Prions, Viruses, Bacteria Flashcards
What is the difference between intracellular and extracellular organisms?
Intracellular:
- grow and multiply only in host cells
Extracellular:
- can grow outside cells
Explain prions.
- no test to determine them
- takes at least 20 years for prion to activate
- derived from a part of a protein found in neurons
- do not possess RNA or DNA
- causes a disease when it mutates to become resistant to proteases which normally control proteins in the body
- accumulates and damages neurons
- causes other proteins to turn into prions
What are prion associated diseases called and are they contagious?
Transmissible neurodegenerative diseases, and yes, they are HIGHLY contagious.
How can transmissible neurodegenerative disease be transmitted?
- injection
- contaminated material
- contaminated medical equipment
- contaminated meat
How are transmissible neurodegenerative diseases characterised?
- slowly progressive
- non-inflammatory neuronal degeneration
- causing loss of coordination, dementia, death (taking months to years)
Explain viruses.
- viruses cannot replicate outside the cell
- have no organised cellular structure
- consist of a protein coat (capsid) surrounding a nucleic acid core (genome) of RNA or DNA (never both)
Some viruses may have a lipoprotein envelop derived from the host cell. Explain
Enveloped viruses are continuously shed from the infected cell surface.
How are viruses characterised?
- type of viral genome (single or double stranded DNA or RNA)
- mechanism or reproduction
- mode of transmission
- type of disease produced
Give two examples of retro viruses.
- Human Immunodeficiency virus (HIV)
- Acquired Immunodeficiency Syndrome (AIDS)
How does the retrovirus replicate?
- enter the host cell
- viral RNA translated into DNA by viral enzyme called reverse transcriptase
- viral DNA copy integrates into the host chromosome and exists in a latent state
What are bacteria?
Autonomously replicating unicellular organisms known as prokaryotes because they lack an organised nucleus.
Explain the shape of a bacteria by the following:
- cocci
- spirilla
- bacilli
cocci - spherial
spirilla - helical
bacilli - elongate
How are bacteria most likely to reproduce? Explain the different divisions.
Most likely to reproduce by cellular division.
divide in chains - streptococci
divide in pairs - diplococci
divide in clusters - staphylococci
What are bacteria colonies called?
Biofilms
Bacteria are very adaptable and inhabit nearly all environments on earth. Name four environmental factors needed for bacteria to grow.
- nutrition
- light
- temperature
- humidity
- atmosphere
- the cell wall
