Exam 1 Lecture 8 Flashcards
(18 cards)
How is prokaryotic growth defined?
An increase in cell numbers= increase in biomass
What is needed for cell growth?
Energy and nutrients
Macronutrients and Micronutrients
Good environment
Macronutrient examples?
C, O, N, H, P, S
Cations- MG++, Fe++, Ca++, K+, Na+
Micronutrient Examples?
Mn, Zn, Co, Mo, Ni, Cu and other vitamins and cofactors
How do they measure bacterial growth?
Direct cell counting
Can put a measured amount of suspension media on a plate and count colonies
Or monitoring turbidity
Turbidity is a measure of the degree to which the water loses its transparency due to the presence of suspended particulates.
Name the 4 bacterial growth phases?
- Lag (no growth adjusting to the new environment for a short time)
- Log (exponential- plenty of nutrients)
- Stationary (Nutrients running low)
- Death (no nutrients left in media)
Gene expression is adjusted according to stage
5 environmental factors that affect cell growth?
Temperature (covered later)
pH (alkaliphile, neutralophile, and acidophile)
Osmolarity (salt usually) (halophile and halotolerant)
Oxygen (Covered later)
Pressure (barophile, barotolerant)
4 different groups of bacteria that tolerate different temperatures and their temp ranges?
- Psychrophile (10-20 C)
- Mesophile (15-45 C)
- Thermophile (50-80 C) Only Prok and Arch over 65 C
- Extreme Thermophile (65-90 C) Only Arch over 90 C
In a test tube what are the different layers of O2 availability?
High at top - Aerobic
Low in middle - microaerophilic
No at bottom- Anaerobic
Types of O2 tolerant bacteria?
- Obligate aerobe
- Microaerophiles
- Facultative microbes/anaerobes also know has aerotolerant anaerobes
- Obligate anaerobes
A big example of well known facultative(either low or high O2) microbe?
E. Coli -glycolysis or fermentation
E coli doubling time in O2 rich media and O2 minimal media?
20 mins versus 60 mins
What passes freely through membranes?
Only uncharged non-polar- H2O, O2, NH3, CO2, H2
The rest need transport systems
How do symporters work?
Two molecules move in the same direction, one going along its gradients take another with it against its gradient
PMF -LacY- H+ and lactose in E coli
Not always PMF
How do antiporters work?
While one molecule moves down its gradient and another is passed against its gradient in opposite direction.
Example in E coli H+and tetracycline
How do ABC transporters work?
Use ATP hydrolysis inside a cell on the transporter to power it.
Often use solute binding or escort proteins (siderophores) to bring the solute/nutrient needed to the transporter for transport into the cell
Used for sugars and amino acids or iron
Example- E coli maltose transporter
How do PTS (Group translocation/phosphotransferase systems work?
Use PEP to add phosphate to sugars or other modifications to substrate during transport across the membrane into the cell
E coli and glucose to glucose-6-phosphate setting it up for glycolysis
Do cells produce all types of transporter all the time?
No- depends on the environment
