Module 13 Flashcards
What are physical parameters that control growth? How does each physical parameter inhibit growth?
Temperature-denature the enzymes and proteins when too high; affects membrane fluidity; slows down enzyme activity when too cool
pH-proteins and enzymes denature at both; affects hydrogen bonding
Osmotic pressure-draws water out retarding growth; draws water in and cells swell and possibly burst
Describe the categories for prokaryotes for temp growth
Psychrophiles-cold loving
Psychotrophs-higher optimum
mesophiles-the most numerous group with moderate temp
thermophiles-heat loving
extreme thermophiles-archaea, hot springs and deep sea thermal vents
Describe the categories for prokaryotes for pH growth
Acidophiles- 0-5.5 pH
Neutrophiles- 5.5-8.0 pH
Alkalophile- 8.0-11.5 pH
Describe the categories for prokaryotes for osmotic pressure and growth
Hypotonic- water moves into the cell
Hypertonic- food preservation- causes plasmolysis, water moves out of the cell
Isotonic- no net gain or loss of water
What is the main difference between a halotolerant (facultative halophile) bacteria and an extreme (obligate) halophile?
extreme halophile
-In archaea (domain)
-High salt only 30-40%
Facultative halophile
-In bacteria (domain)
-Grow over a huge range- up to 15%
What is plasmolysis? Under what conditions does plasmolysis occur? Why does this condition inhibit the growth of a bacterium?
The shrinkage of the protoplasm away from the cell wall
Caused by the loss of water in the cell- due to being placed in hypertonic solution, exposed to increased salinity or chemicals
draws water out of the cell retarding growth
What elements are necessary for growth?
Carbon
-Backbone of all living matter (organic life)
Nitrogen
-14% dry weight of cell (protein and nucleic acid synthesis)
Oxygen and hydrogen
-Found in all components of cell
Sulfur and phosphorus
-4% dry weight of cell (cysteine and nucleic acid synthesis)
What is a trace element? Why are trace elements important to prokaryotes?
Small amounts of minerals
Important as cofactors for enzymes
Iron, copper, zinc
What are the 5 categories bacteria are divided into based upon the effects of oxygen on their growth? Be able to explain and recognize the growth pattern of each in a test tube.
Obligate aerobe
-Grow only in the presence of O2
Obligate anaerobe
-Killed by O2
Facultative anaerobe
-Organisms grow with or without the presence of O2 but prefer it
Aerotolerant anaerobe
-Don’t use O2 for growth, and not harmed either
Microaerophile
-Less than atmospheric concentrations of O2
What is the difference between a complex media and a chemically defined media? What is a fastidious bacterium? Which media will a fastidious bacterium grow on?
Chemically
-Know the exact amounts of every substance in the media
-Fastidious bacteria grow- require several different growth factors
Complex
-Composed of extracts which vary from batch to batch
-High in amino acids, vitamins, minerals
Where do you find anaerobic bacteria? How would you grow an anaerobic bacterium?
No oxygen or low oxygen environments
-Reducing media- deplete oxygen in the media
-Anaerobic jar
-Capnophiles- like CO2 environment
How does a selective media differ from a differential media? What is an enrichment culture? When would you use any of these three types of media?
Selective media- inhibits the growth of unwanted bacteria
Differential media- different types of bacteria will appear differently on the plate
Enrichment culture- designed to increase specific bacteria
—Allows for the isolation and identification of specific microorganisms from a mixed culture
What is binary fission? What is a generation time?
Type of asexual reproduction where a parent cell divides into two identical cells.
The time required for a cell to divide
Example problem: If you start with one bacterium that has a generation time of 15 minutes, how many bacteria will you have in 2 hours?
8 GT
1-2-4-8-16-32-64-128-256
256 bacteria
What does the growth curve of a bacterium look like? What does each phase of the graph represent (what is it called)? What is occurring at each phase?
- Lag phase
-Little or no cell division
-Period of synthesis - Log phase
-Exponential growth phase
-Generation time reaches a constant
-Cells most metabolically active
-Most sensitive to antibiotics - Stationary phase
-Death=division
-Constant number of cells
-Run out of nutrients or pH changed - Death phase
-Death greater than division
-No nutrients or extreme pH
