Chapter 3 - Microbial Growth and Nutrition Flashcards Preview

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Flashcards in Chapter 3 - Microbial Growth and Nutrition Deck (46)
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1
Q

Macronutrients

A

Elements required in large amounts to build macromolecules - C, H, O, N, P and S makeup >90% of the dry of the cell

2
Q

Protein

A

C, H, O, N (and S)
Polymer made of building blocks - amino acids
- >50% of cell dry weight

3
Q

Lipids

A

C, H, O (and P)
Building blocks = fatty acids and glycerol
ex. Phospholipids

4
Q

Carbohydrates

A

C, H, O, (and N)
Building blocks = sugars
ex. polysaccharides and peptidoglycan

5
Q

Nucleic acid

A

C, H, O, N, P
Building blocks = nucleotides
ex. DNA and RNA

6
Q

Other macronutrients

A
Inorganic ions (K, Mg, Ca, Fe)
Often serve as metabolic co-factors
7
Q

Metabolic co-factors

A

Non-protein component required for enzyme function

8
Q

Enzymes involved in protein synthesis require

A

K+

9
Q

Cytochrome require

A

Fe2+

10
Q

Mg2+ help

A

Stabilize membranes and nucleic acids

11
Q

Ca2+ helps

A

Stabilize cell walls and plays a role in heat stability of endospores

12
Q

Micronutrients

A

Elements required in very small amounts (trace elements)

Usually serve as cofactors

13
Q

Se is required to make

A

Unusual amino acid selenocysteine

14
Q

Growth factors

A

Small organic molecules required for growth

15
Q

Classes of growth factors

A

Amino acids, purines and pyrimidines, and vitamins

16
Q

How many acids are required for protein synthesis?

A

20 amino acids

17
Q

Purines and pyrimidines

A

A, G, T, C, and U

Needed to make nucleotides, building blocks of DNA and RNA

18
Q

Vitamins

A

Small molecules used to make organic cofactors

Non-protein components required by some enzymes

19
Q

Growth factor requirements

A

Many have no growth factors - E. coli

Some bacteria require many - leuconostoc mesenteroides

20
Q

H and O

A

No specific nutrient

Found in H2O and organic media components

21
Q

P

A

Usually provided as phosphate salt PO4^3- acquired from the environment
In freshwater systems, it is often limiting

22
Q

Limiting nutrient

A

When it runs out, growth stops despite other nutrients present

23
Q

Inorganic N

A

Provided as salts

Must be reduced to NH3 - used to make amino acids (-NH2)

24
Q

Organic N

A

Provided as N rich organic molecules (amino acids or short peptides) - does not need to be reduced

25
Q

Atmospheric N2

A

N2 is reduced to 2NH3 - nitrogen fixation
NH3 is used to make amino acids
Energetically expensive
Only done by some bacteria and archaea

26
Q

Inorganic S

A

Provided as salts

Must be reduced to the level of S^2- to make amino acids - assimilative sulfate reduction

27
Q

Organic S

A

Pre-made amino acids (cysteine and methionine)

Less energy to assimilate

28
Q

Heterotrophs

A

Use organic carbon

One or more C is reduced

29
Q

Autotrophs

A

Use inorganic carbon (CO2) as their sole source of carbon

Requires energy to assimilate - photosynthesis

30
Q

Defined medium

A

Exact chemical composition is known

31
Q

Minimal medium

A

A defined medium that provides the minimum nutritional requirements for growth (no growth factors)

32
Q

Complex medium

A

Exact chemical composition is not known
Often made from meat or yeast extracts
Supply a variety of growth factors
ex. T-soy broth and plates

33
Q

Differential medium

A

Allows different bacteria to be distinguished

34
Q

Blood agar

A
T-soy plate + 5% sheep's blood
Allows differentiation of hemolytic bacteria
alpha - incomplete destruction
beta - complete destruction
gamma - no destruction
35
Q

Selective medium

A

Contain ingredients that inhibit the growth of unwanted microbes

36
Q

Mannitol salt agar

A

Contains very high salt - only halotolerant bacteria will grow
Used to isolate staphylococci from skin

37
Q

Enriched medium

A

Supplemented with special nutrients to encourage the growth of fastidious bacteria
Complex nutrient requirements - require many growth factors

38
Q

Metabolism

A

The sum total of all of the chemical reactions that occur in a cell

39
Q

Catabolic reactions (catabolism)

A

Energy-releasing metabolic reactions (e.g. fermentation, respiration)

40
Q

Anabolic reactions (anabolism)

A

Energy-requiring metabolic reactions (biosynthesis)

41
Q

Chemorganotrophs get their energy from

A

chemical reactions involving organic material

42
Q

Chemolithorophs get their energy from

A

inorganic chemical reactions

43
Q

Phototrophs

A

Energy from light

44
Q

Heterotrophs carbon source

A

Organic carbon

45
Q

Autotrophs carbon source

A

CO2

46
Q

What is a defined medium useful for?

A

Studying metabolism