neutrophils. Signup and view all the answers

What is the mechanism through which granzyme B destroys a target cell?

It activates apoptosis directly. Signup and view all the answers

What is the main function of regulatory T cells (TR)?

To inhibit the activity of other immune cells. Signup and view all the answers

How do plants prevent the spread of pathogens between cells?

By accumulating callose at plasmodesmata. Signup and view all the answers

What is the significance of central tolerance during lymphocyte maturation?

Helps eliminate self-reactive lymphocytes. Signup and view all the answers

What role do phytoalexins play in plant defense mechanisms?

They inhibit growth of pathogens. Signup and view all the answers

What occurs to T cells after they exit the thymus?

They disperse throughout the lymphatic system and tissues. Signup and view all the answers

What is a primary goal of personalised medicines based on DNA?

To customize treatments for optimum effectiveness Signup and view all the answers

How is synthetic biology applied in medicine?

By redesigning organisms for therapeutic purposes Signup and view all the answers

What potential benefit does preventing deforestation have on medicine discovery?

It allows for the discovery of new medicinal compounds Signup and view all the answers

Which of the following is NOT a feature of synthetic biology?

Using traditional breeding methods for medicine Signup and view all the answers

What is the significance of creating T cell receptors that bind specifically to cancer antigens?

To improve the accuracy of targeting cancer cells Signup and view all the answers

What is the primary role of plasma B cells during an infection?

To produce antibodies specific to the pathogen Signup and view all the answers

Which statement correctly describes the role of interferons in viral infections?

They inhibit viral replication and enhance defense mechanisms Signup and view all the answers

What triggers the differentiation of B cells into either plasma cells or memory B cells?

The process known as clonal expansion Signup and view all the answers

How do antibodies prevent viruses from infecting host cells?

By binding to and neutralizing viral attachment proteins Signup and view all the answers

What characteristic distinguishes monoclonal antibodies from polyclonal antibodies?

Monoclonal antibodies have a highly specific antigen binding site Signup and view all the answers

What is meant by 'humoral immunity'?

Immunity facilitated by antibodies and other macromolecules in body fluids Signup and view all the answers

What role does the variable region of an antibody play?

It provides a unique binding site specific to each antigen Signup and view all the answers

Which statement aptly describes agglutination as a function of antibodies?

Antibodies bind to multiple pathogens, clumping them together Signup and view all the answers

What is the significance of memory B cells in the immune response?

They provide a quicker, more effective response upon reinfection Signup and view all the answers

What role do lysozymes play in phagocytosis?

They hydrolyse the engulfed pathogen. Signup and view all the answers

What is the main mechanism by which antibodies neutralize pathogens?

They bind to and inactivate toxins and attachment proteins Signup and view all the answers

Which of these functions of antibodies involves marking pathogens for destruction?

Opsination Signup and view all the answers

How do phagocytes locate pathogens within the body?

Through chemotaxis driven by released chemicals and antibodies. Signup and view all the answers

How do enzymes interact with antibodies in the immune response?

They catalyze reactions that break down pathogens bound to antibodies Signup and view all the answers

What is the primary function of the skin as a primary defense?

To form a barrier against pathogen entry. Signup and view all the answers

Which of the following describes the process of inflammation?

A biological response involving swelling, redness, and pain. Signup and view all the answers

What do TH cells specifically do in relation to B cells?

They activate pathogen-specific B cells Signup and view all the answers

What is the relationship between clonal expansion and the immune response?

Clonal expansion enables rapid proliferation of specific B cells Signup and view all the answers

What is the function of goblet cells in mucous membranes?

To secrete mucous that traps pathogens. Signup and view all the answers

What is the primary purpose of exocytosis in phagocytes?

To discard waste products from digestion. Signup and view all the answers

Which component of the skin assists in strengthening its barrier function?

Keratin Signup and view all the answers

How do platelets contribute to wound repair?

By forming a mesh that plugs the wound. Signup and view all the answers

What role does the waxy cuticle play in plant defenses?

It serves as a barrier to pathogen entry. Signup and view all the answers

What process allows the gut to protect against pathogens?

Acidic conditions destroying ingested pathogens. Signup and view all the answers

What is the role of MHC class II molecules in the immune response?

