September 16 Flashcards
Gliding motility
Does not use flagella
Smooth and slower than flagella
Requires contact with a surface
Excrete polysaccharide slime (can glide on agar)
Some cyanobacteria
Microbial Taxis Types
Directed movement in response to a stimulus
- Chemotaxis: movement in response to a chemical
- Phototaxis: movement in response to light
- Aerotaxis
- Hydrotaxis:
Describe E. coli’s taxis
“run and tumbe”
Peritrichous flagellar arrangement
Attractants sensed by chemoreceptors on cell
Define metabolism
All biochemical reactions in a cell
Catabolic
breaks down larger molecules into smaller molecules, exogonic
Anabolic
Smaller molecules are built into larger ones, endogonic
Macronutrients
Nutrients needed in large amounts
Ex. Carbon
Micronutrients
required in small amounts
Ex. iron
Why do cells need nitrogen?
Growth-limiting
required for proteins, nucleic acids
Why do cells need phosphorus?
Nucleic acids and phospholipids
Why do cells need sulfur?
Some amino acids contain sulfur
Also in vitamins
Why do cells need potassium?
Some enzymes require K+
Why do cells need magnesium?
Stabilizes cell membrane, ribosomes, nucleic acids
Why do cells need calcium?
Stabilizes cell walls, Ca2+ heat stability of endospore
Why do cells need iron?
It plays a role in e- transport
Affect of temperature on enzymatic activity
In most chemical reactions the rate of reaction tends to increase with an increase in temperature.
In enzymatic reactiions, temperatures above optimal cause denaturation
Affects of pH on Enzymes
Denaturation occurs above and below optimal pH
Affects of Substrate Concentration on Enzyme Activity
Saturation point: all enzymes are bound to substrate, activity levels off
