Biology mod 7 pathogen table PDF

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Summary

Revision of Year 12 Biology for the course. Recommend as introduction if you haven't learnt biology before...

Description

Viruses: non-cellular

Prions: : non-cellular

Bacteria: : cellular

microorganism Feature s

*very small (30-300nm) - inner DNA/RNA core + capsid (protein coat) Types:

*Mutated prion proteins (relatively rare) - no genetic material as are proteins

*prokaryotes (0.5-110um) - no nucleus or organelles

*Comes into contact to promote abnormal folding of normal prion proteins to become infectious prion proteins => clumping of long fibres toxic to nerve cells => death of nerve cells => holes in nerve tissue

* via binary fission

*spores - zoospores (asexual and motile) - oospores (sexual and survive in extreme env.)

- Eating diseased beef brain tissue (causes vCJD) - Contamination thr surgery / growth hormone injection / cornea transplants - Inheritance of mutated gene - Spontaneous formation of infectious prion protein *Neurodegenerative disease: Creutzfeldt-Jakob disease (humans) / mad cow disease (Bovine spongiform encephalopathy - cows) - causes misfolded proteins (plaques & vacuoles) to form => killing neurons => holes in brain tissue - Symptoms: poor muscular coordination, death, spongy brain tissue, dementia

*contamination from - Soil - Water - Animals/insects - Wounds (tools)

*dispersed via water, soil, wind - Send out hyphen (fungal thread) to invade plant tissue

*tetanus *meningococcal disease *food poisoning *pneumonia *Soft rot disease (affects carrots, cabbage, onion, etc...)

*Phyphthora: one of the most invasisve plant pathogens which infects many economically viable crops (e.g. tomatoes, potato, apple, tobacco) and devastate natural ecosystems.

*Retrovirus (contains RNA) *Bacteriophages (infects bacteria) *viroids (only plant pathogens: less

Reprod uction method

complex single circular RNA strand - no capsid => compete for nucleotides & form viroids bundles which mechanically interfere with plant internal structures) *invades host cell for reproduction using transcription and translation mechanisms of host cells Exists as viroins outside host cells (vector stage where it can be transmitted)

Infectio n pathwa ys

- Vectors (Plants usually infected by insect vectors) - inhalation / ingestion - Mechanical means (enters wounds) - ovule of plants infected via infected pollen grain

Exampl es of disease

*measles, AIDS (caused by HIV), Herpes, SARS *Wheat streak mosaic virus (WSMV) causes severe damage to crops as plants either die prematurely, failing to grow or being stunted. The develop yellow streak and blotching in a mosaic pattern.

Protist - oomyctes (cellular microorganism) *protists causing blight, downy mildew in plants & life-threatening infections in animals - have motile cells w/ flagella, cellulose walls, cellular process not found in fungi

Features

Reproduction method Examples

Fungi: : cellular microorganism *unicellular (yeast) *eukaryotes (mushrooms) - causes disease & symptoms via secretion of digestive enzymes to break down organic matter

*budding/binary fission *athlete’s foot: break down keratin tissue of foot => inflammation & itchness - caused by species of Trichophyton, Epidermophyton, and Microsporum (fungi) - trasmitted via contact with infected surfaces &skin to skin contact which then enters thr. wounds in skin *thrush: vaginal yeast infection from overgrowth of Canind (usually found on intestinal & respiratory tract and vagina), due to pH changes (=> lacking normal micro bacterial env.) *blight: causes chlorosis (loss of green pigment), tissue browning, leaf and flower death *powdery mildew: causes white fungal blooms, blackening leaves

Protozoan: : cellular microorganism

Parasites: Macroorganism

*unicellular eukaryotes (1-300nm) - cell membrane + nucleus + organelles - Flagellates: has whip like tail - Ciliates: covered in cilia to move - Pseudopodia: project a foot to move - Sporozoa: reproduce via spore

*eukaryotes relying on host to provide nutrients - inject toxins or acts as vectors of disease *Endo-parasites - Reside inside host - Complete life stages inside host *Ecto-parasites - Reside outside host for a short period

*variety

*sexual reproduction: lays eggs

*Malaria: caused by Plasmodium protozoans transmitted via infected female mosquitoes (vector) *giardia lamblia infects small intestine of animals via water contaminated by infected faeces *African sleeping sickness caused by Trypanosome brucei transmitted by being bitten by the tsete fly

*ticks, mosquitoes, leeches, mites, lice *Helminths: endoparastic worms which feed on a live plant/animal host. Suppresses immune system of host - in plants: roundworms/nematodes infect roots of orchards - in animals: inc intenstinal worms (tapeworms, fluke, flatworms) which reside in intestines to prevent host's absorption of nutrients => weight loss, anaemia, nutrient deficiencies...