They present antigens to activate T-helper cells. Signup and view all the answers

What happens during the process of chemotaxis?

Phagocytes move toward a chemical signaled by pathogens. Signup and view all the answers

Which step follows the fusion of the phagosome with a lysosome?

Digestive products are absorbed by the phagocyte. Signup and view all the answers

In response to tissue damage, what is the primary effect of vasodilation?

Increase in the permeability of blood vessels. Signup and view all the answers

What is the primary role of monoclonal antibodies in pregnancy testing?

To detect the presence of human chorionic gonadotrophin (hCG) Signup and view all the answers

Which step is NOT part of the hybridoma method for producing monoclonal antibodies?

Harvesting antibodies directly from blood Signup and view all the answers

What key benefit does natural immunity provide after the first infection?

Development of immunological memory through memory cells Signup and view all the answers

How do vaccines contribute to artificial immunity?

They stimulate the immune system to create its own memory Signup and view all the answers

What is a common characteristic of active immunity?

It develops when the body produces its own antibodies Signup and view all the answers

Which statement best describes passive immunity?

It is acquired through the injection of antibodies from another organism Signup and view all the answers

Why is vaccination particularly important in the context of herd immunity?

It protects those who cannot be vaccinated by breaking the pathogen's chain of infection Signup and view all the answers

What typically happens to immunological memory over time after vaccination?

It fades, necessitating booster vaccinations for some vaccines Signup and view all the answers

Which of the following correctly describes the process of natural immunity transfer to infants?

It is limited to antibody transfer through breast milk Signup and view all the answers

What limitation is currently noted regarding vaccines?

Vaccines can only be designed for viruses, not bacteria Signup and view all the answers

Which factor is a critical reason for the need for vaccines against many pathogens?

Natural immunity takes too long against rapid infections Signup and view all the answers

Which aspect of herd immunity is critical for protecting unvaccinated individuals?

High vaccination rates in the population lower pathogen transmission Signup and view all the answers

What is the consequence if the majority of a population is not vaccinated?

Unvaccinated individuals are more vulnerable to outbreaks Signup and view all the answers

What primarily causes the loss of herd immunity in a population?

Individuals not receiving vaccines Signup and view all the answers

What is a significant consequence of declining vaccination rates in a population?

Return of near-eradicated diseases Signup and view all the answers

What challenge does antigenic variability present to vaccination?

Pathogens may change and evade immune memory Signup and view all the answers

How does antigenic shift differ from antigenic drift?

Drift is gradual, while shift is sudden and significant. Signup and view all the answers

Why do new influenza vaccines need to be developed annually?

The influenza virus evolves quickly with new strains. Signup and view all the answers

What characteristic of tuberculosis bacteria aids in its survival within the host?

Waxy, thick cell wall Signup and view all the answers

Which feature of HIV complicates the body’s immune response?

HIV primarily targets helper T cells. Signup and view all the answers

What type of antibiotic action prevents bacteria from growing and replicating?

Bacteriostatic Signup and view all the answers

What is primarily found in the outer membrane of gram-negative bacteria?

Endotoxins Signup and view all the answers

What consequence results from unvaccinated individuals contracting influenza?

More chances for the virus to evolve Signup and view all the answers

Why can HIV remain dormant in the body for years?

It integrates into the host DNA. Signup and view all the answers

What is an important factor to consider when responding to outbreaks of diseases related to herd immunity?

Declining vaccination rates can lead to disease outbreaks. Signup and view all the answers

What is a hallmark of antigenic drift in viruses?

Gradual accumulation of mutations in antigens. Signup and view all the answers

What is a potential risk associated with using antibiotics against infections?

They may disrupt the balance of gut microbiota. Signup and view all the answers

What primarily leads to the reactivation of dormant tuberculosis in a host?

Weakened immune systems Signup and view all the answers

What is the primary action of bacteriostatic antibiotics?

They prevent bacteria from growing or reproducing. Signup and view all the answers

Which of the following is a true statement regarding bactericidal antibiotics?

They cause irreversible damage to bacterial cell walls. Signup and view all the answers

How does antibiotic resistance predominantly develop in bacteria?

Due to genetic mutations that provide a survival advantage. Signup and view all the answers

Which antibiotic-resistant bacteria is known to cause gastrointestinal infections?

