MBIO 1010 Study Guide - Final Guide: Anabolism, Ultra-High-Temperature Processing, Mycobacterium Tuberculosis
31 May 2018
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UNIT 3 – MICROBIAL GROWTH AND NUTRITION
Cell Chemistry and Nutrition
1. Macronutrients
o Elements required in large amounts to build macromolecules
§ The building blocks of cell material
o The big 6 macromolecules,
§ C, H, O, N, P, and S (CHONPS)
§ Makes up >90% of dry weight of the cell
2. Protein
o Polymer made of building blocks (amino acids)
§ C, H, O, N, and S (no P)
§ Makes up >50% of cell dry weight
3. Lipids
o Building blocks are fatty acids and glycerol
§ C, H, O, and P (no N, and S)
§ Ex. Phospholipids
4. Carbohydrates
o Building blocks are sugars
§ C, H, O, and N (no P, and S)
§ Ex. Polysaccharides and Peptidoglycan
o Nucleic Acids Building blocks are nucleotides
§ C, H, O, N, and P (no S)
§ Ex. DNA and RNA
5. Other Macronutrients (Inorganic Ions)
o Often serve as metabolic co-factors
§ Non-protein component required for
enzyme function
§ K, Mg, Ca, and Fe
o Mg2+ helps stabilize membranes and nucleic acids
o Ca2+ helps stabilize cell walls, and plays a role in heat stability of endospores
10 Macronutrients
§ C HOPKNS CaFe Mg
• Acronym for remembering the 10 macronutrients
• Of the macronutrients we usually do not worry about H and O because
of those are the components of water
• Ca and Fe are also not as important
§ All of the macronutrients should be considered when making media
6. Micronutrients
o Elements required in very small amounts (trace metals)
o Usually serve as cofactors for enzymes
§ Ex. Mn, Zn, Co, Ni, Cu, and Mo
o Se is required to make the unusual amino acid selenocysteine
7. Growth Factors
o Small organic molecules required for the growth of some organisms
§ Those that do not have the metabolic ability to make the substance themselves
§ Must be added to medium to grow that microbe in the lab
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a. Amino acids
§ 20 amino acids are needed for protein synthesis
• 8 amino acids are essential and are known as growth factors
b. Purines and Pyrimidines
§ A, G, T, C, and U
§ Needed to make nucleotides, building blocks of DNA and RNA
c. Vitamins
§ Small molecules used to make organic cofactors
§ Non-protein components required by some enzymes
• Ex. Nicotinic acid ® NAD+
§ All cells need a wide variety of vitamins
• Some cells can make these vitamins on their own
• Other cells prefer the vitamins to be fed to them
o Many bacteria have no growth factor requirements
§ Addition of growth factors to medium may promotes growth factor
• Ex. E. coli
Ø Can make all of its nutrients from scratch as long as it has the
10 macronutrients
o Some bacteria require
§ Requires all 20 amino acids, 4 purines and pyrimidines, 10 different vitamins
• Ex. Leuconostoc mesenteroides
Ø Growing L. me requires a lot of growth factor requirements
Nutrient Sources
- Usually identified by element
1. Hydrogen
o No specific nutrient
o Found in H2O and organic media components
2. Phosphate
o Usually provided as phosphate salt (PO43-)
§ Ex. K2HPO4, KH2PO4
§ Reason: usually acquired as PO43- in the environment
§ In freshwater systems PO43- is often the limiting nutrient source
Limiting nutrient
§ In relatively low concentration compared to other nutrients
§ When it runs out, growth stops despite another nutrients present
§ Outbreaks in lakes can be explained through providing the population with the
limiting nutrient allowing for bacteria or other microorganisms to start appearing
3. Nitrogen
o Many possible sources
o Ordered below from the most to the least difficult way to acquire nitrogen
a. Atmospheric N2
§ N2 is reduced to 2NH3 (Nitrogen fixation
§ NH3 is used to make amino acids
§ Energetically expensive
§ Can only be done by some Bacteria and Archaea, not possible by Eukaryotes
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b. Inorganic N
§ Provided as salts
• Ex. KNO3 or NH4Cl
§ Must be reduced to NH3 which is used to make amino acids (-NH2)
§ Adding KNO3 will require your culture to work harder to change the KNO3 into an
NH2 form for amino acids
c. Organic N
§ Provided as N rich organic molecules
§ Does not have to be reduced
§ Ex. Amino acids or short peptides
4. Sulfur
a. Inorganic S
§ Provided as salts
§ Must be reduced to the level of S2- which is used to make amino acids
• Assimilative sulfate reduction
§ Must be modified before it can be used
• Ex. MgSO4
b. Organic S
§ Pre-made amino acids
§ Less energy to assimilate
• Ex. Cysteine and methionine
5. Carbon
o Refers to the source the majority of C in macromolecules
o Organisms placed into 2 groups based on how they obtain C
a. Heterotrophs
§ Use organic carbon
§ One or more C is reduced
§ Organic carbon is any carbon that has one or more hydrogens attached to it
• Ex. Organic acids, alcohols, carbohydrates, amino acids
• CO2 is not an organic carbon source
b. Autotrophs
§ Use inorganic carbon (CO2) as their sole source of carbon
§ Cells that do not need to use pre-existing carbon
§ Requires energy to assimilate
• Photosynthesis
• Ex. Anabaena
Nutrient Transport
1. Facilitated Diffusion
o Involves integral membranes proteins that allow specific molecules to diffuse across the
cytoplasmic membrane
o Forms a channel for diffusion
o Follows the usual rules of diffusion
§ Solutes move from an area of high concentration to low concentration
§ No extra energy is required
o Simply speeds up the rate of diffusion for molecules that would not easily cross the
membrane otherwise
Document Summary
Cell chemistry and nutrition: macronutrients, elements required in large amounts to build macromolecules. The building blocks of cell material: the big 6 macromolecules, C, h, o, n, p, and s (chonps) Makes up >90% of dry weight of the cell: protein, polymer made of building blocks (amino acids) C, h, o, n, and s (no p) Makes up >50% of cell dry weight: lipids, building blocks are fatty acids and glycerol. C, h, o, and p (no n, and s) C, h, o, and n (no p, and s) Polysaccharides and peptidoglycan: nucleic acids building blocks are nucleotides. C, h, o, n, and p (no s) Dna and rna: other macronutrients (inorganic ions, often serve as metabolic co-factors. K, mg, ca, and fe: mg2+ helps stabilize membranes and nucleic acids, ca2+ helps stabilize cell walls, and plays a role in heat stability of endospores.
