Infection and Response Flashcards
What are pathogens?
Pathogens are disease causing micro-organisms
E.g. bacteria, viruses, fungus, protists
What are Bacteria?
Bacteria are single celled organisms, prokaryotes - much smaller than eukaryotes
What are good uses of bacteria?
to make food like cheese and yogurt
to treat sewage
to make medicine
How do bacteria divide?
Binary fission (splitting in 2), reproduce rapidly
How do bacteria induce symptoms?
Bacteria produce toxins which affect the cells and make you feel ill, and sometimes directly damage and destroy cells
How do viruses induce symptoms?
Viruses take over your cells –> they live and reproduce inside your cells, damaging and destroying
What are 3 ways bacteria are spread?
- direct contact - STDs - can also infect person through cuts scratches and needle punctures that give access to blood, infected piece of a plant left in a field can infect new crops
2.air - droplet infection - tiny droplets are expelled when a person sneezes or coughs into the air. People nearby breathe in these droplets that contain pathogens
- Water - fungal spores in contaminated water can spread plant diseases. Humans eating raw uncooked contaminated meat
What is a group of bacteria called?
colony
What is aseptic technique + examples
-sterilise the work bench and all the equipment.
-sterilise hands and wear sterile gloves
-sterilise innoculating loop in blue flame
-open vial containing bacteria at an angle, close to the flame of the bunsen burner to maintain a sterile field
-open petri dish at an angle close to the flame of the bunsen burner
-sterilise innoculating loop before and after each use
What is growth of bacteria affected by?
growth rate of bacteria is affected by temperature, available nutrients, O2, pH
What is a vaccine
a dead or inactive antigen
What are viruses?
Viruses are even smaller than bacteria
Viruses take over your cells –> they live and reproduce inside your cells, damaging and destroying
What are the right conditions to culture bacteria in?
a culture medium ( agar gel), warmth and oxygen
Where can unnecessary contamination come from? (bacteria growth)
skin, the air, soil, water - this must be avoided - harmless bacteria can mutate into harmful bacteria
What aseptic techniques must be used before and whilst growing and preparing to grow bacteria?
-sterilise the work bench and all the equipment.
-sterilise hands and wear sterile gloves
-sterilise innoculating loop in blue flame
-open vial containing bacteria at an angle, close to the flame of the bunsen burner to maintain a sterile field
-open petri dish at an angle close to the flame of the bunsen burner
-sterilise innoculating loop before and after each use
What temperature is bacteria cultured at and why?
cultures are incubated at 25 degrees celsius as if it is closer to human body temp (37) then any mutating bacteria can become very harmful
What is growth of bacteria affected by?
temperature, available nutrients, O2, pH
How do you calculate growth of bacteria?
bacteria at the end of the growth period = bacteria at start of growth period x 2 ^number of divisions
What are ways to prevent the growth of bacteria?
- raise or lower the temperature
- disinfectant - kills bacteria in the ENVIRONMENT
- antiseptic - kills bacteria that is safe to use on the skin
- antibiotics - kills bacteria and is safe to use IN the body