Clostridium difficile Signup and view all the answers

What is a primary concern regarding antibiotic resistance in healthcare?

It complicates the treatment of infections, making them life-threatening. Signup and view all the answers

What is a recommended practice for healthcare staff when treating patients with antibiotic-resistant infections?

To isolate them in separate rooms and use protective equipment. Signup and view all the answers

What is the significance of the Bare Below the Elbow policy in healthcare settings?

It reduces the risk of infection transmission. Signup and view all the answers

In an antibiotic sensitivity assay using agar plates, what is measured to determine the effectiveness of the antibiotics?

The radius of the clearing zone around the antibiotic discs. Signup and view all the answers

Which of the following compounds is used in the production of aspirin?

Natural compound from willow bark. Signup and view all the answers

What technique is crucial to avoid contamination while conducting antibiotic tests?

Maintaining strict aseptic techniques. Signup and view all the answers

What should be done after placing antibiotic discs on the agar plate?

Seal the agar plate with tape and incubate it. Signup and view all the answers

Which of the following best represents a possible consequence of widespread antibiotic use?

The emergence of antibiotic-resistant strains. Signup and view all the answers

Why is biodiversity important for the development of new medicines?

It increases the likelihood of discovering natural compounds with medicinal properties. Signup and view all the answers

What is the most effective strategy for cholera prevention in communities?

Provision of clean drinking water Signup and view all the answers

Which factor is most likely to contribute to the spread of diseases in populated areas?

Unsanitary living conditions and dense population Signup and view all the answers

What public health strategy can assist in the prevention of malaria?

Destroying mosquito habitats by improving sanitation Signup and view all the answers

Which of the following is an essential preventative measure for managing tuberculosis (TB)?

Ensuring access to TB vaccines and treatments Signup and view all the answers

What key strategy is emphasized for reducing the transmission of HIV?

Public education on safe sex and avoiding needle sharing Signup and view all the answers

Which of the following pathogens causes athlete’s foot?

Fungi Signup and view all the answers

Which disease is transmitted through droplet transmission?

Influenza Signup and view all the answers

What type of organism is responsible for malaria?

Protoctist Signup and view all the answers

Which of the following diseases is not caused by a pathogen that infects animals?

Black sigatoka Signup and view all the answers

What defines indirect transmission of infectious diseases?

Pathogens transmitted via an intermediary source Signup and view all the answers

Which disease is not caused by viruses?

Bacterial meningitis Signup and view all the answers

Which of the following hosts can be affected by cholera?

Humans only Signup and view all the answers

What type of organisms are categorized as pathogens that can infect plants?

Fungi, bacteria, and viruses Signup and view all the answers

What mode of transmission is responsible for cholera infections?

Contact with contaminated water and food Signup and view all the answers

Which of the following statements correctly describes malaria transmission?

It is primarily transmitted by female mosquitoes that inject parasites into the bloodstream. Signup and view all the answers

What is the main function of spores produced by Puccinia graminis in stem rust infections?

To facilitate asexual reproduction and spread to other plants Signup and view all the answers

Which of the following is a characteristic of tuberculosis?

It is an airborne disease spread by respiratory droplets. Signup and view all the answers

What characterizes the life cycle of the malaria parasite?

It requires both a mosquito and human for full development. Signup and view all the answers

What type of fluid is primarily responsible for the transmission of HIV?

Blood and other body fluids Signup and view all the answers

Which group of pathogens is chiefly responsible for malaria?

Parasites Signup and view all the answers

What defines stem rust as a significant disease in agriculture?

It primarily targets wheat and barley crops. Signup and view all the answers

What is a common symptom of cholera that signifies infection?

Profuse watery diarrhea Signup and view all the answers

What is the role of vectors in the transmission of diseases like malaria?

They transport pathogens directly in their saliva during feeding. Signup and view all the answers

How does HIV transmission occur through vertical transmission?

From an infected mother to her child during pregnancy Signup and view all the answers

Which of the following is NOT a factor in the endemic nature of malaria?

Cold weather conditions Signup and view all the answers

What factor increases the risk of tuberculosis infection among individuals?

Close or prolonged contact with infected individuals Signup and view all the answers

What is a key symptom of the advanced stage of HIV leading to AIDS?

