Metabolism

Question 1

What is the metabolic options for obtaining energy

Answer 1

chemotrophy It is receiving energy for organic or inorganic chemicals Chemoorganotrophs (glucose + O2 -> CO2 + H2O + ATP) Chemolithotrophs (H2 + O2 -> H2O + ATP) Or phototrophy phototrophs (light-> ATP)

Question 2

Whats the carbon flow and energetics for Chemoorganotrophic organic molecules

Answer 2

• carbon flow of CO2 - Biosynthesis - +O2 for Aerobic respiration - Anaerobic respiration (NO3-, SO4^2- as the electron flow) S for proton motive force to yield ATp and organic e- acceptors used.

Question 3

Anaerobic respiration

Answer 3

Similar or even same Electron Transport Chain as for aerobic respiration Need alternative electron acceptor include inorganic nitrogen and sulphur, carbon dioxide, and iron compounds

Question 4

Aerobic ETC in Ecoli

Answer 4

input are 2e- from NADH and FADH2 , O2 and 4H+ Outputs are ATP and H2O uses Complex 1, Complex II (Succinate dehydrogenase) complex III and complex IV (cytochrome C oxidase)

Question 5

Anaerobic ETC in Ecoli

Answer 5

input are 2e- from NADH and FADH2, NO3- and 2H+ Outputs are ATP NO2- and H2O uses complex 1, complex II (fumarate reductase), menaquinone, complex III and complex IV nitrate reductase

Question 6

Glycolysis

Answer 6

Two reaction series are linked to energy conservation in chemoorganotrophs - fermentation and respiration Differ in mechanism of ATP synthesis - Fermentation: substrate-level phosphorylation; ATP directly synthesized from an energy-rich intermediate - Respiration: oxidative phosphorylation; ATP produced from proton motive force formed by transport of electrons

Question 7

Chemo-organotrophy

Answer 7

Metabolism of glucose under aerobic conditions. Stage I Preparatory reactions. Stage II Making of pyruvate and synthesis of ATP by substrate level phosphorylation Stage III The fate of pyruvate

Question 8

Variations in fermentation end products

Answer 8

Question 9

The citirc acid cycle

Answer 9

•Citric acid cycle: pathway through which pyruvate is completely oxidized to CO2

–Initial steps (glucose to pyruvate) same as glycolysis

–Per glucose molecule, 6 CO2 molecules released and NADH and FADH generated

–Plays a key role in catabolism and biosynthesis

•Energetics advantage to aerobic respiration

Question 10

How much ATP is made per glucose in aerobic respiration

Answer 10

Question 11

what is the carbon flow and energetics of chemolithotophic metabolisms

Answer 11

CO2 -> biosynthesis

NO3- and SO₄^2- are used for electron flow

O2 is given off

S⁰ used in proton motive force to yeild ATP

Question 12

Chemolithotrophy - electron flow during Fe 2+ oxidation by the acidophile Acidithiobacillus ferrooxidans

Answer 12

Ferrous iron oxidation begins in the outer membrane where a cytochrome C proteins oxidizes Fe2+ to Fe3+

Electron transferred to periplasmic protein Rusticyanin which then reduces cytochrome c, and this subsequently reduces cytochrome a

Cytochrome a interacts with O2 to form H2O

ATP is synthesized by ATP synthase in the membrane

Autotrophy in Acidothiobacillus ferrooxidans is driven by the Calvin cycle

Question 13

Energetics and carbon flow on Phototrophic metabolism

Answer 13

• Photo heterotrophy

biosynthesis made from organic compounds

Photoautotrophy

biosynthesis made from CO2

Light->Electron flow->Proton motive force -> ATP

Question 14

Two types of Phototrophs

Answer 14

Anoygen (purple and green bacteria)

reducing power comes from H₂S -> S⁰ -> SO4^2-

Oxygenic (cyanobacteria, algae, green plants)

reducing power from H2O-> 1/2O2

both use light to make ATP from ADP

Question 15

Bacterial photosynthetic membranes

Answer 15

Chlorophylls and associated components of light gathering machinery are located in various membrane structures

Allows production of energised membrane

Varied arrangements

Cell membrane (CM) derived vesicles (purple bacteria)

CM itself (Heliobacteria)

Both CM and physically associated chlorosomes (Green bacteria)

Thylakoid type membranes similar to chloroplasts (cyanobacteria)

Question 16

whats the electron flow in anoxygenic photosynthesis in purple bacteria

Answer 16

steps in photosynthetic electron flow are much the same as that of respiratory electron flow

For a purple bacterium to grow autotrophically, the formation of ATP is not enough

Reducing power (NADH) is also necessary

Reduced substances such as H2S are oxidized and the electrons eventually end up in the “quinone pool” of the photosynthetic membrane

Question 17

Whats the arrangement of Protein complexes in the photosynthetic membrane of purple photosynthetic bacterium

Question 18

the calvin cycle

Answer 18

The Calvin cycle

Named for its discoverer Melvin Calvin

Fixes CO2 into cellular material for autotrophic growth

Requires

NADPH, ATP, ribulose bisphophate carboxylase (RubisCO), and phosphoribulokinase

6 CO2 to 1 molecule of glucose

Green sulfur bacteria use the reverse citric acid cycle to fix CO2

Green non-sulfur bacteria use the hydroxypropionate pathway to fix CO2