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MBIO 1010 > Microbial Nutrition and Growth > Flashcards

Microbial Nutrition and Growth Flashcards

Lectures 16-17

1
Q

What are macronutrients? How much of the dry weight of the cell do they make up?

A 
Macronutrients are the building blocks of the cell, and are required in large amounts. The nutrients include:
Carbon
Hydrogen
Oxygen
Nitrogen 
Phosphorus
Sulpher 
They make up 90% of the cells dry weight
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2
Q

Proteins are made up of amino acids. What are the nutrients that make up protein and how much of the dry weight of the cell do they make up?

A 
Proteins are made of: 
Carbon
Hydrogen
Oxygen
Nitrogen
Sulpher
They are 50% of the cells dry weight
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3
Q

Lipids are made up of fatty acid and glycerol. What are the nutrients that make up lipids? What is an example of a lipid?

A 
Lipids are made of:
Carbon
Hydrogen
Oxygen
Phosphorus 
Ex) Phospholipids
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4
Q

Carbohydrates are made up of sugars. What are the nutrients that make up carbs? What is an example of a carbohydrate?

A 
Carbohydrates are made of: 
Carbon
Hydrogen
Oxygen
Nitrogen 
Ex) Polysaccharides and Peptidoglycan
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5
Q

Nucleic Acids are made up of nucleotides. What nutrients make up nucleic acids? What is an example of a nucleic acid?

A 
Nucleic Acids are made of: 
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus 
Ex) DNA and RNA
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6
Q

Other macronutrients include Potassium, Magnesium, Calcium and Iron. What sub-category would these elements fall under?

A

Inorganic Ions

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7
Q

What is the function of inorganic ions?

A

Often serve as metabolic co-factors
Non-protein component required for enzyme function
Enzymes involved in protein synthesis require K+
Cytochromes (e-carriers) require Fe2+
Mg2+ helps stabilize membranes and nucleic acids Ca2+ helps stabilize cell walls, and plays a role in heat stability of endospores

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8
Q

What are micronutrients? What is their function?

A 
Micronutrients are nutrients required in very small amounts. The nutrients include: 
Manganese
Zinc
Cobalt
Nickel
Copper 
Molybdenum
These usually serve as co-factors for enzymes
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9
Q

What element is required to make the unusual amino acid selenocysteine?

A

Selenium

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10
Q

What is a growth factor? What happens if an organism cannot synthesize a growth factor?

A

A growth factor is a small organic molecule required for growth. If an organism cannot synthesize it, in a lab it must be added to the organisms media.

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11
Q

What are the three classes of growth factors? What are their characteristics?

A

Amino acids
-20 amino acids are needed for protein synthesis
Purines and pyrimidines
-A, G, T, C and U
-Needed to make nucleotides, building blocks of DNA and RNA
Vitamins
-Small molecules used to make organic cofactors
-Non-protein components required by some enzyme
-Ex) Nicotinic acid -> NAD+

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12
Q

What is an example of an organism that has no growth factor requirements?

A

E. coli

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13
Q

What can the addition of a growth factor to a medium do to an organism?

A

Promote growth

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14
Q

What is a bacteria that requires many growth factors?

A

Leuconostoc mesenteroides requires all 20 amino acids, 4 purines and pyrimidines, 10 different vitamins.

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15
Q

Which element(s) are found in no specific nutrient and are found in water and other organic media compenents.

A

Hydrogen and Oxygen

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16
Q

What element is usually presented as a phosphate salt (PO4)^3-?

A

Phosphorus

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17
Q

Why is phosphorus usually presented as a salt? Give an example.

A

Phosphorus is usually acquired as (PO4)^3- in the environment, and in freshwater systems (PO4)^3-is often limiting.
Ex) K2HPO4 and KH2PO4

18
Q

What is the term that describes a nutrient in relatively low concentration compared to other nutrients, and when it runs out, growth stops despite other nutrients present.

A

Limiting nutrient

19
Q

Which element can be found as both inorganic and organic, and even in the atmosphere?

