Microbial Nutrition and Growth Flashcards
Lectures 16-17
What are macronutrients? How much of the dry weight of the cell do they make up?
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
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?
Proteins are made of: Carbon Hydrogen Oxygen Nitrogen Sulpher They are 50% of the cells dry weight
Lipids are made up of fatty acid and glycerol. What are the nutrients that make up lipids? What is an example of a lipid?
Lipids are made of: Carbon Hydrogen Oxygen Phosphorus Ex) Phospholipids
Carbohydrates are made up of sugars. What are the nutrients that make up carbs? What is an example of a carbohydrate?
Carbohydrates are made of: Carbon Hydrogen Oxygen Nitrogen Ex) Polysaccharides and Peptidoglycan
Nucleic Acids are made up of nucleotides. What nutrients make up nucleic acids? What is an example of a nucleic acid?
Nucleic Acids are made of: Carbon Hydrogen Oxygen Nitrogen Phosphorus Ex) DNA and RNA
Other macronutrients include Potassium, Magnesium, Calcium and Iron. What sub-category would these elements fall under?
Inorganic Ions
What is the function of inorganic ions?
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
What are micronutrients? What is their function?
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
What element is required to make the unusual amino acid selenocysteine?
Selenium
What is a growth factor? What happens if an organism cannot synthesize a growth factor?
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.
What are the three classes of growth factors? What are their characteristics?
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+
What is an example of an organism that has no growth factor requirements?
E. coli
What can the addition of a growth factor to a medium do to an organism?
Promote growth
What is a bacteria that requires many growth factors?
Leuconostoc mesenteroides requires all 20 amino acids, 4 purines and pyrimidines, 10 different vitamins.
Which element(s) are found in no specific nutrient and are found in water and other organic media compenents.
Hydrogen and Oxygen
What element is usually presented as a phosphate salt (PO4)^3-?
Phosphorus
Why is phosphorus usually presented as a salt? Give an example.
Phosphorus is usually acquired as (PO4)^3- in the environment, and in freshwater systems (PO4)^3-is often limiting.
Ex) K2HPO4 and KH2PO4
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.
Limiting nutrient
Which element can be found as both inorganic and organic, and even in the atmosphere?
Nitrogen
Where is inorganic nitrogen found? What must happen to it before it can be used?
Inorganic nitrogen is found as salts (ex. KNO3 or NH4Cl) It must be reduced to NH3– it is used to make amino acids (-NH2).
Where is organic nitrogen found?
Organic nitrogen is provided as N rich organic molecules (ex. Amino acids or short peptides) and does not need to be reduced.
What must happen to atmospheric nitrogen before it can be used? What is the problem with using atmospheric nitrogen?
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.
True or False: Only some bacteria and archaea can use atmospheric nitrogen.
True
Which element can found only organically and in-organically?
Sulpher
