B4 Flashcards
(28 cards)
What is antibiotic resistance?
When bacteria evolve to become able to survive exposure to antibiotics
Describe how antibiotic resistance happens
A population of bacteria infect a body, the person takes antibiotics to kill the bacteria, some bacteria have a random mutation that makes them less susceptible or completely resistant to the antibiotic. The antibiotic kills the bacteria except for those that are resistant, the resistant strain now has more resources and reproduce. More mutations arise, leading to greater resistance and there is now a strain of bacteria that can’t be killed by antibiotics
Are antibiotics effective for viral infections?
No, they only work on bacterial infections
Give 3 reasons antibiotic resistance is becoming more common
Doctors prescribing antibiotics in cases that don’t require them, patients not taking the full course of antibiotics and huge amounts of antibiotics being given to farm animals to make them grow faster
Why is antibiotic resistance a problem?
If more bacteria are resistant to antibiotics we won’t be able to treat bacterial infections meaning more people will die from them
What are the conditions needed for bacterial growth and why?
Temperature - most bacteria grow fastest in warm environments
Nutrient availability - bacteria need a good supply of nutrients in order to grow rapidly
Moisture - most bacteria grow fastest in mist conditions
Oxygen - different types of bacteria either need the presence or absence of oxygen for growth
What is nutrient broth?
A nutrient rich liquid medium
What is agar jelly?
A nutrient rich gel medium
How do bacteria grow in agar jelly?
They grow in colonies that are visible to the naked eye and contain millions of bacterial cells
What are aseptic techniques used for?
They are used to prevent contamination of a substance by bacteria
What are 5 examples of aseptic techniques for the growth of bacteria?
Cleaning surfaces with disinfectant - cleaning the work area before and after use with alcohol
Washing hands with aseptic soap before handling micro-organisms
Sterilising all instruments, solutions and mediums before they are used by heating them until the micro-organisms are destroyed
Growing bacteria in incubators set to 25 degrees, preventing harmful bacteria that grown at body temperature (37 degrees) from growing
Creating a sterile field with the updraft of a flame
What nutrients to bacteria need to be cultured?
Carbohydrates for energy, nitrogen compounds for protein synthesis, vitamins and minerals
What is inoculation?
The process of transferring bacteria from a broth to an agar plate
Describe steps 1 to 3 of growing bacterial colonies
Sterilise an inoculation loop by placing it into a Bunsen burner until it is red hot
Hold the inoculation loop in the sterile field area and allow it to cool
Remove the lid from the bacterial culture bottle
What is a sterile field and how is it created with a Bunsen?
A sterile field is an area containing no bacteria and is created by the upward convection currents of hot air from the flame
Describe steps 4 to 6 of growing bacterial colonies
Place the neck of the bottle in the Bunsen burner flame, moving air out of the bottle and preventing other microorganisms from entering the bottle and contaminating the solution
Dip the sterilised inoculation loop into the bacterial culture flask
Hold the neck of the bottle in the flame again and replace the flask
Describe steps 7 to 9 of growing bacterial colonies
Slightly lift the petri dish
Make zigzag streaks gently and carefully across the surface of the agar jelly with the inoculating loop
Quickly replace the petri dish lid
Describe steps 10 to 12 of growing bacterial colonies
Secure the lid of the petri dish
Store the petri dish upside down in an incubator
Ensure that in schools and colleges the maximum temperature in the incubator is 25 degrees C to prevent the growth of harmful bacteria
What is step 13 of growing bacterial colonies?
Sterilising the inoculating loop again and disinfecting all work surfaces
What is a zone of inhibition?
A circular area around the antibiotic placed into the colony in which the colonies do not grow
What does a large and small zone of inhibition mean?
A larger zone of inhibition means that the antibiotic is more effective at killing bacteria
What is the order of evolution from chimpanzees to humans?
Chimpanzee, (Ardipithecus), (Australopithecus), (Homo Erectus), (Homo Sapiens)
What species, age and location was Ardi?
Species: (Ardipithecus ramidus)
Age: approx. 4.4 million years old
Location: Ethiopia
What were the key features of Ardi?
It had a small skull, and therefore a small brain size similar to that of a chimpanzee, it had opposable, grasping big toes for climbing, like an ape. It had long arms with grasping hands, and short legs, like an ape, its leg and pelvis structures show it walked upright like a human and its hand bone structure shows she did not use her hands to walk