Severe depletion of immune cells Signup and view all the answers

Which step of the viral life cycle allows a virus to bind specifically to a host cell?

Virus binds to host cells Signup and view all the answers

What is the primary significance of hepatitis virus's ability to inject nucleic acids into host cells?

It hijacks the host cell's machinery for virus replication. Signup and view all the answers

What occurs during the lytic release phase of a viral life cycle?

Viruses break free from the host cell via bursting. Signup and view all the answers

How do viruses influence the energy usage of the host cell after injecting their components?

They redirect the host cell's energy to replicate viral components. Signup and view all the answers

In which phase does a virus utilize its attachment proteins to establish an infection?

Virus binds to host cells Signup and view all the answers

What is the ultimate consequence for the host cell after the viral replication process is complete?

The host cell eventually dies. Signup and view all the answers

Which of the following correctly describes a role of viral proteins once injected into a host cell?

They help the virus evade immune detection. Signup and view all the answers

What determines the type of host cells a virus can infect?

The presence of specific attachment proteins. Signup and view all the answers

What mechanism allows a virus to replicate within a host cell?

The virus injects its nucleic acids and hijacks the cell's machinery. Signup and view all the answers

Which type of viral genome can be injected into a host cell?

Both DNA and RNA genomes can be injected. Signup and view all the answers

What is the primary result of the lytic release in the viral life cycle?

The host cell dies, releasing new viral particles. Signup and view all the answers

How do attachment proteins influence the infection process of viruses?

They determine the type of host cells that viruses can bind to. Signup and view all the answers

What happens to the cellular machinery during viral replication?

The cellular machinery focuses on producing viral components instead of its own. Signup and view all the answers

Which statement accurately describes the function of a virus's capsid?

It facilitates the binding of the virus to host cells. Signup and view all the answers

Which of the following is a characteristic of all viruses?

They contain no ribosomes. Signup and view all the answers

What type of genome does the Ebola virus possess?

Single stranded DNA Signup and view all the answers

Which of the following statements is true regarding viruses and their size?

Viruses are smaller than the smallest prokaryotes. Signup and view all the answers

How do viruses typically reproduce inside host cells?

They hijack the host's cellular machinery. Signup and view all the answers

What is the primary component of a virus that determines its classification?

The structure and type of its capsid and genome. Signup and view all the answers

Which component aids viruses in interacting with and infecting host cells?

Capsid proteins Signup and view all the answers

In which of the following environments are viruses most likely to be found?

Inside a host cell, where they replicate. Signup and view all the answers

What characteristic distinguishes viruses from living organisms?

Viruses do not possess cellular organelles. Signup and view all the answers

Which of the following accurately describes the function of a viral capsid?

It protects the viral genome from environmental damage. Signup and view all the answers

What type of genome does the Ebola virus possess?

Single stranded DNA Signup and view all the answers

How do viruses primarily gain entry into host cells?

Through attachment proteins Signup and view all the answers

Which statement is NOT true about viruses?

Viruses have both RNA and DNA in their structure. Signup and view all the answers

What is the primary reason why viruses are classified based on their capsid structure?

Capsid structure influences the immune response generated against the virus. Signup and view all the answers

Which type of virus structure does the Lambda phage virus exhibit?

Prolate structure Signup and view all the answers

Which component is NOT part of a virus's basic structure?

Ribosomes Signup and view all the answers

What role do attachment proteins play in viral infections?

They enable virus to bind to host cells. Signup and view all the answers

Which virus primarily infects e.coli?

Lambda phage virus Signup and view all the answers

Study Notes

Innate Immune Cells

Innate immune cells are widely distributed throughout the body, including mucous membranes and tissues, and travel via the lymphatic system.
Neutrophils: Common phagocytes found in blood and tissue fluid, produced in bone marrow, and engage in immediate, short-term responses.
Macrophages: Larger than neutrophils, develop in lymph nodes, involved in both innate and adaptive immune responses.

Phagocytosis Process

Phagocytosis involves the engulfing of pathogens by cells, characterized by the detection of pathogens through Pathogen Associated Molecular Patterns (PAMPs) and Pathogen Recognition Receptors (PRRs).
Activation of phagocytes is enhanced by signaling molecules like interferons.
Pathogens may be coated with opsonins (e.g., antibodies, complement proteins) for easier recognition by phagocytes.
Pathogens are engulfed into vesicles called phagosomes, where they are broken down within lysosomes releasing enzymes called lysozymes.
The phagocyte absorbs hydrolysis products and can present some on MHC class II molecules to stimulate T-helper cells.

