Topic 6.2: Cause of Death Flashcards
What type of cell is Bacteria?
A Prokaryotic cell
Bacteria
- No nucleus.
- Lack of membrane bound organelles.
- Do not produce a spindle during cell division.
- Reproduce asexually by binary fission.
What happens to Bacteria after replication?
After replication of their DNA they divide into two identical cells.
Ribosomes
Site of protein synthesis; occur free in the cytoplasm.
Capsule
Mucus layer for protection
To prevent dehydration
Allows bacteria to form colonies
Pilus (Plural pili)
Protein tubes that allow bacteria to attach to surfaces
Involved in cell-to-cell attachment
Plasmids
Small circles of DNA
Mesosome
Infolding of the cell surface membrane
Site of cell respiration
Flagellum
Used for cell movement
Cell Wall
Does not contain cellulose.
Made of peptidoglycan: polysaccharide that is cross linked by peptide chains.
Gram positive bacteria
Walls are thickened with additional polysaccharides and proteins.
Gram negative bacteria
Thinner walls but with a surface layer of lipids for protection.
What are Viruses?
Strands of nucleic acid (RNA or DNA) enclosed within a protein coat.
Viruses
- Viral DNA can be single stranded or double stranded.
- Virus outer envelope is taken from the host cells surface membrane. Envelope has lipids and proteins.
- Viral envelopes have glycoproteins from the virus itself. Antigens.
What do antigens do?
Antigen molecules are recognised by the host’s immune system as not being it’s own self.
What does the envelope help do?
Envelope helps the virus attach to the cell and penetrate the surface membrane. An example is HIV.
What do viruses lack?
Viruses lack some of the internal structures for growth and reproduction. Therefore disrupts normal working of cell.
How do viruses reproduce?
- Virus attaches to the host cell.
- Virus inserts nucleic acid.
- Viral nucleic acids replicate.
- Viral protein coat synthesised.
- New virus particles are formed.
- Virus particles released due to lysis.
What are pathogens?
Bacteria and viruses that cause disease.
How is TB Bacterium transmitted?
Mycobacterium tuberculosis carried is carried in the droplets of mucus and saliva released into the air when an infected person talks.
Ways of TB Transmission
- Inhaling infected droplets. Known as droplet infection.
- Droplets can remain suspended for several hours in poorly ventilated areas.
- Close contact with an infected person increases risk of developing the disease: poor health + poor diet and overcrowding conditions.
Why is HIV considered a “weak” virus?
Because it cannot survive outside the body for significant time.
How is HIV transmitted?
- Passed only in body fluids, such as blood, vaginal secretions and semen (not saliva or urine).
- For infection to occur: body fluids have to be transferred directly into the body.
Ways of HIV Transmission
- Sharing needles.
- Unprotected sex.
- Blood-to-blood transfer through cuts and grazes.
- Maternal transmission from mother to unborn.
