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A Level Biology: Topic 6 (Edexcel) > Bacteria and Disease > Flashcards

Bacteria and Disease Flashcards

1
Q

Why is it important to use aseptic techniques when culturing microorganisms?

A

Mutant strain may be pathogenic
It could be contaminated with a pathogenic bacteria in the environment
Any other type of organism will contaminate it

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2
Q

What is a selective medium?

A

A growth medium containing very specific nutriants so only a particular type of microorganism will grow on it

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3
Q

What is a haemocytometer?

A

A microscope slide with a grid on it used to count cells

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4
Q

How is a cell culture perpared to be used on a haemocytometer?

A

Stained with trypan blue which indicates dead cells

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5
Q

What is turbidimety?

A

Measuring the concentration of a substance by seeing how much light passes through it

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6
Q

What is dilution plating?

A

Where you measure a culture by diluting the sample until you are able to count individual colonies.

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7
Q

What ways can you measure cell colonies?

A

Haemocytometer
Turbidimety
Dilution plating

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8
Q

What are the phases of cell growth in colonies?

A

Lag phase
Log phase
Stationary phase
Death phase

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9
Q

What is the leg phase of cell colonies?

A

The bacteria are adapting to their environment and are not repriducing at their maxiumum rate

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10
Q

What is the log phase of cell colonies?

A

When reproducton is at is maximum and repeatedly doubles in a given time period

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11
Q

What is the stationary phase of cell colonies?

A

The growth rate is 0 because the new cells are equal to cell death

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12
Q

What is the death phase of cell colonies?

A

The death rate of cells is increasing and reproduction is almost stopped

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13
Q

Whyc can’t bacteria continue to grow at an exponential rate?

A

Less nutrients avaliable

Buildup of waste products

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14
Q

What are the two types of toxins that bacterial cells can have?

A

Endotoxins

Exotoxins

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15
Q

What are endotoxins?

A

Lipopolysacchardies that are part of the outer layer of the cell wall in gram-negative bacteria

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16
Q

What are exotoxins?

A

Soluable proteins releaced by bacteria into the body that metabolise and reproduce in host cells

17
Q

What is selective toxicity?

A

They interfere with the metabolism or function of the pathogen without damaging host cells

18
Q

What is the function of antimetabolites?

A

They are a type of antibiotic that interupts metabolic pathways such as blocking nucleic acid synthesis which causes death

19
Q

What is the function of protein synthesis inhibitors?

A

They are a type of antibiotic that interrupt or prevent transcripiton/translation so protein production is affected

20
Q

What is the function of cell wall agents?

A

They are a type of antibiotic that prevent the formation of cross linking in cell walls so bacteria burst

21
Q

What is the function of cell membrane agents

A

They are a type of antibiotic that they damage the cell membrane so water moves in and kills the cell

22
Q

What is the function of DNA gyrase inhibitors?

A

They are a type of antibiotic that stops bacterial DNA from coiling up so it no longer fits in the cell

23
Q

What does it mean when an antibiotic is bacteriostatic?

A

They inhibit the growth of bacteria

24
Q

What does it mean when an antibiotic is bactericidal?

A

It destroys almost all of the pathogens

25
Q

What affects the effectiveness of drugs?

A

concentration
local pH
pathogen

26
Q

How do bacteria become resistant to antibiotics?

A

Some will have a mutation that allows them to survive so only they will pass their genetics on, meaning a higher proportion of bacteria are resistant

27
Q

How does using antibiotics speed up the process of resistance?

A

It provides a selection pressure that selects for resistant bacteria

28
Q

How can be reduce the development of antibiotic resistance?

A

Vary the antibiotics we use and find new ones

29
Q

What are healthcare-associated infections?

A

Infections aquired by patients in hospitals like MRSA

30
Q

How can we reduce healthcare-associated infections?

A

Iscolation of patients
Screen new patients
Hygiene measures
Controlling the use of antibiotics

A Level Biology: Topic 6 (Edexcel) (5 decks)

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