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