BIOL 220 Lecture Notes - Lecture 3: Chemostat, Pep Group Translocation, Starvation Response

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21 Jun 2018

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Lecture 3

BIO 220

Microbial Culture and Development

Environmental Influences and Control of Microbial Growth

Uptake of Nutrients

oGroup translocation is a process that uses energy to chemically alter the substrate

during its transport

oThe phosphotransferase system is an example present in all bacteria

It uses energy from PEP to attach a phosphate to specific sugars

The system has a modular design that accommodate different substrates

Siderophores

oSpecialized molecules secreted to bind ferric ion and transport into the cell

oIron is the released into the cell once taken up

oAre often specific to species that makes them biochemical warfare for resources

What do we grow microbes in

oSolid/agar medium

Useful for trying to isolate a pure colony

oLiquid/broth medium

Useful for studying metabolic and other characteristics of pure culture

Common Method of Plating

oDilution streaking

Dragging a loop across the surface of an agar plate

oSpread plate

Tenfold dilutions are performed on a liquid culture

A small amount of each dilution is then plated

CFU

oColony forming units

oRepresents culturable viable cells in a sample. There is some uncertainty around

whether the colony was formed by a single cell or a group of cells

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Document Summary

Uptake of nutrients: group translocation is a process that uses energy to chemically alter the substrate during its transport, the phosphotransferase system is an example present in all bacteria. It uses energy from pep to attach a phosphate to specific sugars. What do we grow microbes in: solid/agar medium. Useful for trying to isolate a pure colony: liquid/broth medium. Useful for studying metabolic and other characteristics of pure culture. Dragging a loop across the surface of an agar plate: spread plate. Tenfold dilutions are performed on a liquid culture. A small amount of each dilution is then plated. Cfu: colony forming units, represents culturable viable cells in a sample. There is some uncertainty around whether the colony was formed by a single cell or a group of cells: a viable plate count determines the number of living cells in terms of cfu/unit of measure. Are nutrient rich but poorly defined: synthetic media.

Related Questions

Question 1

A microorganism's ability to use a harmful pesticide as a source of carbon and energy is an example of

Select one:

a. chemoautotrophy

b. nitrogen fixation

c. bioremediation

d. photoautotrophy

e. biosynthesis

Question 2

Autotrophs and heterotrophs differ in

Select one:

a. their ability to utilize CO2 as a sole carbon source.

b. their ability to incorporate CO2 into cells.

c. only a few enzymes.

d. their ability to synthesize precursor molecules.

e. their ability to utilize CO2 as a sole energy source.

Question 3

If the amino acid valine constituted approximately 4% of the total cell protein of a bacterium, how much valine should be added to a defined medium in order to grow 1 gram of this organism?

Select one:

a. 0.2 mg

b. 2 mg

c. 20 mg

d. 40 mg

e. 200 mg

Question 4

Transport of HPO₄ along with a proton (H⁺) is an example of

Select one:

a. antiport

b. uniport

c. facilitated diffusion

d. symport

e. group translocation

Question 5

The energy required for transport via ABC transporters is derived from

Select one:

a. a proton gradient

b. an electrical charge separation across the membrane

c. ATP hydrolysis

d. a symport mechanism

e. a high energy phosphate bond of PEP

Question 6

The spread plate method would clearly be preferred over the pour plate method when isolating colonies of

Select one:

a. anaerobic bacteria

b. thermophilic bacteria

c. bacteria from temperate lake zones

d. purple non-sulfur bacteria

e. agar-degrading bacteria

Question 7

Enrichment culture procedures for many microorganisms require intial growth in liquid media, followed by growth on solid media. The solid media is used to

Select one:

a. provide proper growth conditions.

b. isolate single colonies of the microbes.

c. get rid of competing microorganisms.

d. isolate strict aerobes.

e. enrich for specific nutrients.

Question 8

The optical density of light scattered by bacteria is a very useful tool for estimating population size. What can alter the bacteria's light-scattering properties?

Select one:

a. Cell volume depending on its growth stage

b. The condition of being absent of microorganisms.

c. The amount of light projected from the room.

d. The standard curve

e. Standard deviation from growth curve.

Question 9

What is true about a bacterial colony?

Select one:

a. It arises from an individual cell and represents an isolate strain.

b. Colonies, and CFU (colony forming units) on streak plates represent a diverse microbial culture.

c. In order to obtain a colony, on must perform cloning steps.

d. Axenic cultures to not represent CFUs or colonies.

e. Colonies require differential media in order to separate them from the population.

Question 10

What is a biofilm?

Select one:

a. All cells in a population achieve a steady state

b. A specialized, surface-attached, collaborative community of bacteria

c. A complex media made of the chemical building blocks that a cell needs

d. A type of anaerobic growth chamber.

e. A type of spore

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BIOL 220 Lecture Notes - Lecture 3: Chemostat, Pep Group Translocation, Starvation Response

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