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Microbiology > Bacteria Growth And Physiology > Flashcards

Bacteria Growth And Physiology Flashcards

1
Q

What is growth and what doesn’t contribute to growth

A
  • orderly increase in the sum of all components of an organism
  • not due to water uptake or lipid and saccharide deposits at membrane
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2
Q

How do bacteria multiply

What is a culture

A
  • through binary fission of a single bacteria to make up a population
  • a group of bacteria making up a population originating from a single cell
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3
Q

What is binary fission

A

-division of a single parent into 2 identical progeny with identical genetic material and you can’t differentiate between parent and progeny

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4
Q

Describe the process of binary fission

How is fission initiated

A

-fission initiated when there is an increase in cellular components until it reaches critical mass

  • DNA replicated by mitosis to produce 2 identical sets of chromosomes
  • cell elongation
  • septum forms so parent can form into daughter
  • completion of septum with distinct cell walls
  • cell separates
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5
Q

List 3 ways to grow bacteria

A

1 colonies
2 turbidity
3 biofilm formation

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6
Q

Describe colony bacterial growth

A
  • developed on solid medium

- macroscopic product of 20-30 cell divisions from a single cell

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7
Q

Describe turbidity bacteria growth

A
  • transformation of a clear broth ( liquid ) medium to a turbid suspension of 10^7-9 cells per mL
  • spectrometry used to measure number of cells in medium
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8
Q

How so biofilm formation done

A

-bacterial growth is spread thinly ( 300-400um ) over a thing inert surface

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9
Q

What does single bacteria become and what is the progeny covered in in biofilm

A

/becomes complex community of progeny covered in membrane called glycocalyx

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10
Q

What is purpose or glycocalyx in bacteria , it’s significance and how to bacteria communicate in biofilm

A

-protects community of progeny from the environment

/through complex telecommunication system called quorum sensing

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11
Q

List and describe the steps in biofilm formation

A

1 planktonic phase
-cells mobile and still coming together

2 irreversible attachment sessile state
-become fixed on one place at surface and form colonies and glycocalyx layer

3 growth and microcolony formation
-continued growth and glycocalyx formation

4 maturation
-reached full state

5 dispersed
-colony cells leaves culture and find new surface attach to

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12
Q

List infections associated with biofilm formation

A

1 infective endocarditis
2 streptococcus viridans on heart valve
3 pseudomonas aeruginosa lung infection
4 staphylococcus aureus on catheters

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13
Q

What type of growth is shown in fluid culture medium and how is it expressed

A
  • in fluid culture medium bacteria displays a uniform growth curve
  • expressed in log numbers of viable bacteria over time
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14
Q

How is bacteria growth determined

A

-fixed volume of liquid medium ( culture batch ) is inoculated with bacteria and number of viable cells per mL is determined periodically and plotted

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15
Q

What does growth curve show and list its 4 phases

A

-shows fundamental insight to genetics and physiology of bacteria replication

1 lag phase
2 exponential / log
3 stationary
4 death phase

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16
Q

Describe lag phase , what occurs and what determines length

A
  • part of graph is straight
  • cells still adapting to new environment
  • as they adapt enzymes and nutrients and intermediates for growth are accumulated until they reach feasible amounts
  • length of phase depends on species ability to adapt
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17
Q

Describe exponential phase , what occurs and what stops the phase

A
  • line increase exponentially
  • cells Dividing at constant rate

Phase stops if
1 one or more nutrients are depleted
2 lack of biological space
3 toxic metabolites accumulate and Inhibit growth

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18
Q

Describe stationary phase , what occurs

A
  • line is straight
  • growth slows down and reaches max and stabilizes
  • production of secondary metabolites occur such as spores and antibiotics
  • spores genes activated
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19
Q

Describe death phase , what occurs

A
  • line drops exponential
  • irreversible loss of ability to reproduce
  • viable cells population decrease exponentially
  • release of spores and toxins and cells are autolyzed
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20
Q

Significance of growth curve

A
  • helps to know which phase produces antibiotics

- used to explain what is happening in body during infection

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21
Q

Describe long and short exponential growths and bacteria associated

A

1 short

  • small # of bacteria initiate deadly disease as they can proliferate fast
  • symptoms are acute

