Catabolism on chemoorganotrphs

Question 1

3 ways biology generates ATP

Answer 1

-substrate level phosphrylation
-oxidative phosphorlyation
-photophosphorylations

Question 2

substrate level phosphrylation

Answer 2

-ATP generated as a product of a metabolic reaction
-exergonic rxn - use excess energy to make ATP

Question 3

oxidative phosphorylation

Answer 3

-energy from electron transfer generate a proton motor force, which is used to generate ATP

Question 4

photophosphorylation

Answer 4

-energy captured from light is used to generate proton motive which is used to generate ATP

Question 5

catabolism of glucose

Answer 5

-for many chemoorganotrophs, sugars like glucose are a preferred energy source. They carry out the net reaction above in a series oxidation reactions
-many other organic compounds can also be used to generate enrgy, often using overlapping pathways
-many other sugars can be used too

Question 6

glycolysis

Answer 6

-glucose broken down to two pyruvate molecules over several steps
-found in all domains of life
-quick way to produce energy from glucose also feeds into CAC
-does not require O2
-can be followed by either respiration or fermentation

Question 7

glycolysis photo

Answer 7

Question 8

glycolysis overall net reaction

Answer 8

Question 9

citric acid cycle

Answer 9

-step 1- pyruvate converted to acetyl COA, Acetyl COA then enters the CAC
-sugars and other organic molecules can feed into the CAC
-cycle not just for catabolic purposes also provides key metabolic intermediates used anabolic reaction
-not just found in aerobic chemotrophs
-takes place in mitochondria in eukaryotes

Question 10

citric acid cycle photo

Answer 10

Question 11

citric acid cycle overall

Answer 11

Question 12

CAC and redox imbalance

Answer 12

-CAC did not solve our redox imbalance from glycolysis it made it worse
-the electron transport chanin and respiration is how this is solved

Question 13

electron transport chain

Answer 13

-cytoplasmic membrane (inner mitochondrial membrane for eukaryotes)
-redox baalnce restored and eNAD+ (electron carrier) regenerated
-electrons passed down a series of electron carriers with increasingly negative reduction potentials until a final electron acceptor is reduced
-P+ pumped out of cell to generate proton motive force
-O2 is terminal electron acceptor

Question 14

electron transfer in ETC

Answer 14

-from lower reduction potential carriers to higher reduction potential carriers and then to a final electron acceptor
-final electron acceptor gets used up, so you need a continous source to keep this going

Question 15

iron sulfur proteins

Answer 15

-key electron carrier
-metal cofactors used by many different proteins involved in electron transfer
-ETC comlexes often contains multiple Fe/S cluster
-oxidation state and reduction potential varies depending on nature and cluster of protein

Question 16

quinones

Answer 16

-key electron carrier
-not protein - small molecule that move within membrane
-accept 2 electrons transfer to next carrier in chain
-often serve to link Fe/S proteins to cytochromes

Question 17

cytochromes

Answer 17

-cytochromes are proteins that contain heme prosthetic groups
-different proteins/different heme groups, different reduction potentials
-ETC compelxes often contain multiple cytochromes-typically the last stop before terminal acceptor

Question 18

electron transport chain paracoccus dentrificans

Answer 18

Question 19

complexes

Answer 19

multiple proteins
-can include proton pumps that couple energetically favourable electron transfer to proton pumping

Question 20

where can electrons enter in the ETC in paracoccus dentrificans example

Answer 20

-this specific can enter at complex I or Complex II
-complex one starts with NADH and pumps 4 p+ per 2e- to generate more energy
-complex II starts with FADH2, pumps fewer protons
-from either complex I or II, quinone is reduces and passes electrons on to complex III

Question 21

hoe many protons pumped from NADH to H2O in ETC paracoccus example

Answer 21

-10 protons per NADH

Question 22

ATP synthase

Answer 22

-proton motive force to ATP
-protons flow back along their gradient-generates mechanical energy
-mechanical energy then used to power the phosphorylation of ADP–> ATP
-approx 3.3 H pumped needed to generate 1 ATP
-reversible, ATP hydrolysis ca generate PMF

Question 23

how many ATP per NADH

Answer 23

3

Question 24

metabolic flexibility of chemoorganotrophs

Answer 24

-chemoorgannotroph have preferred energy source but can use a variety of other molecules such as fatty acids –> acetyl CoA and AA converted to entry pounts to CAC
-many possible terminal electron acceptors
-some microbes have the ability to use multiple different terminal electron acceptors

Question 25

Ecoli aerobic and anaerobic respiration

Answer 25

-facultative anaerobe
-can do respiration, anaerobic respiration and fermentation
-can assemble different electron transport chains
-under aerobic conditions conditions can respire using nitrite or DMSO
-nitrate respiration is less efficient as it puumps fewer protons than with O2

Question 26

fermentation

Answer 26

-chemotrophic metabolism without use of an external electron acceptor
-anaerobic
-substrate level phosphorylation can be used to generate ATP
-Redox balance achieved by excretion of reduced fermentation products

Question 27

Lactic Acid fermentation

Answer 27

Question 28

ethanol fermentation

Answer 28

Question 29

Diversity of fermentation

Answer 29

-microbes can fermenet a wide range of organic compounds (AA, Fatty acids, purines and pyrimdines)
-a range of other fermentation products can be made
-generate energy rich molecule that can be hydrolyzed to produce ATP, donate electrons to reduce a metabolite and excrete it to obtain redox balance
-fermentation can vary from last report option to the sole source of energy

Question 30

beer

Answer 30

-ethanol generated by yeast alcoholic fermnatation used to make alcoholic beverages
-The CO2 generated by alcoholic fermentation used to make dough rise
-the CO2 can also be used to naturally carbonate beer