Chapter 4 Flashcards
Binary Fission
- Chromosome begins to replicate and move to opposite ends
- Plasma membrane pinches inward and forms a protein ring
- Cytoplasm splits. New membrane made
- Two daughter cells result.
Generation TIme
Time it takes for a population to double in number.
Nt = N0 x 2^n
Cooperative interactions
Growth of one species otherwise unable to survive. Metabolic waste of one is nutrient for another.
Competitive interactions
Competition for nutrients - synthesize toxic compounds to inhibit competitors.
Biofilms
Polysaccharide encased communities. Secretion is tightly regulated. More resistant to disinfectants; pass nutrients through channels between cells.
Petri dish
Allows air. Excludes contaminants.
Agar
Solid- can be sterilized. Few microbes can degrade agar.
Factors that affect growth?
Temperature, atmospheric oxygen content, pH, water content (salt concentration), energy source, carbon source.
Neutrophile
Multiples in the range of pH 5 to 8.
How do prokaryotes deal with pH extreme environments?
Prokaryotes that live in pH extremes maintain a near-neutral internal pH by pumping protons in and out of the cell.
Acidophile
Grows optimally at pH below 5.5
Alkalophile
Grows optimally at a pH above 8.
Extremeophiles are most often…
archaea
How do prokaryotes that grow in high-solute solutions maintain water availability?
They increase the internal solute concentration of their contents.
Halotolerant
Can grow in relatively high sat solutions, up to approximately 10% NaCl.
Halophile
Requires high levels of sodium chloride to grow.
Obligate aerobe
Must have O2 to grow
Facultative anaerobe
Can grow without O2, but uses it for respiration when available
Obligate anaerobe
CANNOT grow in the presence of O2
Microaerophile
Likes a specific, low concentration of O2
Aerotolerant anaerobe
Does not have a preference for presence of O2 when growing
Components of amino acids?
C, H, O, N, sometimes S
Components of lipids
C, H, O, P
Components of nucleic acids
C, H, O, N, P
Components of sugars
C, H, O
What macros/cell components is P used to compose?
Nucleic acids, membrane lipids, and ATP
Components of enzymes
K, Mg, Ca, Fe
Photoautotrophs
Energy source: sunlight
Carbon source: CO2
Photoheterotrophs
Energy source: sunlight
Carbon source: organic compounds
Chemolithoautotrophs
Energy source: inorganic chemicals
Carbon source: CO2
Chemoorganoheterotrophs
Energy source: organics
Carbon source: organics
Autotrophs
Can fix their own inorganic CO2 into organic C forms
Heterotrophs
Can’t fix their own inorganic CO2; rely on organic C forms
Complex Media
Contains nutrient rich ingredients like meat juices and digested proteins. Variable chemical compounds.
Chemically Defined Media
Contains precise amounts of pure chemicals.
Selective Media
Inhibits growth of certain species and isolates them.
Differential Media
Changes certain species in a recognizable way
MacConkey agar has lactose and a pH indicator - lactose fermenters are pink. What is this an example of?
Differential media.
Medium and incubation conditions favor growth of one species over another. Why is this useful?
Helps narrow down a species if it isn’t present in high numbers in a mix culture.
What are the five phases of bacterial growth?
- Lag phase
- Log or exponential phase
- Stationary phase
- Death phase
- Phase of prolonged decline.
When to use membrane filtration?
For liquid cultures with relatively few cells. Cells are concentrated before they are moved to a plate.
Measuring biomass?
Turbidity is proportionate to cell concentration.
What do acid and gas producers indicate, and why is this useful?
Indicators of metabolism, i.e. living cells.
Psychrophile
Optimal growth temperature between -5 and 15 Celsius
What is thermostability a result of?
Protein structure
Psychotroph
Grows at refrigerator temperatures
Mesophile
Growths between 25 and 45 C. Humans are a good environment.
Thermophile
Optimal temperatures between 45 and 70 C
Hyperthermophile
Optimal temp of 70 C and greater
Which of the following are examples of chemotrophs?
-Algae
-Bacterial pathogens of humans
-Mammalian cells
-Photosynthetic bacteria
or
-Fungi?
Bacterial pathogens of humans
Mammalian cells
Fungi
Microbial cells must maintain near-neutral internal pH. Because of this, bacteria that grow in acidic environments have mechanisms to pump protons out that enter the cell, or bring protons into the cell?
Pump protons out of the cell
Bacteria that require growth factors are called
fastidious
True or false: biofilms are highly resistant to disinfectants when compared to their free-living counterparts.
True.
If you inoculated a test tube of cooled liquid agar with an obligate anaerobe and incubated it, where would you find growth?
Only at the bottom of the tube - obligate anaerobes can only grow when there is no presence of O2
Which of the following is a poor example of a chemoorganoheterotroph?
-Humans
-Plants
-Fungi
or
-E. coli?
Plants - plants use photosynthesis, i.e. sunlight as their source of energy
Which enzyme converts H2O2 to water and O2 during aerobic conditions?
Catalase
Which of the following statements are true? Pick more than one.
- ROS are toxic to obligate anaerobes, who lack protective functions against them.
- ROS can damage cell components.
- ROS are used by obligate anaerobes instead of O2.
- ROS are formed as byproducts of aerobic respiration.
- ROS are commonly found in anaerobic environments
- ROS are toxic to obligate anaerobes, who lack protective functions against them (such as enzymes that digest ROS).
- ROS can damage cell components.
- ROS are commonly found in anaerobic environments
Enriched media
contain the nutrients required to support the growth of a wide variety of organisms, including some fastidious ones.
If solute concentration is higher outside of the cell than it is inside of the cell, water will diffuse out due to osmosis. This will result in ____
plasmolysis
How are liquid batch cultures most often aerated to support the growth of aerobic microbes?
They are grown in tubes that are shaken continuously
How might an enrichment culture be used to isolate organisms capable of nitrogen fixation?
Using a culture that does not contain any form of nitrogen
Algae vs Fungi?
Algae are photosynthetic organisms that have chlorophyll and can make their own food. Fungi are heterotrophs, while algae are autotrophs. Fungi live in soil, air and water and can thrive both in sunlight and darkness. Some types of fungi are mushrooms, mold and yeast.
Chemolithotrophs are specific to
prokaryotes
