Chapter 16: Microbial life Flashcards
Prokaryotes’ contribution to life :)
- First cells were single-celled organisms with no membrane-bound organelles that existed alone 🙁 for 1.5 billion years.
- Cyanobacteria (photosynthetic) introduced oxygen into Earth’s atmosphere, which permitted diversification of life.
Define autotroph, heterotroph
Autorophs (like plants) make their own food. Heterorophs (like animals) get their foods from elsewhere.
Explain how eukaryotic life arose out of endosymbiosis
Organelles (mitochondria, chloroplasts, nuclei) were prokaryotes that were engulfed by other prokaryotes. Started to depend on one another for resources.
Explain the significance of prokaryotes to life on Earth
Maintain ecological balance:
* Live on and in humans and animals (like stomach and skin).
* Produces food and chemicals.
* Causes disease 🙁
What is microbiology
Study of microorganisms
Classify organisms based on trophy (photoautotroph, chemoautotroph, photoheterotroph, chemoheteroph).
see chart on GD
Photoautotroph
* Harness solar energy.
* Harness carbon from CO2 to build organic compounds.
Ex. cyanobacteria, plants, algae.
Chemoautotroph
* Harness chemical energy
* Harness carbon from CO2 to build organic compounds.
Ex. some archea, nitrogen-fixing bacteria.
Photoheterorophs
* Harness solar energy.
* Harness carbon from organic source.
Ex. halobacteria.
Chemoheterotroph
* Harness chemical energy.
* Harness carbon from organic source.
* Ex. common in Archaea, bacteria, protists, fungi, animals, some plants.
Classify organisms based on their oxygen requirements
Obligate aerobes: require oxygen.
Obligate anaerobes: can’t use oxygen and are poisoned by it:
* Some exclusively get energy from fermentation.
* Others perform respiration using inorganic molecule other than oxygen.
Facultative anaerobes use oxygen if available
* Can also get energy by fermentation in anaerobic environments.
Classify organisms into domains
prokaryotic: archaea, bacteria.
Eukaryotic: eukarya.
Compare and contrast bacteria and archaea
Main difference is their nucleic acid sequence (plus ribosomal RNA, cell wall structure, lipids in cell membranes).
Bacteria have peptidoglycan in their cell wall, Archaea doesn’t
Shapes of bacteria
Cocci: spherical
Bacilli: rod-shaped
Spiralli: spiral
What is gram stain
see GD
A stain that classifies bacteria by cell wall structure:
* Thick walls of peptidoglycan traps dye → stains purple (gram-positive).
* Complex walls with less peptidoglycan that don’t retain dye → stains pink (gram-negative).
Structure and function of bacterial cell wall
see GD
External to plasma membrane that protect bacteria from osmotic changes
* Have peptidoglycan (large mesh-like polymer that forms the bacterial cell wall).
Function of capsule
see GD
External of cell wall; made of sugars.
* protects bacteria from immune detection by phagocytes
* assists in adhesion to surfaces
* colony formation,
* formation of biofilm.
Biofilm, how does it form?
What does it protect from?
Forms from bacterial capsules fusing togather.
Protects bacteria from chemicals like antibiotics.
Function of flagella
se GD
Helps bacterial cell move:
* Taxis: movement towards or away from stimulus.
Function of pili
see GD
Common in gram-neg. bacteria.
* Attachment to surfaces, colonization/infection, conjugation.