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Biology > 6.1 > Flashcards

6.1 Flashcards

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1
Q

define pathogens

A

micro-organisms that cause disease

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2
Q

what is a culture

A

microorganisms are provided with the nutrients, level of oxygen, pH & temp that they require to grow large numbers so they can be observed & measured

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3
Q

why do aseptic techniques need to be carried out when culturing

A

risk that the bacteria mutates & becomes pathogenic (even if it wasn’t to begin with)
risk of contaminating with pathogenic microorganism & growing it
could contaminate pure samplesd

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4
Q

define sterile

A

something that is free from living microorganisms and their spores

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5
Q

how do you dispose of culture

A

seal in plastic bag
sterilize at 121’C for 15mins under high pressure

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6
Q

what is nutrient broth

A

a liquid nutrient for culturing microorganisms commonly used in flasks test tubes or bottles

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7
Q

what is nutrient agar

A

a jelly extracted from seaweed used as a solid nutrient for culturing, used in petri dishes

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8
Q

what is selective medium

A

a growth medium for microorganisms contaminating a very specific mixture of nutrients, so only a particular microorganism will grow on it

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9
Q

what is inoculating

A

the process by which microorganisms are transferred into a culture medium under sterile conditions

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10
Q

state 3 ways to grow a pure culture

A

grow under anaerobic/aerobic conditions

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11
Q

what is a hemocytometer

A

a thick microscope slide with a rectangular indentation and etched grid of lines that is used to count cells

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12
Q

what stain can be used to count only living cells

A

trypan blue
stains dead cells blue so only living cells can be counted

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13
Q

what is a turbidimetry

A

a method of measuring the concentration of a substance by measuring the amount of light passing through it

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14
Q

define turbid

A

something that is opaque or thick with suspended matter

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15
Q

what is dilution plating

A

a method used to obtain a culture plate with a countable number of bacteria colonies

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16
Q

what is a total viable cell count

A

a measure of the number of cells that are alive in a given volume of culture

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17
Q

how can you measure the growth of fungi

A

measure the diameter of the patches of mycelium

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18
Q

how can you measure the mass of cultured fungi

A

remove a sample from the separate the fungi & the liquid using a centrifuge or filtering
dry thoroughly at 100’C overnight then measure the mass

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19
Q

what is the time between bacterial divisions called

A

generation time

19
Q

what limits the reproduction of bacteria

A

limited nutrients & space
build up of waste products

19
Q

what is lag phase

A

when bacteria are adapting to their new environment are not yet reproducing at their maximum rate

20
Q

what is log phase/exponential phase

A

when the rate of bacterial reproduction is close to or at its theoretical maximum, doubling in a given time period

21
Q

what is stationary phase

A

when the total growth rate is 0 as the number of new cells formed by binary fission is equal to the number of cells dying

22
Q

what is the death phase

A

when reproduction has almost ceased and the death rate of cells is increasing

23
Q

give an example of waste product of bacteria leading to their decline

A

CO2 produced in respiration builds up and lowers the pH to a point where bacteria can no longer grow

24
Q

define endotoxins

A

lipopolysaccharides that are an integral part of the outer layer of the cell wall of gram (-) bacteria

25
Q

what are the symptoms produced by bacterial endotoxins

A

fever, vomiting & diarrhoea

26
Q

how is salmonella spread

A

ingestion of food & water contaminated with infected feces

27
Q

state 3 ways to avoid salmonella

A

cook all meat thoroughly wash hands after handling raw meat & using the toilet
avoid contaminated water

28
Q

what are exotoxins

A

soluble proteins that are produced and released into the body by bacteria as they metabolize and reproduce in the cells of their host

29
Q

which bacteria are exotoxins produced by

A

both gram (+) and gram (-) bacteria

30
Q

what are some of the effects of exotoxins

A

damage cell membranes
-causing cell breakdown or internal bleeding
act as a competitive inhibitor to neurotransmitters
directly poison cells
-fatal bacterial diseases

31
Q

give 3 facts about staphylococcus

A

only cause disease if they get inside tissues of the body
gram (+) bacteria
produce exotoxins that can cause mild skin diseases to rapid death

32
Q

state the third way that bacteria act as a pathogen

A

invade host tissues and damage cells

33
Q

what is tuberculosis

A

a lung disease caused by Mycobacterium tuberculosis & M.bovis

34
Q

how is TB spread

A

droplet infection; coughing, sneezing
drinking infected milk
working close to cattle

35
Q

what are the symptoms of tb

A

affects respiratory system damaging & destroying lung tissue
suppresses the immune system
coughing up blood

36
Q

what is primary infection

A

the initial stage of tb when it has been inhaled evaded the cells and multiplied slowly but often causes no symptoms

37
Q

what is a tubercule

A

the result of a healthy immune response to an infection, a localized inflammatory response forms a mass of tissue containing dead bacteria & macrophages

38
Q

what adaptation allows tb to survive primary infection

A

bacteria produce a thick waxy outer layer to protect them from enzymes of macrophages
remain dormant in tubercules in the lungs
until immune system has weakened

39
Q

define antibiotic

A

a drug that either destroys microorganisms or prevents them from growing & reproducing

40
Q

what does selective toxicity mean

A

that a substance is toxic against some types of cells and organisms but not others

41
Q

what is penicillin

A

the first antibiotic discovered
it affects the formation of bacterial cell walls and it is bactericidal

42
Q

what’s the difference between bacteriostatic & bactericidal antibiotics

A

bacteriostatic - inhibit growth of bacteria
bactericidal - kill bacteria

43
Q

state 6 factors which antibiotic effectiveness depend upon

A

concentration of the drug in the area of the body infected
how easily the drug can reach the tissue
how quickly it is excreted
local pH
susceptibility of pathogen
whether pathogen/host tissue can destroy the antibiotic

44
Q

what is antibiotic resistance

A

micro-organisms that are not affected by an antibiotic even if they have been effected in the past

Biology (33 decks)

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