Finding Pathogens

Chemotaxis: Both antibodies and chemicals released by pathogens help attract phagocytes to infection sites.

Primary Defences

Primary defences are non-specific barriers to prevent pathogen entry, including:
- Skin: A physical barrier enriched with keratin and antimicrobial sebum; home to protective skin flora.
- Inflammation: Reduces pathogen spread through vasodilation and recruitment of immune cells to damaged areas.
- Wound Repair: Involves blood clotting (platelet aggregation) and fibroblast activity for collagen deposition to close wounds.
- Mucous Membranes: Produce mucus to trap pathogens; ciliated cells help expel them.
- Gut Environment: Highly acidic stomach conditions destroy pathogens; gut flora inhibits harmful pathogen growth.

Plant Defences

Plants utilize physical defences like waxy cuticles and cell walls to prevent pathogen entry.
Callose: A polysaccharide that blocks pathogen entry during infections.
Plants secrete antimicrobial chemicals (e.g., saponins, phytoalexins) to combat pathogens and produce toxins to deter herbivores and insect vectors.

Activation of the Adaptive Immune Response

Antigen Presenting Cells (APCs): Macrophages and dendritic cells present antigens to activate T-cells.
Lymphocyte Types:
- T Cells: Kill pathogens and activate B cells; originate from bone marrow and mature in the thymus.
- B Cells: Produce antibodies and develop memory cells; activated by T-helper cells.

T Lymphocytes and Cell-Mediated Immunity

Clonal deletion eliminates lymphocytes that react to self-antigens, ensuring tolerance.
Steps of T-Cell Action:
- APCs present antigens to T-helper cells.
- T-helper cells activate cytotoxic T cells and B cells, producing cytokines to enhance immune response.
- Cytotoxic T Cells (TC) induce apoptosis of infected cells.
- Memory T cells provide long-term immunity.
- Regulatory T cells modulate immune responses.

Mechanism of Cytotoxic T Cells

Perforins create holes in infected cell membranes; granzymes enter through these holes to induce cell death.
Fas ligand binding activates apoptosis in target cells.
Infected cells release interferons to inhibit viral replication and enhance nearby cell defences.

B-Cells and Humoral Immunity

B cells respond to specific antigens through T-helper cell activation.
Following activation, B cells undergo clonal expansion, producing:
- Plasma B Cells: Short-lived cells that produce large quantities of antibodies during an initial infection.
- Memory B Cells: Provide faster and stronger responses during subsequent exposures to the same pathogen, known as immunological memory.

Overview of Antibodies

Antibodies are Y-shaped glycoproteins with unique structures for specific antigen binding.
Constant Region: Similar across all antibodies, used for phagocyte attachment.
Variable Region: Unique to each antibody, responsible for antigen specificity.

Antibody Functions

Neutralization: Antibodies can neutralize toxins or viral attachment sites to prevent infections.
Agglutination: Antibodies clump pathogens, facilitating phagocytosis.
Marking: Antibodies signal immune cells for targeting pathogens.
Lysis: Enzymatic reactions break down bacteria bound to antibodies.

Monoclonal vs Polyclonal Antibodies

Monoclonal Antibodies: Highly specific, targeting unique antigenic sequences.
Polyclonal Antibodies: Diverse binding sites, recognizing variants of specific antigens.

Functions of Monoclonal Antibodies

Treating Poisoning: Neutralize toxins in patients.
Cancer Treatment: Target tumor markers; enhance immune response.
Medical Diagnosis: Detect specific antigens in blood or tissue samples, e.g., pregnancy tests.### Monoclonal Antibodies Production
Injection of an antigen into a mammal stimulates an immune response, leading to the production of specific antibodies by B cells.
Spleen cells, which produce lymphocytes, are surgically removed from the animal for further processing.
The spleen cells are fused with myeloma (tumor) cells to create hybridoma cells, combining properties of both cell types.
Hybridoma cells can proliferate indefinitely while continuously producing monoclonal antibodies, which can be cultured in the lab.
Monoclonal antibodies are harvested from hybridoma cell cultures for various applications.

