BIOLOGY 2EE3 Lecture Notes - Lecture 6: Psychrophile, Pyrimidine Dimer, Electromagnetic Radiation
23 Jun 2018
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Chapter 6
What do microorganisms need to grow?
Source for C, N, P, S
Micronutrients and metal ions
Phototroph VS Auxotroph
Phototroph - synthesize all their cellular components from basic nutrients - glucose, ammonia, etc.
- they grow in a mineral salts medium with a carbon source
Auxotroph. - need supplements in order to grow. Eg. vitamin, amino acids, purine, pyrimidine, etc.
Source of Energy for Chemotroph VS Phototroph
Chemotroph - energy from oxidization of reduced organic or inorganic compounds
Phototrophs - energy from light.
Source of Election
Organotroph - electrons form organic molecules (glucose)
Lithotrophs - electrons from inorganic sources (H2, NH4, H2S)
Source of carbon in Autotroph VS Heterotroph
Autotroph - carbon from inorganic sources
Heterotroph - carbon in preexisting organic forms
Humans are chemoorgoanoheterotroph
Nitrogen metabolism (from Chapter 13):
Ammonia assimilation - Two different systems incorporate
ammonia into amino acids: GS-GOGAT works best at low ammonium
concentrations. GDH(glutamate dehydrogenase) works best at high
ammonium concentrations.
Biosynthesis of cellular
components
Amino acid synthesis–
Main pathways give the
initial carbon skeleton of
amino acids.–
Glutamine/glutamate
donate amino groups for
other amino acids.
Effects of Oxygen on microbial growth
Aerobes grow in presence of oxygen, they require it.
Anaerobic growth occurs without oxygen. If it is present they can not grow
Microaerophles - grow best when less than normal oxygen present
Aerotolerant anerobes - don’t require oxygen but aren’t harmed by it.
Facultative anerobes can use oxygen but can also grow without it
Effects of pH on microbial growth
pH affects macromolecule structures and transmembrane electrochemical gradients
Each microbes has an optimal pH for growth
Acidophile - <5.5
Neutrophile - 5.5 to 8.5
Alkalophiles - >8.5
Effects of osmotic pressure and water availability on microbial growth
Different oslute concentrations can cause influx/efflux from cell aka swell or shrink
Water must be available for biochemical reactions.
Effects of temperature on microbial growth
Temperature affects macromolecule structures, membrane, fluidity and enzyme functions.
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Document Summary
Phototroph - synthesize all their cellular components from basic nutrients - glucose, ammonia, etc. They grow in a mineral salts medium with a carbon source. Chemotroph - energy from oxidization of reduced organic or inorganic compounds. Organotroph - electrons form organic molecules (glucose) Lithotrophs - electrons from inorganic sources (h2, nh4, h2s) Heterotroph - carbon in preexisting organic forms. Ammonia assimilation - two different systems incorporate ammonia into amino acids: gs-gogat works best at low ammonium concentrations. Gdh(glutamate dehydrogenase) works best at high ammonium concentrations. Main pathways give the initial carbon skeleton of amino acids. Glutamine/glutamate donate amino groups for other amino acids. Aerobes grow in presence of oxygen, they require it. If it is present they can not grow. Microaerophles - grow best when less than normal oxygen present. Aerotolerant anerobes - don"t require oxygen but aren"t harmed by it. Facultative anerobes can use oxygen but can also grow without it.
