Identifying Pathogens Table VCE Biology PDF

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Summary

VCE Biology Pathogens Table...

Description

NAME

CELLULAR OR NONCELLULAR

PHYSICAL FEATURES

Non-cellular 20-400 nanometres in diameter

 Have protein coats surrounding nucleic acids (either DNA or RNA but not both)

 Steps to viral reproduction (lytic cycle) include: 1. Virus bind to the surface of the hosts cell 2. Viral DNA enters the cell’s cytoplasm 3. Viral DNA controls and directs the host cells machinery to replicate the viral proteins and DNA 4. New viruses are assembled – DNA is packaged inside and other components are added 5. Host cell undergoes lysis and dies – the infectious virus particles are released which can infect other host cells

PRIONS

Non-cellular 10 nanometres in size

 Misfolded proteins with no genetic material  Reproduce asexually

Normal prions naturally exist within the body 1. The infectious and abnormal conformation prion protein (PrP-res) touches the normal prion proteins that exist naturally in our bodies (PrP-sen) 2. This stimulates the secondary structure of the PrP-sen to change to create more infectious prions 3. PrP-res proteins tend to stick together, which over time can form long chains called amyloid fibres o Amyloid fibres are toxic to neuron cells and ultimately kill them (seen in Alzheimer’s patients)

BACTERIA

Cellular 1 micrometre in diameter

 Unicellular prokaryotes  Reproduce using binary fission  Different shapes:  rod-shaped (bacilli)  spherical-shape (cocci)  spiral-shaped (spirilla)  curved rod (vibrio)  May join to form chains or clusters  Some have flagellum for movement  Some have a capsule to help with adhesion to surfaces

 Some produce toxins that are released into the extracellular fluid  Some produce endospores that allow them to disperse to new hosts even in extreme conditions

 Single or multicellular eukaryotes  Have a cell well of chitin rather than cellulose  Can affect both plants and animals o Reproduce by producing spores

 Secrete digestive enzymes and other chemicals into the environment to break down organic matter which can be absorbed into the fungus o These enzymes kill the host cells and fungi then live off dead and dying tissue o Some fungi obtain nutrients from the living cells of their host.

VIRUSES

FUNGI

Cellular 10 micrometres to 3.8 kilometres wide

TREATMENT METHODS

METHOD OF ACTION/EFFECT ON THE BODY

Immunisations Antiviral drugs – suppress reproduction or viruses

EXAMPLE

Varicella zoster

Bovine Spongiform Encephalitis





Can be treated through antibiotics – used internally to destroy bacteria and inhibit growth Disinfectants and antiseptics – used externally to destroy bacteria

Fungicides – chemicals that destroy fungi

Staphylococci

Trichophyton...