Natural Immunity

Develops post-infection through the body's response to pathogens, resulting in immunological memory.
Memory cells formed during primary infection enable rapid response to secondary infections by the same pathogen.
Mothers can transfer natural immunity to infants via breast milk, providing immediate protection.

Artificial Immunity (Vaccines)

Induced through vaccines, which contain inactivated or weakened viruses to stimulate immune responses.
Vaccines prepare the immune system by creating memory against specific pathogens, usually effective against viral infections.

Active Immunity

Generated when the body produces its own antibodies in response to an infection or vaccination.
Vaccination encourages the immune system to recognize and eliminate pathogens, often requiring booster shots to maintain immunity over time.

Passive Immunity

Acquired when ready-made antibodies are introduced from another organism, providing immediate but temporary protection.
Useful for rapid treatment of specific infections.

Importance of Vaccination

Vaccination enables quick immune responses, reducing the time the body needs to mount an effective defense against pathogens.
Many pathogens can cause significant harm in a short time, making timely vaccination crucial.

Herd Immunity

Achieved through widespread vaccination, crucial for protecting individuals who cannot be vaccinated, such as infants.
The breakdown of herd immunity due to decreased vaccination rates can lead to outbreaks of preventable diseases.

Ethics of Herd Immunity

Declining vaccination rates compromise herd immunity, allowing diseases to resurge that were previously controlled through vaccines.
Concerns about vaccine safety can undermine public health efforts, leading to severe consequences in vulnerable populations.

Risks of Vaccines

Vaccination is generally safe, but like any medical intervention, there can be side effects.
Public misconceptions can deter vaccination efforts, risking community health.

Antigenic Variability

Vaccines are effective based on the assumption that pathogen antigens remain constant; antigenic variation from pathogens challenges this efficacy.
Antigenic drift involves minor changes; antigenic shift refers to significant changes leading to new virus types.

Influenza Virus Case Study

Rapid mutation rates in influenza require annual vaccine updates to match circulating strains.
Unvaccinated individuals increase the chance of developing new strains through transmission of the virus.

Evolutionary Race Between Pathogens and Hosts

Pathogens, such as HIV and tuberculosis (TB), evolve to evade host immune responses.
TB spreads through respiratory droplets, featuring a thick cell wall that protects it within macrophages, allowing dormancy and reactivation.
HIV disrupts immune responses by targeting helper T cells and has a high mutation rate, leading to ineffective memory responses.

Bacteria and Toxins

Staphylococci produce exotoxins, which can severely disrupt host cellular processes.
Salmonella produces endotoxins that can provoke immune responses like inflammation and fever.

Antibiotics

Types include bacteriostatic (inhibit growth) and bactericidal (kill bacteria).
Penicillin, discovered in 1928, is a well-known bactericidal antibiotic.
Overuse of antibiotics leads to resistance, exemplified by MRSA and C. difficile infections, complicating treatment strategies in hospitals.

Investigating Antibiotic Effects

Antibiotic efficacy can be tested using agar plates with antibiotic-impregnated paper discs, measuring the cleared areas around discs post-incubation.

Other Medicines

Many medicines are derived from natural compounds, emphasizing the importance of biodiversity in discovering new therapeutic agents.
Personalised medicine tailors treatments to genetic profiles, aiming for maximum efficacy in individual patients.
Synthetic biology enhances drug development by creating new compounds or reengineering organisms for therapeutic purposes.

Pathogens and Infectious Diseases

Pathogens are organisms that cause diseases, including viruses, bacteria, protoctists, and fungi.
Infectious diseases are communicable conditions caused by pathogens that can be transferred between hosts.