2 long
-slow division leading to chronic infection eg tuberculosis bacillus

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22
Q

Describe what happens to bacteria inside body tissue

A
  • bacteria stressed
  • populations rarely fully viable
  • may cease growth but continued synthesis to adapt to stress
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23
Q

Effects of non growing bacteria

A
  • immunologic
  • sporulation and toxin release
  • production of spores and toxins
24
Q

What does bacteria need energy for

A

1 establish proton motive force - potential energy derived from
Passage of protons across a membrane

2 allow macromolecule synthesis

25
Q

List 3 mechanisms to generate metabolic energy

A

1 fermentation
2 photosynthesis
3 respiration

26
Q

Describe fermentation

A

-enzymatic process in which pyrophosphate bond is donated to ADP by a phosphorylated metabolic intermediate

27
Q

How are metabolic intermediates for fermentation formed and characteristics

A
  • metabolic rearrangement of a fermentable substrate such as glucose or lactose
  • elemental composition of fermentation product identical to those of substrate
28
Q

Example of fermentation pathway

A

-fermentation of glucose using Embden-Meyerhof pathway yielding ATP and lactic acid

29
Q

What is respiration

List alternate oxidants

A

Chemical reduction of oxidant ( 02 electron acceptor ) through a series of specific electron carriers in membrane to establish a proton motive force across membrane

-CO2, sulfate or nitrate

30
Q

Two types of electron donors and example

A

1 inorganic ( lactic acid )

2 organic ( H2 )

31
Q

Describe photosynthesis

A

-cells with pigment called chlorophyll trap sunlight and use the energy to photochemically create reductant and oxidant to produce O2 and organic matter

32
Q

Categorize microbes based on energy source

A

1 phototrophs- use light to drive metabolic processes

2 chemotrophs - use organic or inorganic elements

3 lithotrophs - inorganic only

4 organotrophs / chemoorganotrophs - organic only

33
Q

List groups of elements, the types and functions

A

Synthesis of structural components
/ C, N , O , P , S and H
-synthesis of lipids, proteins, carbohydrates and nucleic acids

Other cellular functions

  • K : actives enzymes / maintain osmolality
  • Ca2 and Mg : cofactor
  • Fe : electron transfer during redox reactions

Trace elements
-Cu , Zn , Mn : activates and stabilizers of various enzymes

34
Q

Categorize microbes based on carbon source and reductant method of C

A

1 autotrophs : do not need Organic nutrients for growth
-use photosynthesis to reduce CO2 and water expense

2 chemolitrotrophs : use inorganic substrates as reductant ( H2 or thiosulfate ) and CO2 as carbon source

3 heterotrophs : organic C which can be assimilated eg glucose

35
Q

Importance or nitrogen and it’s dry mass , it’s % in air and stability

A
  • mass nucleic acids , proteins
  • 5%
  • 80% in atomosphere
  • highly stable due to N-N triple bond
36
Q

How do all microbes assimilate N2

A

-pathways has end product as NH3

37
Q

Categorize microbes based on N2 assimilation and explain

A

1 nitrogen fixation - directly break N2 and is assimilated as NH3

2 ammonification- deaminates aas such as glutamine and glutamate to acquire NH3

3 assimilatory nitrate / nitrite reduction - reduction of nitrate / nitrite to NH3

38
Q

Importance of sulphur and can it be used in element form

A

-cellular function, cell wall , structure of coenzymes

/no

39
Q

How does microbes assimilate sulfur

A

1 autotrophic oxidize sulfur to sulfate

2 most reduce S to H2S ( salmonella )

3 some assimilate H2S from growth medium

40
Q

Use of phosphate and how assimilated

A
  • make nucleic acids , ATP and coenzymes such as NAD and NADP
  • make techoic acid and some capsular polysaccharides are phosphorylated

-assimilated always as free inorganic phosphate

41
Q

How are trace elements provided and how is Fe taken up , what are siderophores and role of plasmid derived siderophores

