L4 Flashcards
(24 cards)
What are the two main functions of nutrients in microorganisms?
- Building blocks for cell components (proteins, nucleic acids, etc.)
- Supply energy for cellular processes.
What is anabolism in microbial nutrition?
Biosynthesis of cell constituents from simpler molecules, usually requiring energy.
What is catabolism in microbial nutrition?
Breakdown of complex molecules to produce energy.
What are the basic components required in a growth medium for microorganisms?
Water, carbon source, nitrogen source, phosphorus, sulphur, inorganic salts, trace elements, and energy source.
What is the difference between autotrophs and heterotrophs?
Autotrophs use CO2 as carbon source, heterotrophs use organic molecules.
List the four nutritional categories of microorganisms.
Photoautotrophs, Photoheterotrophs, Chemoautotrophs, Chemoheterotrophs.
What is a defined medium?
Media with known quantities of pure chemicals.
What is a complex medium?
Media made from natural sources with unknown composition, like yeast extract or blood.
How do chemoautotrophs generate energy?
From redox reactions using inorganic compounds.
Why is microbial nutrition important for environmental and industrial processes?
Microbes drive element cycling, bioleaching, bioremediation, and biotechnology.
What structure allows bacterial motility?
Flagella composed of flagellin, powered by a rotary motor.
What are the different bacterial flagella arrangements?
Monotrichous=polar, Amphitrichous=single flagella on each side , Lophotrichous= tuft, Peritrichous=around.
What is the function of chemotaxis?
Allows bacteria to move toward attractants or away from repellents.
What is the ‘run and tumble’ behavior in peritrichous bacteria?
Run: anticlockwise rotation (forward); Tumble: clockwise rotation (change direction).
How does motility aid bacterial pathogenesis?
Enhances survival, nutrient access, and host colonization.
What is quorum sensing?
A communication method where bacteria sense cell density via autoinducers to coordinate behavior.
What is a biofilm?
A surface-attached microbial community encased in a gelatinous matrix.
What are the differences between prokaryotic and eukaryotic flagella?
Prokaryotic flagella rotate; Eukaryotic flagella have a 9+2 microtubule structure and whip-like motion.
What are the four protozoan motility types?
Amoeboid (pseudopodia), Cilia, Flagella, Non-motile (sporozoans).
What are magnetosomes?
Magnetic particles in some bacteria allowing orientation along Earth’s magnetic field.
when does max specific growth occur
exponential phase
describe liquid and solid media
Liquid media: easiest to prepare and use.
*Good for growing large quantities of microbes
needed for analysis or experiments.
*Not useful for separating microbes.
Solid media: made by adding agar, a
seaweed extract, to appropriate liquid. 1.5% w/v
agar is standard for plates. Agar is solid at 40oC.
direction of motility
direct= looking for movement- use phase contrast microscope + motility medium
indirect = looking for flagella - stains add extra with
cilla vs Flagella
cillia= short, 100s per cell, 3d move, fast and eukaryotes
flagella= long, 1-8 per cell, wave/whip, slow E+P