Types of Pathogens and Associated Diseases

Viruses
- HIV/AIDS: host - humans
- Influenza: hosts - animals, including humans
- Tobacco mosaic virus: host - plants
Bacteria
- Bacterial meningitis: host - humans
- Cholera: host - humans
- Tuberculosis: hosts - animals (cattle) and humans
- Ring rot: host - plants (potatoes and tomatoes)
Protoctists
- Malaria: hosts - animals (including humans)
- Late blight: host - plants (potatoes and tomatoes)
Fungi
- Athlete’s foot: host - humans
- Ringworm: host - animals (cattle)
- Black sigatoka: host - plants (bananas)

Transmission of Infectious Diseases

Direct Transmission: Pathogens spread directly from one host to another.
- Droplet transmission: Inhalation of droplets from coughing, sneezing, talking, or spitting.
- Sexual transmission: Unprotected intercourse with an infected person.
Indirect Transmission: Pathogens spread via intermediaries before reaching the final host.
- Contaminated water/food: Ingestion of food/water tainted with pathogens.
- Spores: Asexual reproduction products from fungi and some protoctists, which can cause diseases upon entry into hosts.
- Vectors: Organisms carrying the pathogen to hosts, e.g., mosquitoes in malaria.

Detailed Look at Specific Diseases

Cholera

Infection caused by Vibrio cholerae, affecting the small intestine.
Symptoms include severe watery diarrhea, vomiting, and muscle cramps.
Transmitted mainly through the faecal-oral route via contaminated water and food.

Malaria

Caused by Plasmodium species, especially Plasmodium falciparum.
Symptoms: fever, headaches, skin yellowing.
Transmitted through the bite of infected female mosquitoes, allowing the parasite to enter the bloodstream and infect red blood cells.
Endemic in tropical and subtropical regions with conducive climates for mosquito breeding.

Tuberculosis (TB)

Caused by Mycobacterium tuberculosis in humans and Mycobacterium bovis in cattle.
Primarily affects the lungs but can impact other body parts.
Airborne transmission occurs through droplets when an infected person coughs, sneezes, or talks.

HIV/AIDS

Caused by the human immunodeficiency virus, leading to acquired immunodeficiency syndrome (AIDS).
Weakens the immune system, increasing vulnerability to infections and cancers.
Transmitted through blood, semen, body fluids, and has notable routes including:
- Sexual contact, needle sharing, vertical transmission from mother to baby, and breastfeeding.

Stem Rust

Caused by the fungus Puccinia graminis, primarily affecting wheat and barley.
Transmitted through spores that infect host plants, creating pustules that damage the plant's integrity.

Preventing Transmission of Infectious Diseases

Importance of prevention includes social and economic factors affecting transmission rapidly in crowded areas.
Investment in healthcare and public health education significantly lowers disease incidence.

Preventative Strategies

Cholera
- Ensure access to clean drinking water.
- Educate communities on hand hygiene.
- Provide sanitation facilities.
Malaria
- Eliminate mosquito breeding sites through sanitation improvements.
- Educate on protection using repellents and mosquito nets.
Tuberculosis
- Provide vaccinations.
- Educate on treatment access and disease control measures.
HIV
- Promote safe sex practices and needle usage.
- Educate on HIV treatments and the risks of breastfeeding.

Viral Life Cycle

Viruses do not divide like cells; they rely on host cells for replication and production of new viral particles.
The virus’s ability to infect a host cell is crucial for its reproduction.

Virus Attachment and Infection

Binding to Host Cells:
- Viruses utilize attachment proteins to attach to specific host cells.
- Different viruses have unique attachment proteins, dictating the type of cells they can infect, e.g., HIV binds to human T-cell receptors.
Injection of Nucleic Acids:
- Upon infection, viruses inject nucleic acids (DNA or RNA) into the host cell.
- This stage is termed the lysogenic cycle.
Injection of Unique Viral Proteins:
- Some viruses inject specific proteins to manipulate the host cell's machinery.
- This process diverts the host’s energy away from its own functions, focusing instead on producing viral genomes and proteins, causing harm to the host cell.

Viral Release and Impact on Host Cell

Release from Host Cell:
- Once a substantial number of viral particles are formed, they exit the host cell via lytic release, causing the cell to burst.
Host Cell Death:
- The original host cell dies due to damage from the viral escape, leaving a breach in its cell membrane.
- This stage is known as the lytic cycle.

Latency of Viruses

Latent Phase:
- After initial infection, viruses can enter a latent state during the lysogenic cycle, becoming dormant and ceasing replication of viral particles.
Reactivation:
- Latent viruses can be triggered to reactivate due to factors such as stress, resuming the production of viral particles and initiating the lytic cycle again.
- Reactivation can lead to illness in the host, even without reinfection from an external source.

