Topic 6B: Bacterial And Viral Infections Flashcards
Give some structural differences between viruses and Bacteria (4)
- Bacteria are much bigger in size
- Viruses have no plasma membrane (capsid) wheras bacteria have polysaccharide cell wall
- Viruses contain no cytoplasm
- Viruses contain no ribosomes
- viruses contain only one type of nucleic acid, Bacteria have 2
What is a pathogen?(2)
- Any organism/microorganism that causes disease
- Diseases caused by pathogens are called infectious diseases
How does HIV affect the immune system?
-Infect and destroys t helper cells which act as a host cell for virus
How is HIV spread?
Through infected bodily fluid coming into contact with mucosal surfaces
Describe the process of HIV replication(6)
– Attachment protein attaches to receptor molecule on cell membrane post
– Capsid released into cells where it uncoats and releases genetic material (RNA) into cytoplasm
– Reverse transcriptase used to make complimentary strand of DNA from viral RNA template
– New double-stranded DNA inserted into human DNA
– Host cell enzymes used to make fibre proteins from viral DNA
– Fire proteins assembled into new viruses which live via exocytosis
People infected with HIV eventually developed AIDs
Describe and explain the likely sequence of symptoms found in a person infected with HIV virus (6)
– Initial infection may lead to severe flu like symptoms well HIV replicates rapidly
– Latency period follows in which HIV replication drops to lower level and infected person went to experience symptoms
– Passing with HIV classed as having AIDS when symptoms of feeling immune system start to appear all T-helper cell count drops below a certain level
– Initial symptoms of aids include minor infections of mucus membranes, recurring respiratory infection caused by low t helper cell count
– After AIDs progresses number of T-helper cells decrease further patient becomes susceptible to more serious infections I.E.chronic diarrhoea/ serious bacterial infection /TB
– during late stages of AIDS patient has very low number of T-helper cells and suffer from a range of serious infections could kill them such as toxoplasmosis
What is AIDS?
Condition where are immune system deteriorates and eventually fails
When are people with HIV classed as having aids?(2)
– when symptoms of feeling immune system start to appear
– T-helper cell count drops below certain level
what are opportunistic infections?
When Diseases and infections that wouldn’t cause serious normally in people with a healthy immune system cause problems
What causes the length of time that people survive aids to very?
– Age
– Existing infections
– Strain of HIV
– Access to health care
What type of Cell does HIV replicate in?
T helper cells
What bacteria causes tuberculosis?
Mycobacterium tuberculosis
What is the cause of infection with TB?
Tiny droplets containing bacteria are inhaled into lungs (TB is an airborne bacteria)
What happens when Mycobacterium tuberculosis enters the lungs?(2)
- Bacteria taken up by phagocyte (able to evade digestion)
- Bacteria survive & replicate in phagocyte
Why don’t people infected with Mycobacterium tuberculosis develop TB straightaway?
Immune system seals of infected phagocytes in tubercles
-When sealed inside tubercle, bacteria becomes dormant and infected person show no obvious symptoms
