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MICROBIO Lecture > Lecture 7 Microbial Growth > Flashcards

Lecture 7 Microbial Growth Flashcards

1
Q

Solutes such as salts and sugars ____ the availability of water to microbes.

A

Decrease

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2
Q

Availability of ___ affects growth of all cells.

This is expressed as?

A

Water

water activity (Aw)
ex.) higher [solute] ---> lower Aw
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3
Q

Hypotonic Solution

A

Solute conc. inside (intracellular) > Solute conc. outside (extracellular)

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4
Q

Isotonic Solution

A

Solute conc. inside (intracellular) = Solute conc. outside (extracellular)

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5
Q

Hypertonic Solution

A

Solute conc. inside (intracellular) < Solute conc. outside (extracellular)

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6
Q

What is a Halophile?

Name the two examples from lecture.

A

Osmophiles that live in high[Salt]

ex. ) - Halobacterium (member of the archaea)
- Staphylococcus
- Human skin
- Mannitol Salt Agar used to isolate

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7
Q

What are microbes that can grown under pH of 0-6?

A

Acidophiles

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8
Q

What are microbes that can grow under pH of 8-12

A

Alkaliphiles

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9
Q

What is the pH range of Escherichia coli?

A

pH 2-9 10million fold difference

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10
Q

How do Halophiles live in a high salt environment?

A

They use compatible solutes like KCl. Keeps intracellular solute conc. high with out interfering with growth or metabolism.

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11
Q

What are nutrients?

A

Substances used in biosynthesis and energy release - required for growth.

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12
Q

What is 95% of the microbial cell weight made of?

A

Macronutrients (or macroelemets)

C,O,H,N,S,P,Fe

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13
Q

What is the the other 5% of the cell weight made of?

A

Micronutrients (or trace elements)

Co, Cu, Zn, Mn

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14
Q

What is the form of nitrogen that microbes can use?

A

Ammonia (NH3) or Nitrate (NO3)

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15
Q

What is Nitrogen fixation?

A

N2 reduced to ammonia (NH3)

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16
Q

Rhizobium and Azotobacter

A

Rhizobium - in symbiosis with plants

Azotobacter - free living in soil

17
Q

How does food for microbes enter the cell?

A
  • at high rates
  • across membranes
  • selective fashion
  • often against concentration gradient

Passive and Active transport systems used.

18
Q

Describes Passive Transport

A
  • no energy required

- requires gradient from [higher] to [lower]

19
Q

Passive Diffusion

A

Only small molecules and certain gases

20
Q

Facilitated Diffusion

A
  • Uses membrane carrier proteins

ex) Aquaporins - form H2O channels

21
Q

Active Transport

A
  • Energy - dependent
  • Moves nutrients against gradient
  • ATP or proton motive force used
22
Q

Describe Primary Active Transport : ABC Transporters

A
  1. ) After binding solute, the solute-binding protein approaches ABC transporter.
  2. ) Solute-binding protein attaches to transporter and releases solute. Energy released by hydrolysis of ATP drives movement of solute across membrane.
23
Q

different types of ABC Transporters

A
  • Uptake ABC - move nutrients in
  • Export ABC - also called Multidrug Efflux Pumps, moves substances out
  • In bacterial cells - move antibiotics out, bacteria become resistant to antibiotic
  • In cancer cells - move anticancer drugs out, tumor becomes resistant
24
Q

Describe Secondary Active Transport and name the example from lecture.

A
  • Uses potential energy of ion gradients
  • Electron transport across membrane generates proton (H+) gradient
  • Can use gradient to do work !

Example Lac Permease
- Membrane protein, moves lactose in powered by proton also moving in

25
Q

Active Transport : Group Translocation and name the example from lecture.

A
  • Nutrient chemically altered
  • Energy from phosphoenolpyruvate attaches P to sugars
  • Phosphoenolpyruvate - key intermediate in Glycolysis
  • Metabolic pathway that converts glucose to pyruvate

REVIEW FIG. 3.14

26
Q

Describe Iron Uptake

A
  • Microbes release siderophores to acquire Fr
27
Q

What are Siderophores and name the example from lecture

A
  • Fe complex then transported into cell often using ABC

Enterobactin : An Escherichia coli siderophore

28
Q

Describe Siderophore-iron complex transport into a gram - negative bacterial cell.

A
  1. ) E. coli synthesizes and secretes an iron-binding enterochelin that bind Fe3+
    2a. ) The complex is transported to the periplasm through an outer membrane protein (FepA) and is transported into the cell by an ABC transporter that includes a periplasmic solute-binding protein (FepB) and the integral membrane proteins FepC, G, and D.
  2. ) Inside the cell, the iron is released and reduced to Fe2+
29
Q

What is Metabolism

A

All the chemical reactions in a cell

30
Q

What Catabolism

A

Breakdown of complex molecules into smaller ones with release of benefit for Anabolism - reactions that build cells.

MICROBIO Lecture (9 decks)

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