Viral Life Cycle

Viruses replicate by infecting a host cell instead of undergoing cell division.
The success of viral reproduction is hinged on the ability to infect a host cell.

Virus Binding to Host Cells

Attachment proteins enable viruses to bind specifically to host cells.
Different viruses possess unique attachment proteins, determining the types of cells they can infect.
Example: HIV's attachment proteins bind to receptors on human T-cells.

Injection of Nucleic Acids

Following attachment, viruses inject their nucleic acids (DNA or RNA) into the host cell.
This stage is part of the lysogenic cycle, where the virus introduces its genetic material into the host.

Injection of Unique Viral Proteins

Some viruses can inject unique viral proteins into the host cell, aiding in hijacking the host's cellular machinery.
This manipulation redirects the host's energy from cellular functions to viral replication, severely harming the host cell.

Release from Host Cell

Viral particles accumulate and eventually burst from the host cell in a process known as lytic release.
Released viruses seek out new host cells to infect and continue their life cycle.

Host Cell Death

The original host cell dies from damage, particularly due to holes created in its cell membrane.
This stage is part of the lytic cycle, signifying the death of the host cell following viral replication.

Latency

Viruses can enter a latent state during the lysogenic cycle, becoming dormant and ceasing reproduction of viral particles.
Reactivation can occur due to various triggers, such as stress, leading the virus to resume production.
Reactivation allows the host to become ill without any new external viral infections, as the dormant virus becomes active again.

Structure of Viruses

Viruses are biological entities, distinct from living cells and organisms, characterized by a nucleic acid genome.
Viruses invade host cells to reproduce, often multiplying before the host immune system recognizes and responds to the infection.
Lacking cell organelles, viruses do not possess a nucleus, ribosomes, or any membrane-bound structures.
Every virus has a genome, which can include variations of DNA or RNA with up to 8 different genome types.
The protein coat, known as the capsid, encapsulates the viral genome, offering protection against environmental factors. Some viruses also feature a lipid envelope with glycoproteins.
Attachment proteins on the capsid's surface facilitate binding to host cells, crucial for viral infection.
Viruses are extremely small, typically in the nanometer range, making them smaller than the smallest prokaryotic cells.

Classification of Viruses

All viruses possess a capsid and a nucleic acid core, which serve as primary criteria for classification.
Lambda phage virus
- Hosts E. coli as its infective target.
- Features a prolate capsid structure.
- Contains double-stranded DNA.
Tobacco mosaic virus
- Infects plants.
- Exhibits a helical capsid structure.
- Composed of single-stranded RNA.
Ebola virus
- Infects humans.
- Has a helical capsid structure.
- Contains single-stranded RNA.
HIV
- Primarily infects humans.
- Displays a fullerene or cone-shaped capsid structure.
- Contains single-stranded RNA.

Structure of Viruses

Viruses are biological entities, distinct from living cells and organisms, characterized by a nucleic acid genome.
Viruses invade host cells to reproduce, often multiplying before the host immune system recognizes and responds to the infection.
Lacking cell organelles, viruses do not possess a nucleus, ribosomes, or any membrane-bound structures.
Every virus has a genome, which can include variations of DNA or RNA with up to 8 different genome types.
The protein coat, known as the capsid, encapsulates the viral genome, offering protection against environmental factors. Some viruses also feature a lipid envelope with glycoproteins.
Attachment proteins on the capsid's surface facilitate binding to host cells, crucial for viral infection.
Viruses are extremely small, typically in the nanometer range, making them smaller than the smallest prokaryotic cells.

Classification of Viruses

All viruses possess a capsid and a nucleic acid core, which serve as primary criteria for classification.
Lambda phage virus
- Hosts E. coli as its infective target.
- Features a prolate capsid structure.
- Contains double-stranded DNA.
Tobacco mosaic virus
- Infects plants.
- Exhibits a helical capsid structure.
- Composed of single-stranded RNA.
Ebola virus
- Infects humans.
- Has a helical capsid structure.
- Contains single-stranded RNA.
HIV
- Primarily infects humans.
- Displays a fullerene or cone-shaped capsid structure.
- Contains single-stranded RNA.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on key cells of the immune system, including neutrophils and macrophages. This quiz explores their functions, development sites, and roles in the immune response. Challenge yourself with questions on opsonins and phagocytosis.