A
  • Tap water or contaminates of other medium ingredients
  • Fe taken and forms insoluble hydroxides at neutral pH facilitated by siderophores
  • siderophores are compounds that chelate iron and promote its transport as a soluble complex
  • major role in invasiveness of some pathogens
42
Q

What are growth factors and how obtained

A

-organic compounds needed for growth but cells can’t make them on eir own

/obtain from environment

43
Q

List environmental factors taken into bacterial growth account

A

/pH

  • temperature
  • aeration
44
Q

How do microbes regulate internal pH

A

-pumping Protons into and out of cell

45
Q

Classify microbes based on pH tolerance and put ranges

A

1 alkaliphiles
-regulate internal 9.5 over external of 9-11

2 neutrophiles
-maintains internal of 7.5 over external of 5.5-8.5

3 acidophiles
-maintain internal of 6.5 over external of 1-5

46
Q

Describe temp against growth graph

A
  • lowest temp that will not support growth but won’t kill bacteria
  • growth increases exponentially as temp increases
  • reach optimum , highest rate of growth
  • beyond optimum rate decrease fast
  • highest temp recorded that wont support growth but won’t kill
  • beyond cell is disintegrated
47
Q

Categorize microbes based on temp and put ranges and short description

A

1 psychrophile

  • range -5 to 15
  • found at arctic and Antarctica

2 psychrotrophs

  • range 20-30 but can also grow at as low as -5
  • important in food spillages eg listeria monocytogenes

3 mesophile

  • range 30-37
  • body temp optimal for mesophiles

4 thermophiles

  • range 50-60
  • not found in people as body temp to low
  • found in hot springs

5 hyperthermophiles

  • range well above boiling point
  • exist at higher pressure under water volcanoes
48
Q

How do microbes tolerate upper end range of temp and describe

A
  • heat shock response

- transient synthesis of HSP to stabilize heat sensitive proteins and deals with denatured ones

49
Q

What is sterilization with heat and cold shock phenomena

A

/use of excessive heat to kill microbes

/killing of microbes by rapid cooling

50
Q

What is aeration and how do all organism depend on it

By product of aerobic metabolism and dangers of it

A
  • atmosphere condition
  • all organisms use oxidation to transfer energy to compounds that participate in their biochemical processes
  • Peroxide and superoxide
  • Fe can generate OH radical wc can damage any biological macromolecules
51
Q

How does bacteria protect against aerobic by products and describe how they do it

A

1 superoxide dismutase
-catalyze superoxide( 02-) and hydrogen reaction to form oxygen and water

2 catalyse
-catalyze peroxide breakdown to water and oxygen

52
Q

Categorize microbes based on aeration and presence of enzymes and test tube location

A

1 obligate aerobes
-both enzymes present ,require O2 for growth and close to surface of tube

2 obligate anaerobes
-no enzyme , require complete absence of 02 and bottom of tube

3 aerotolerant anaerobes
-superoxide dismutase only , do need O2 but can grow in it and scattered all over tube

4 facultative anaerobes
-both enzymes present , can grow with or without O2 and scattered all over

5 micro anaerobes
-small amount of enzyme , require minimal amounts of O2 ( 2-10%) any more is inhibitory and found in middle of tube just under surface

6 capnophiles

  • require increased CO2 to grown
  • eg Neisseria species
53
Q

How do microbes tolerate change in external osmolality and ionic conc

A
  • uptake of K ions

- opening and closing ion and anion voltage gates

54
Q

Categorize Microbes based on salt needs and explain briefly

A

1 nonhalophile
-growth dependent on no or little salt.

2 halotolerant
-will grow in absence of presence of not extreme levels salt

3 halophile
-needs high conc of salt to grow properly

4 extend halophile
-needs excessive amounts of salt to grow properly

55
Q

What is an osmophile

A

-bacteria which requires high conc of sugar in environments to grow

56
Q

List the important human pathogen optimum conditions

A

1 mesophile temp
2 pH 7.4-7.6 ( neutrophile )
3 heterotrophs
4 mostly facultative anaerobes ( or any O2 requirement )

Microbiology (5 decks)

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