A

Nitrogen

20
Q

Where is inorganic nitrogen found? What must happen to it before it can be used?

A

Inorganic nitrogen is found as salts (ex. KNO3 or NH4Cl) It must be reduced to NH3– it is used to make amino acids (-NH2).

21
Q

Where is organic nitrogen found?

A

Organic nitrogen is provided as N rich organic molecules (ex. Amino acids or short peptides) and does not need to be reduced.

22
Q

What must happen to atmospheric nitrogen before it can be used? What is the problem with using atmospheric nitrogen?

A

Atmospheric nitrogen (N2) first has to be reduced to 2NH3 for Nitrogen fixation. NH3 is used to make amino acids. The downside of using atmospheric nitrogen is it is energetically expensive.

23
Q

True or False: Only some bacteria and archaea can use atmospheric nitrogen.

A

True

24
Q

Which element can found only organically and in-organically?

A

Sulpher

25
Q

Where is in-organic sulpher found? What must happen to it before it is used? What is this process called?

A

In-organic sulpher is provided as salts (ex. MgSO4). It must be reduced to the level of S2 to make to make amino acids- this is called Assimilative sulfate reduction

26
Q

Where is organic sulpher found? What is a upside to using it?

A

Organic sulpher is a pre-made amino acids (cysteine and methionine). It takes less energy to assimilate.

27
Q

Which element is the source to the majority of macromolecules?

A

Carbon

28
Q

What groups are organisms placed in depending on how they obtain carbon?

A

Heterotroph and autotroph

29
Q

What is a heterotroph? What are some examples?

A

Uses organic carbon
One or more C is reduced (ie. a C atom with one or more H’s)
Examples are: organic acids, alcohols, carbohydrates, amino acids

30
Q

What is an autotroph? What are some examples?

A

Uses inorganic carbon (CO2) as their sole source of carbon
It requires energy to assimilate
What it takes to use photosynthesis
Example: Anabaena

31
Q

What are the classe(s) of culture media?

A 
Defined media:
-Exact chemical composition is known 
-Useful for studying metabolism 
Minimal media:
-A defined medium that provides the minimum nutritional requirements for growth (ie. No growth factors
Complex media: 
-Exact chemical composition is not known 
-Often made from meat or yeast extracts 
-Supply a variety of growth factors
32
Q

What is a differential medium?

A

A medium used to distinguish different bacteria.

33
Q

What is an example of a differential medium? What is its composition? What does it differentiate?

A

Blood agar is a differential medium. It is made of a T-soy plate with 5% sheep’s blood. It distinguishes hemolytic bacteria and the three different types:
Alpha hemolysis- incomplete destruction of red blood cells
Beta hemolysis- complete destruction of red blood cells
Gamma hemolysis- no destruction

34
Q

What is a selective medium?

A

A selective medium contains ingredients that inhibit the growth of unwanted microbes, and allow only specific microbes to grow.

35
Q

What is an example of a selective medium? What is it made of? What does it select?

A

An example would be a mannitol salt plate. It contains very high salt, so that only halotolerant bacteria will grow. It is used to isolate staphylococci from skin.

36
Q

What is a enriched medium?

A

An enriched medium is supplemented with special nutrients to encourage the growth of fastidious (picky) bacteria. It requires man growth factors.

37
Q

What is an example of an enriched medium?

A

Chocolate agar or blood agar

38
Q

What are the energy classe(s) or microorganisms?

A

Metabolism
-The sum total of all of the chemical reactions that occur in a cell
Catabolic reactions (catabolism)
-Energy-releasing metabolic reactions (e.g. fermentation, respiration)
Anabolic reactions (anabolism)
-Energy-requiring metabolic reactions (biosynthesis)

39
Q

How are microorganisms grouped into energy classes?

A

Their source of electrons and energy.

40
Q

Which energy class gets energy from chemical reactions involving organic material?

A

Chemorganotrophs

41
Q

Which energy class gets energy from light?

A

Phototrophs

42
Q

Which energy class gets energy from reactions involving inorganic material?

A

Chemolithotrophs

MBIO 1010 (14 decks)

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