Chapter 3 Flashcards
Metabolism
m—all biochemical reac.ons in a cell – Anabolic—energy requiring – Catabolic—energy releasing Macronutrients • Micronutrients
Nitrogen
(13%)
• NH3 commonly used as a nitrogen source
• Some can use NO3
-
• N2—nitrogen fixers
• What cellular compounds contain nitrogen?
– Amino acids, nitrogenous bases
Carbon
(50%)
• Autotrophs?
– Use CO2 as sole source of carbon, energy from
light or inorganic chemicals
• Heterotrophs?
– Requires organic carbon as sole source of carbon
• What cellular compounds contain carbon?
– Amino acids, faUy acids, organic acids, sugars,
nitrogen bases, aroma.c compounds, etc.
Other macronutrients
• Phosphorous – nucleic acids, phospholipids • Sulfur – cysteine, methionine, vitamins • Potassium – enzyme ac.vity • Magnesium – stabilizes ribosomes, membranes, nucleic acids, enzyme ac.vity • Calcium – stabiliza.on of cell walls and endospores
Micronutrients
Iron—cellular respira.on, siderophores
• Manganese—replaces iron in some microbes
• Selenium—formate dehydrogenases (NAD+
and anaerobic metabolism, cytochromes in
electron transport chain)
• Others—cofactors for enzymes
Culture Media
Nutrient solu.ons used to grow microbes • Chemically defined—known amounts of purified chemicals • Complex (undefined)—digests of animal or plant products, nutrient composi.on is unknown
Selective
contains compounds that inhibit the growth of some microbes but not others – An.bio.cs – Carbon sources – Ex: mannitol salt agar
Differential
an indicator allows for
differen.a.on of microbes as they grow
– pH indicator
– Ex: mannitol salt agar
Enriched
complex plus supplement, ex. blood
Colony
mass of cells origina.ng from a single
cell, grows on surface of medium
Laboratory culture: Agar
- Polysaccharide from red algae
- Melts at ~95°C and solidifies at ~45°C
- Solidifies culture medium
Making a streak plate to obtain pure
cultures
- Isolated colonies at end of streak
- Confluent growth at beginning of streak
Catabolic diversity
- Chemoorganotroph
- Anaerobic respiration
Chemoorganotroph
— energy obtained by
oxida.on of organic compounds
Anaerobic respira.on
electron acceptor
other than oxygen