Bacteria And Viruses Flashcards
What is meant by the term antimicrobial properties?
Ability to kill bacteria
Why are bacteria mixed with agar?
Source of nutrient
Why does the Petri dish need to be sterile?
Prevent contamination by other bacteria
Prevent competition between bacteria
Makes sure the investigation is valid
Why must the Petri dish not be completely sealed by tape?
Lack of oxygen causes anaerobic respiration
Harmful bacteria grow as a result
What temperature should bacteria be grown in a school? Why?
25°C
Because bacteria that can’t survive at body temperature (37°C) would grow
Less risk of illness
Why does a disc of a substance that has antimicrobial properties that is placed in a Petri dish have no bacteria growing around it?
Zone of inhibition
Substance in the disc kills bacteria
This is through diffusion of the substance from the disc
Name a substance both bacteria and viruses have
Nucleic acid
Name something a bacteria has that a virus doesn’t
Cytoplasm
Name something that a virus has but a bacteria doesn’t
Protein capsid
Name two types of cell that HIV enters in the immune system
T helper
Phagocytic eg macrophages
How is HIV able to enter T helper cells?
Glycoprotein molecules, called gp120, on the virus surface, bind with CD4 receptors on the surface of the T helper cell
Virus envelope fuses with cell membrane
What happens in macrophages are infected with HIV?
Phagocytosis
What is the acute phase in HIV?
HIV antibodies appear in the blood after 3-12 weeks
Person may experience fever, sweats, headache, sore throat and swollen lymph nodes
However they may show no symptoms
Virus replicates rapidly and T helper cell numbers decrease
After a few weeks T helper cells are killed by The killer cells
This reduces the rate of virus replication
