All Module 4 Flashcards
Name 4 groups of pathogen that can cause communicable diseases.
● bacteria
● fungi
● protoctista
● viruses
How does Mycobacterium tuberculosis cause disease?
- Triggers inflammatory response by infecting phagocytes in lungs.
- Infected phagocytes are sealed in waxy-coated tubercles so bacteria remain dormant. First infection has no symptoms.
- If another factor weakens immune system, bacteria become active & destroy lung tissue
How does HIV result in the symptoms of AIDS?
- Attachment proteins bind to complementary CD4 receptor on TH cells.
- HIV particles replicate inside TH cells, killing or damaging them.
- AIDS develops when there are too few TH cells for the immune system to function.
- Individuals cannot destroy other pathogens & suffer from secondary diseases/ infections. May cause death.
How does the tobacco mosaic virus cause disease?
Affects plants. Mainly transmitted via infected sap.
Contains ssRNA, which is directly transcribed by host cell to assemble new virions.
Virions enter other cells via plasmodesmata then enter xylem & phloem.
Causes stunted growth & mottled leaves.
How does the influenza virus cause disease?
How does the influenza virus cause disease?
Transmitted via: droplet infection, contact with mucus containing virus, zoonotic infection, contact with fomites.
Injects viral RNA into ciliated epithelial cells of throat & lungs. Viral RNA hijacks cell biochemistry to produce new virions. Cell lysis releases virions.
5-7 days of headache, coughing, sneezing, sore throat,
vomiting, fever, muscular/joint pain.
What causes malaria?
Female Anopheles mosquito acts as vector for Plasmodium spp. protoctista when it transfers saliva to another organism during feeding.
Parasite reproduces asexually in red blood cells in liver, causing lysis.
What causes potato/ tomato late blight? What causes ring rot of potatoes?
Blight: The protoctista Phytophthora infestans behaves similarly to a fungus. Mainly transmitted via spores.
Ring rot: Sepedonicus subspecies of the bacterium Clavibacter michiganensis. Mainly transmitted by planting infected seeds/ contact with fomites. Plant-to-plant transmission is rare.
What causes bacterial meningitis?
Often meningococcal bacteria A, B, C, W, X, Y, Z. Also caused by pneumococcal bacteria & Haemophilus influenzae type b (Hib) bacteria. Affects meninges (protective membranes around brain).
Transmitted by droplet infection & direct contact with saliva e.g. kissing. Usually spread by carriers of the bacteria who are not ill & occasionally by individuals with meningitis.
Describe the chemical defences plants use against pathogens.
Terpenoids (essential oils) e.g. menthols act as antibacterials.
● Phenols e.g. tannin inhibit insects from attacking by interfering
with digestion.
● Alkaloids e.g. caffeine & morphins deter herbivores from
feeding because they taste bitter.
● Defensins (cysteine-rich proteins) inhibit transport channels.
● Hydrolytic enzymes e.g. chitinases break down cell wall of
invading organisms.
Outline the process of inflammation.
- Damaged vessels release histamines, causing vasodilation.
- Blood flow & permeability of blood vessels increase.
- White blood cells & plasma move into the
infected tissue.
How does blood clotting occur?
- Blood platelets form plug & release chemicals that enhance clotting e.g. thromboplastin.
- Prothrombin changes into thrombin, its active form.
- Fibrinogen changes into insoluble fibrin which covers wound.
Name the 2 types of white blood cell involved in phagocytosis.
Neutrophils
Macrophages (can become antigen-presenting cells)
Explain the role of antigen-presenting cells (APCs).
Macrophage displays antigen from pathogen on its surface (after hydrolysis in phagocytosis).
Enhances recognition by TH cells, which cannot directly interface with pathogens/ antigens in body fluid.
Secrete cytokines that are involved in stimulating specific immune response.
Name the 2 types of specific immune response.
cell-mediated ● humoral
What is biodiversity?
The variety of living organisms. It can be measured in terms of species diversity (number of species in a community), habitat diversity (range of different habitats) and genetic diversity (variety of alleles within a species).
