Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbiology > Microbe-Environment Interactions > Flashcards

Microbe-Environment Interactions Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What are extremophiles?

A

Species which can survives under extreme conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How are microbes classified?

A

By temperature
By pH
By growth in salt
By effect of oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is minimum growth temperature?

A

The lowest temperature a species will grow at

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is maximum growth temperature?

A

The highest temperature at which growth is possible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is optimum growth temperature?

A

The temperature at which the species grows best

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens to growth rate above optimum growth temperature and why?

A

It declines rapidly because higher temperatures denature enzymes required for growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are organisms pH range?

A

2-3 units

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What type of pathogens can tolerate low pH’s? Give an example.

A

Enteric pathogens

E.coli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are neutrophils optimum growth pH?

A

5.5-8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What pH is referred to as optimum pH?

A

External pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What pH must internal cells be maintained at?

A

pH 5-9

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How much salt is in sea water?

A

3%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Requirement for salt is absolute. What does absolute mean?

A

It cannot be replaced by other ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are non-halophiles?

A

Microbes that do not grow well in salty conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are halophiles?

A

Microbes that can tolerate salty conditions to a certain extent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are moderate halophiles?

A

Microbes that grow well in salty conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are extreme halophiles?

A

Microbes that thrive in salty conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are obligate aerobes?

A

Microbes that require oxygen to survive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are obligate anaerobes?

A

Microbes that are harmed by oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are facultative anaerobes?

A

Microbes that use oxygen when it is present but can grow without it

  • Fermentation
  • Anaerobic respiration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are microaerophilic microbes?

A

Those which require oxygen but at lower levels than atmospheric oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are aerotolerant microbes?

A

Those which can not use oxygen for growth but are unaffected by its presence
- Respire anaerobically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

When are superoxide free radicals produced?

A

During aerobic respiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why are superoxide free radicals toxic?

A

Because they are chemically unstable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How do organisms that grow in atmospheric oxygen cope with toxic superoxide free radicals?

A 
Superoxide dismutase (SOD) neutralises O2- 
Catalase converts toxic H2O2 to H2O
26
Q

What environmental factors influence microbial growth?

A 
Carbon sources
Oxygen 
Temperature 
pH
Salinity 
Water availability 
Sunlight (UV radiation)
Predation
27
Q

What are the problems surrounding microbial survival in high temperatures?

A

Proteins denature
Small molecules are unstable
DNA helix unwinds at high temperatures
Membrane become more fluid

28
Q

How might protein structure change in order to increase thermodynamic stability?

A

Proteins may fold differently

29
Q

What property of amino acids lowers their tendency to unfold?

A

Hydrophobic core

30
Q

What type of proteins might cells contain in order to protect themselves from high temperature?

A

Heat shock proteins

- Refold denatured proteins

31
Q

What do cells contain that help DNA to remain coiled and functional in high temperatures?

A

Enzymes and DNA repair proteins
- Reverse DNA gyrase
Histone-like proteins and additional DNA binding proteins

32
Q

Name a solute found in the cytoplasm that prevents unwinding and chemical damage of DNA.

A

Di-glycerol phosphate

33
Q

How might membranes change in order to reduce fluidity?

A

More saturated and longer fatty acid chains

- These molecules pack more tightly making the membrane more stable

34
Q

What do archaeal cell membranes lack?

A

Lipids

35
Q

What are the problems surrounding microbial survival in low temperatures?

A

Decreased enzymatic activity
Lower metabolic activity
Slow rates of ion transport and diffusion

36
Q

How might membranes change at low temperatures?

A

Increased unsaturated and shorted chain length fatty acids = more fluid
Increased proportion of cyclic fatty acids

37
Q

What types of proteins are produced at low temperatures? Give three examples

A 
Cold shock proteins
- RecA = involved in DNA repair 
- Hsc66 = maintains protein conformation 
- CspA = transcriptional factor 
Antifreeze proteins
38
Q

What is the main problem surrounding microbial survival at low pH?

A

Maintaining pH homeostasis inside cells (pH 5-7)

39
Q

What are aminophospholipids are how might they be affected at low pH?

A

Increased number

- They make membranes more positively charged

40
Q

How are proton pumps affected at low pH?

A

Activated

41
Q

How does membrane permeability to protons change at low pH?

A

Less permeable

- H+ influx inhibited by positive membrane potential

42
Q

How is the number of membrane channels affected at low pH?

A

Reduced size and number of membrane channels

43
Q

What cytoplasmic buffering molecules are produced at low pH?

A

Sugars

Amino acid derivatives

44
Q

What is the main problem surrounding microbial survival at high salt concentrations?

A

Osmoregulation = maintaining turgor pressure inside cells

45
Q

How does the cell protect proteins and enzymes at high salt concentrations?

A

Accumulation of K+ instead of Na+

46
Q

Why is salt excluded from the cytoplasm at high salt concentrations and what is it replaced with?

A

Replaced with organic compatible solutes which do not interfere with enzymatic function

47
Q

What is the main problem surrounding microbial survival at low water contents?

A

Desiccation = water loss

48
Q

What do cells produced at low water contents?

A 
Extracellular matrix (capsule)
Osmoprotectants = trehalose 
More DNA repair proteins
49
Q

What are xerophiles?

A

Organisms that are adapted to live in environments with low water activity

50
Q

How can the growth of pathogens be controlled artificially?

A

By altering their certain aspects of their environment;

  • Heat
  • Cold
  • Acidity
  • Water activity
  • Chemicals
51
Q

How is pathogen growth altered by heat?

A

Heat kills microbes by denaturing proteins and enzymes

Heat preserved canned goods are a good method of food preservation

52
Q

What are the different ways in which heat can be altered in a pathogens environment?

A 
Moist heat 
- Boiling - Steaming 
Pasteurisation
Dry heat
- Flaming - Sterilisation
53
Q

How is pathogen growth altered by cold?

A

Microbes can be killed when ice crystals disrupt their cell membrane
Usually cold temperatures slow or stop microbial growth

54
Q

What microbe is the exception and is not affected by cold temperatures?

A

Listeria monocytogenes

  • Food borne bacterial pathogen
  • Can grow at 4 degrees
55
Q

What temperature are microbes preserved at in labs?

A

-80 degrees with glycerol which acts as a cryptoprotectant

56
Q

How is pathogen growth altered by acidity?

A

Foods often have a high or low pH in order to limit microbial growth
Provides a way of preserving food

57
Q

How is pathogen growth altered by water activity?

A

High water activity within foods leads to more rapid rancidity
Lowering water activity is a way of preserving foods
- Drying
- Concentrating
- Adding salt or sugar

58
Q

How is pathogen growth altered by chemicals?

A

Antimicrobials
Sterilants
Disinfectants

59
Q

What are antimicrobial agents?

A

Natural or synthetic chemicals that kill or inhibit growth of microbes

  • cidal = kill microbes
  • static = inhibit microbial growth
60
Q

What are sterilants?

A

Destroy all forms of microbial life

61
Q

What are disinfectants?

A

Kill microbial cells but do not always inactivate spores

Microbiology (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions