Biology - Module 4

What is everything you need to know about tuberculosis?

Pathogen: Bacteria

Symptoms: Blood coughing, fever, chest pain, chills, night sweats, weight loss

Treatments: Antibiotics or vaccination

What is everything you need to know about bacterial meningitis?

Pathogen: Bacteria

Symptoms: Fever, headaches, stiff neck, light sensitivity, vomiting, confusion, a “rash” not fading under a glass

Treatment: Antibiotics, preventable through vaccines

What is everything you need to know about ring rot?

Pathogen: Bacteria

Symptoms: Wilted/rotten plant (most often potato)

Treatment: Leaving pathogens without food

What is everything you need to know about TMV?

Pathogen type: Virus

Symptoms: Spots created which stop photosynthesis and kill chloroplasts

Treatment: Destroying infected plants

What is everything you need to know about influenza?

Pathogen type: Virus

Symptoms: Muscle pain, headache, fever

What is everything you need to know about cattle ringworm?

Pathogen type: Fungus

Symptoms: Fungal growth causing rash

Treatment: Like all fungi, can be treated through fungicide

What is everything you need to know about athlete’s foot?

Pathogen type: Fungus

Symptoms: Growth of fungi on the feet

Treatment: Cream on feet

What is everything you need to know about black sigatoka?

Pathogen type: Fungus

Symptoms: Spots on bananas reduce the yield

How does malaria spread and develop?

• A mosquito bites a person

• Plasmodium protists travel to the liver in form of sporozoites, becoming a merozoite once in the liver

• They then reach red blood cells and grow while reproducing

• They reporduce asexually inside the body and sexually outside

• This causes recurrent fever and can lead to coma and death

What is potato blight?

In leaves and tubers, it is a protist that kills plants

How does the intestine and anus stop bacterial growth?

Intestine: Good bacteria outcompete pathogens

Anus: Expels pathogens

How do inflammatory responses work?

• Destroyed cells release histamines and cytokines

• These cause localised heat, redness and swelling

• They attract white blood cells to “clean up” the area

How do clots form?

• Clots seal wounds

• Thromboplastin works with calcium ions to produce fibrin and ultimately a clot

• Serotonin causes contractions of blood vessels

• A scab forms

How does fever help us?

• Increases temperature so enzymes can’t work from pathogens

• Antibodies are also made faster at higher temperature

What are neutrophils and macrophages?

Neutrophils: Lobed nucleus to engulf a pathogen, going through pores

Macrophages: Round nucleus, combines glycoproteins and antigens

What steps occur in phagocytosis?

1. Chemicals produced by a pathogen attract neutrophils

2. Phagocyte finds a foreign antigen

3. Cell membrane of the phagocyte fuses, trapping pathogen

4. Digestive enzymes emptied into pocket containing pathogen, digesting the pathogen

5. Useful products diffused into the cell, others taken off, antigens put on edge of cell for display

What are the four types of T-cells (or lymphocytes)?

Killer-T: Attaches to antigens using a chemical called perforins

Helper-T: Secretes interleukins, activates other T and B cells (consider them the alarm clock of the immune system)

Memory-T: Stored in lymph nodes to provide immunity after survival of, or vaccination against, an infection

Regulator-T: Reduces the response after a week to prevent the immune system causing unnecessary damage

What do all T-cells have in common?

• Maturing in the thymus

• Receptors bind to antigens

• Clonal selection - binding to activate an immune response, done by specific T-cells with specific antigens

• Clonal expansion - dividing to form many of its own kind after clonal selection

How do Helper T-cells work?

• Releasing interleukins (a form of cytokine that can tone up the response)

• Stimulating clonal expansion

• Activating B cells to make antibodies

• Activating Killer-T

• Attracting macrophages

How do memory-T cells work?

• Last a long time

• Dividing rapidly to form killer-T cells and destroy pathogens

How do suppressor/regulatory T-cells work?

• Switching off or reducing immune response

What are B-cells?

• Lymphocytes that mature in bone marrow

• They are covered in antibodies

How do they use clonal selection and expansion?

Selection: Interleukins from helper-T activate B lymphocytes, activated directly when binding to an antigen

Expansion: Divides into plasma and memory cells

What is the humoral response they undergo?

• A macrophage will ingest a pathogen, displaying an antigen

• The helper T cell + antigens activate B cells, with it undergoing mitosis en masse

What do they split into and what are the functions of each?

Plasma cells: Secrete a specific antibody, transported between the blood and lymph nodes

Memory B: Secretes antibody for years, reproduces rapidly if another attack occurs

How does immunity occur?

A specific antigen receptor is triggered, causing more plasma cells to be produced

What is a secondary response? What happens during it?

An infection when immunity has been reached - plasma cells will be made and memory T cells will make more killer T