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Microbiology > Ch.6 > Flashcards

Ch.6 Flashcards

1
Q

Mesophiles

A
  • Moderate temperature loving microbes

* Most pathogen’s belong to this group

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2
Q

Thermophiles

A

Heat loving microbes

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3
Q

Most bacteria grow best in this pH range

A

6.5-7.5

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4
Q

Mold and yeast grow best at this pH range

A

5.0-6.0

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5
Q

Osmotic Pressure

A
  • Microorganisms require 80-90% water for growth.

* Many foods are preserved with salt, the salt draws water out of their cells and prevents growth.

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6
Q

Hypertonic

A

Cell is in a solution whose concentration of solute is higher than in the cell, The cellular water passes out through the plasma membrane to high solute concentration.

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7
Q

Plasmolysis

A

Shrinkage of the cell cytoplasm

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8
Q

Obligate Aerobes

A

Organisms that requires oxygen (O2) to live.

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9
Q

Facultative Anaerobe

A

Both aerobic and anaerobic growth.

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10
Q

Obligate Anaerobe

A

Organism that does not use oxygen (O2) to live.

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11
Q

Chemical requirements for microbial growth:

A

Carbon, Nitrogen, Sulfur Phosphorus, Trace Elements (Small mineral requirements)

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12
Q

Major physical requirements:

A

Temperature
pH
Osmotic Pressure

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13
Q

Quorum sensing

A

Cell-to-cell communication, bacteria coordinate their activity
Attracts other microbes to Biofilm

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14
Q

Planktonic form of biofilm

A
  • Free swimming bacterium attaches to a surface.
  • Form pillar like structures with channels between them so water can flow through, the water carries nutrients and takes away waste.
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15
Q

Chemically Defined

A
  • Exact chemical composition is known
  • Must contain organic growth factors that serve as a source of carbon and energy
  • e. Coli
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16
Q

Complex medium

A
  • Medium in which the exact chemical composition not know.
  • Growth of most chemoheterotrophic organisms.
  • consist of tone, beef extract, sodium chloride, agar, and water
17
Q

Nutrient Broth

A
  • Complex medium made beef extract and peptone.

* In liquid form

18
Q

When agar is added to the broth it becomes:

A
  • Nutrient Agar

* Agar itself is not a nutrient

19
Q

Differential

A
  • A solid culture medium that makes it easier to distinguish colonies of the desired organisms from other colonies growing on the same plate.
  • Ex: Blood Agar
20
Q

Selective Medium

A
  • Cultural medium designed to suppress the growth of unwanted bacteria and encourage the growth of the desired microbes.
  • Mannitol Salt Agar
21
Q

Quadrant Streak Plate Method

A
  • Isolation method to obtain a pure culture.
  • Grows into isolated communities and then maybe transferred to a test tube of nutrient medium to form a pure culture containing only one type of bacterium.
22
Q

Agar comes from?

A

Brown seaweed

23
Q

Bacterial growth Curve

A
  • Increase in bacterial numbers

* 4 phases

24
Q

Lag Phase

A
  • Last one hour to several days, period of little or no cell division
  • Not dormant, metabolic activity, synthesis of enzymes and molecules.
  • Intense activity preparation for population growth.
25
Q

Log Phase (Exponential Growth Phase)

A
  • Cells begin to divide and enter a period of growth

* Reproduction is most active by binary fission (bacteria) or mitosis (yeast),

26
Q

Stationary Phase

A

Period of equilibrium, microbial deaths balance production of new cells.

27
Q

Death Phase

A
  • Population decreasing at a logarithmic rate.
  • Cells are swimming in their own waist and have nothing to eat
  • Number of deaths exceeds the number of new cells formed.
28
Q

Budding

A
  • Few species reproduce this way.
  • They form a small initial outgrowth, that enlarges until it’s size approaches that of the parent cell, and then it separates.
29
Q
  • The time required for a sale to divide in the population to double.
  • The population doubles with each generation.
A
  • Generation time (doubling time)

* Ex.: 2^4= 16 cells

30
Q

Psychrophiles/Psychrotrophs

A
  • Cold loving microbes.

* Food microbiologists favor

Microbiology (19 decks)

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