Typed lecture notes covering chapter 4 of Microbiology: An Evolving Science, the textbook used in the "General Microbiology" course (BioM122) at UCI. Aligns with lecture 4.
• Macronutrients: major elements in cell macromolecules and cations necessary for protein function.
• Micronutrients: trace elements necessary for enzyme function.
• Autotrophs: fix CO2 and assemble into organic molecules. Ex. Photoautotrophs, Chemiolithoautotrophs
• Heterotrophs: used pre-formed organic molecules and assemble them into new organic molecules. Ex. Photoheterotrophs,
Chemoheterotrophs/organotrophs
○ Receive their energy from breaking down complex organic molecules.
• Phototrophs: obtain energy from chemical rxns triggered by/that absorb light.
• Chemotrophs: obtain energy from oxidation-reduction source; does NOT absorb light.
• Lithotrophs: use inorganic molecules to donate electrons.
• Organotrophs: use organic molecules to donate electrons.
• Nitrogen fixers: possess nitrogenase, which converts N2 to ammonium ions (NH4+).
○ May be free-living in soil or water, or they may form symbiotic associations w/ plants. Ex. Rhizobium are symbionts in
leguminous plants.
• Nitrifiers: oxidize ammonia to nitrate (NO3-).
• Denitrifiers: convert nitrate to N2. Ex. Anaerobic bacteria in the lungs use nitrate as an alt e- acceptor to oxygen.
• Selectively permeability in membrane:
○ Permeases: substrate-specific carrier proteins.
○ Dedicated nutrient-binding proteins that patrol the periplasmic space.
○ Membrane-spanning protein channels/pores
• Facilitated diffusion: passive transport; molecules are moving down their conc gradient. NO energy used!
• Active transport: uses energy b/c molecules are moving against their conc gradient.
○ In symport, molecules travel in the same direction.
○ In antiport, molecules are actively transported in the opposite direction. Uses ATP.
• ABC transporters: largest family of energy-driven transport systems.
○ Uptake ABC transporters: essential for transporting nutrients.
○ Efflux ABC transporters: used as multidrug efflux pumps.
• Siderophores: specialized molecules secreted to bind ferric ion (Fe3+) and transport it into the cell. Iron is released into the
cytoplasm and reduced to the more useful ferrous form (Fe2+).
• Group translocation: uses energy to chemically alter the substance during its transport. Changes chemical composition of a
molecule so that conc gradient doesn't matter.
○ Phosphotransferase system (PTS): present in all bacteria. Uses energy from PEP to attach a phosphate to specific sugars.
• Bacteria are grown in culture media, in either:
○ Liquid/broth: useful for studying pure cultures.
○ Solid (agar gel): useful for separating mixed cultures.
• Pure colonies are isolated in 2 main techniques:
○ Dilution streaking: a loop is dragged across the surface of an agar plate. Goal is to isolate cells so that one can start a
colony.
○ Spread plate: tenfold serial dilutions are performed on a liquid culture. A small amt of each dilution is plated.
○ Absorbance measurement of optical density: shines light thru liquid culture to quantify cells present.
• Types of media:
○ Complex media: nutrient-rich but poorly defined.
○ Minimal defined media: contain solely essential growth nutrients.
• All components and concentrations known.
○ Enriched media: complex media where specific-blood components are added.
○ *Selective media: favor growth of one organism over another.
○ *Differential media: exploit differences b/w 2 species that grow equally well.
• Different microbes have specificity of conditions (ie growth factors) they need in order to grow in a laboratory media.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller PrinceAlixD. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $2.99. You're not tied to anything after your purchase.
