Chapter 3 - Microbial Growth and Nutrition Flashcards Preview

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

Macronutrients

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

2

Protein

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

3

Lipids

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

4

Carbohydrates

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

5

Nucleic acid

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

6

Other macronutrients

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

7

Metabolic co-factors

Non-protein component required for enzyme function

8

Enzymes involved in protein synthesis require

K+

9

Cytochrome require

Fe2+

10

Mg2+ help

Stabilize membranes and nucleic acids

11

Ca2+ helps

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

12

Micronutrients

Elements required in very small amounts (trace elements)
Usually serve as cofactors

13

Se is required to make

Unusual amino acid selenocysteine

14

Growth factors

Small organic molecules required for growth

15

Classes of growth factors

Amino acids, purines and pyrimidines, and vitamins

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How many acids are required for protein synthesis?

20 amino acids

17

Purines and pyrimidines

A, G, T, C, and U
Needed to make nucleotides, building blocks of DNA and RNA

18

Vitamins

Small molecules used to make organic cofactors
Non-protein components required by some enzymes

19

Growth factor requirements

Many have no growth factors - E. coli
Some bacteria require many - leuconostoc mesenteroides

20

H and O

No specific nutrient
Found in H2O and organic media components

21

P

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

22

Limiting nutrient

When it runs out, growth stops despite other nutrients present

23

Inorganic N

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

24

Organic N

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

25

Atmospheric N2

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

26

Inorganic S

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

27

Organic S

Pre-made amino acids (cysteine and methionine)
Less energy to assimilate

28

Heterotrophs

Use organic carbon
One or more C is reduced

29

Autotrophs

Use inorganic carbon (CO2) as their sole source of carbon
Requires energy to assimilate - photosynthesis

30

Defined medium

Exact chemical composition is known

31

Minimal medium

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

32

Complex medium

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

Differential medium

Allows different bacteria to be distinguished

34

Blood agar

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

35

Selective medium

Contain ingredients that inhibit the growth of unwanted microbes

36

Mannitol salt agar

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

37

Enriched medium

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

38

Metabolism

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

39

Catabolic reactions (catabolism)

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

40

Anabolic reactions (anabolism)

Energy-requiring metabolic reactions (biosynthesis)

41

Chemorganotrophs get their energy from

chemical reactions involving organic material

42

Chemolithorophs get their energy from

inorganic chemical reactions

43

Phototrophs

Energy from light

44

Heterotrophs carbon source

Organic carbon

45

Autotrophs carbon source

CO2

46

What is a defined medium useful for?

Studying metabolism