Chapter 3 - Metabolism Flashcards
Macronutrients
nutrients needed in large amounts
Micronutrients
nutrients needed in small amounts
-trace metals and growth factors
Nutrients
supply of monomers (or precursors of) required for cell growth
Carbon
bacterial cell is ~50% carbon
heterotrophs use organic carbon
autotrophs use carbon dioxide
Nitrogen
proteins, nucleic acids
in nature: ammonia, nitrate (NO3-), nitrogen gas
nearly all microbes use ammonia
Phosphorus
nucleic acids and phospholipids
sulfur
sulfur-containing amino acids
- cysteine/methionine
vitamins
potassium
required for enzymes for activity
magnesium
stabilizes ribosomes, membranes, and nucleic acids
- also required for enzyme activity
calcium/sodium
required by some microbes
- marine microbes
Growth factors
organic compounds required in small amounts in some organisms
- vitamins, amino acids, purines, pyrimidine
Vitamins
most frequently required growth factor
- most function as enzymes
Active transport
accumulates solutes against concentration gradient
3 classes
- simple transport, group translocations, ABC transporter
Simple transport
driven by proton motive force
- symport/antiport
symport
solute and protons co-transported in one direction (E. coli lac permease)
antiport
solute and proton transported in opposite directions
Group translocation
- substance transported is chemically modified
- energy-rich compound drives motion (not proton motive force)
Phosphotransferase system
in E. coli
- group translocation
- transport sugars, glucose, mannose, and fructose in
ABC transport
ATP-binding cassette
high substrate affinity
requires transmembrane and ATP-hydrolyzing proteins
Gram -: periplasmic binding proteins
Gram +: substrate-binding proteins on external surface of membrane
Chemoorganotrophs
conserve energy from chemicals > organic
Chemolithotrophs
oxidize inorganic compounds (H2, H2S, NH4+)
- “sulfur” bacteria, “nitrifying” bacteria, “iron” bacteria
Phototrophs
convert light into ATP
Heterotrophs
obtain carbon from organics
Autotrophs
obtain carbon from CO2
Free energy
G - energy released that is available to do work
- change in energy during a reaction delta G
Exergonic
negative delta G
-release free energy
Endergonic
positive delta G
-acquire energy
Free energy of formation
Gf - energy released or required during formation of a molecule from its elements
A + B -> C + D
delta G = Gf(C + D) - Gf(A + B)
Activation energy
minimum energy required for molecules to become reactive
- catalyst lowers energy
Enzymes
biological catalysts
typically proteins (some RNAs)
active site : binds substrate
Prosthetic groups
tightly bound
usually bind covalently and permanently
coenzymes
loosely bound
most are derivative of vitamins
chemiosmosis theory
all living cells use a reduction potential gradient between a primary electron donor and a terminal electron acceptor to ultimately generate energy (proton motive force) for phosphorylation reactions (ATP synthesis)
reduction potential
tendency to donate electrons
- more negative E’ donates to more positive E’
Oxygen (redox)
strongest significant natural electron acceptor
Long-term energy storage in prokaryotes
glycogen, poly-beta-hydroxybutyrate, elemental sulfur
Long-term energy storage in eukaryotes
starch, lipids
Fermentation
anaerobic catabolism in which organic compounds donate and accept electrons
Respiration
aerobic or anaerobic catabolism in which a donor is oxidized with O2 (aerobic) or other compounds (anaerobic) as an electron acceptor
