Microbial diversity

Question 1

energy to build cells comes from chemical reactions, explain

Answer 1

• catabolic rxns/ catabolism = breakdown of complex molecules into smaller ones releasing energy
• anabolism = reactions that build molecules, require energy

*catabolism provides energy from anabolism

cellular metabolism = catabolic + anabolic processes

• not all energy releaed by catabolic rxns can be harnessed, some released as heat

Question 2

organisms can be described by how they obtain their _____

Answer 2

Carbon

• AUTOtroph: CO2
• HETEROtroph: preformed organic compounds

Energy source

• PHOTO: light photons
• CHEMOLITHOtroph: energy from minerals
• CHEMOORGANOtroph: energy from organic comp

Question 3

what is the primary energy storage currency in cells

Answer 3

• ATP
• under physiological conditions,ATP always forms a complex w magnesium

(one reasion ehy magnesium is an essential nutrient of all living things

Question 4

what are teh central reactions for ATP generations in chemoorganoheterotrophs

Answer 4

• glycolysis, krebs cycle and oxidative phosphorylation to generate ATP
• glucose into polysaccharides (requires energy)

Question 5

what are energy carriers in cells besides ATP

Answer 5

• GTP (guanosine triphosphate) provides energy for protein synthesis
• other energy carriers also carry electrons, NADH, FADH

*transfer of electrons from donor to acceptor releases energy

Question 6

what is NADH

Answer 6

•Nicotinamide adenine dinucleotide (NADH) carries two or three times as much energy as ATP.

• It also donates and accepts electrons.
• NADH is the reduced form (electron donor), NAD+ is the oxidized form (electron acceptor).

*Overall oxidation of NADH exergonic reaction

NADH + H+ + ½ O2 → NAD+ + H2O DGo’ = -52.6 KJ/mol

• releases energy (exergonic reaction), can be harnessed

•Overall reduction of NAD+

NAD+ + 2H+ + 2e– → NADH + H+ DGo’ = 62 KJ/mol

•Reaction requires energy input (endergonic rection)

*also used in reactions that build biomass

Question 7

What is FADH

Answer 7

•Flavine adenine dinucleotide (FAD) is another related coenzyme that can transfer electrons.

• FADH2: reduced form
• FAD: oxidized form

•- carries less energy than NADH

FAD + 2e- + 2H+ —–> FADH2

Question 8

what different things can chemoorganotrophs use for energy

Answer 8

• complex and simple glycans
• lipids broken into glycerol and fatty acids

aromatics into simpler comp

• proteins broken down into amino acids
• all feed into central pathways of catabolism: glycolysis, TCA these paths then erve to breakdown organic mol to release energy

Question 9

What is embden-myerhodd parnas?

Answer 9

• also called glycolysis
• found in many prokaryotes, all animals and plats
• two major phases
• Activation phase: 2 atp mol to phosphorylate glycose forming fructose 1,6 bisphosphate - this is broken down into 2 glyceraldehyde 3 phosphate mol
• Energy payoff phase: harnesses the energy in the G3P mol, producing four ATP mol, two NADH and teo pyruvates
• generation of ATP directly from catabolic pathways = substratelevel phosphorylation
  note: ATP gen from high energy intermediates and not using ETC

Question 10

describe fermentation

Answer 10

• allows the oxidation of NADH to NAD without the use of ETC

*imp bc some bacteria dont have ETS

• in some bacteria the electron acceptor is pyruvate or another organic compound
• bacteria without these systems rely on fermentation

Question 11

where did the eukaryotic mitochonria and chloroplast arise from?

Answer 11

mitochonrdia from endosymbiosis of aerobic respiratory bacteria (gram-neg)

chloroplast from a photosynthetic cyanobacterium

*energy-gnerating ocmponents of these organelles are in the cytoplasmic membrane of prokaryotes fo the inner membrane of the organelles in eukaryotes

Question 12

describe the proton motive force

Answer 12

ETC contains: alternative arrangement of proton + electron carriers (NADH oxidoreductase) and electron only carriers (cytochromes)

• H+ is pumped out across the CM and E goes to next component on ETC
• the transfer of H+ through proton pump generates an electrochemical gradient of protons (proton motive force)
• PMF composed of a transmembrane ph difference.gradient and electric potential (charge difference across the membrane)
• PMF drives conversion of ADP to ATP through ATP synthase

*gradeint is dissipated as protons flow back trhough ATP synthase

*known as chemiosmotic theory/hypothesis

Question 13

what is ATP synthase

Answer 13

• PMF drives ATP synthase via membrane embedded ATP synthase
• also called F1FoATP synthase (F1F0 refers to the two domains)
• is a complex integral membrane protein through which H+ flows down an electrochemical gradient, providing the energy for ATP production by oxidative phosphorylation.
• Besides ATP synthesis, the Proton gradient drives many cellular functions, e.g. flagella rotation, efflux of toxic antimicrobials, uptake of nutrients

Question 14

describe oxidative phosphorylation/respiration

Answer 14

• involves the etc- oxidation of an electron donor, reduction of a ifnal electron acceptor, generation of PMF and coupling of energy released from proton gradeint to phosphorylate ADP
• when final acceptor is oxygen = aerobic, when anything else (usually Nitrate) is anerobic
• some bacteria have both

Question 15

describe the forms of nitrogen, assimilation and dissimilation metabolisms

Answer 15

• respiration using oxidized forms of nitrogen is widespread among bacteria, archaea, some fungi and yeast
• reduction of oxidized states of nitrogen for energy yeild is called dissimilatory denitrification
• assimilatory nitrogrna metabolism - incorporation of nitrogen into organic molecules

*nitrogen can be assimilated into biomolecules or broken donw (dissimilated) to return to environment

*no one species that can take nitrate to nitrogen gas, diff bacteria do diff steps

Question 16

what are the 3 major classes of prokaryotic energy generating metabolisms that use an ETS

Answer 16

1. Organotrophy (or chemoorganotrophy):
   * organic electron donors, inorganic or organic terminal electron acceptors
2. Lithotrophy (or chemolithotrophy): noly prokaryotes
   * inorganic electron donors (e.g. H2S), inorganic (e.g. NO3- ,O2 ) or organic terminal acceptors
3. Phototrophy:
   * involves light energy capture by chlorophyll, obtaining electrons from inorganic compounds (e.g. H2S or H2O) or organic molecules & generating a PMF ^is water used its oxygenic photosynthesis