Topic 4 - Microbial metabolism

Question 1

What is ATP and what is it used for?

Answer 1

ATP is adenosine triphosphate. It is hydrolysed to drive reactions, i.e. is it the universal energy storage molecule. When a bond it broken ATP is released.
Simple molecules use this to make complex molecules and both simple and complex molecules are oxidised to generate ATP from ADP + Pi.

Question 2

Summarise how ATP is made.

Answer 2

Glucose is oxidised —– gives up electrons and protons (NAD is an electron carrier from one biochemical pathway to the next without it pathway is blocked) —- cells harness CO2 and H2O to make ATP.

C6H12O6 + 6O2 —— 6CO2 + 6H2O + 38ATP
glucose is converted
to pyruvate

Question 3

What is a redox reaction?

Answer 3

Reaction where the final electron acceptor is oxygen.

Question 4

What is ETC?

Answer 4

The electron transport chain.

Question 5

What happens in the ETC?

Answer 5

NADH passes both electrons and protons down the ETC. Protons are pushed outside the cell membrane and electrons pass from one cytochrome to the next 'flow downstream', towards ATPase. 
ATP synthase (enzyme) then harnesses proton gradient and reduces O2 to H2O which makes ATP.

Question 6

Where does the ETC occur in bacteria and how is this different to eukaryotes?

Answer 6

In bacteria the ETC occurs in the cell membrane and space and in eukaryotes in taken place in the mitochondria.

Question 7

What is the respiration process?

Answer 7

Glycolysis —– preparatory step —— krebs cycle —- 38 ATP.

Question 8

What is the difference between catabolic and anabolic?

Answer 8

Catabolic - provides energy (glucose mainly).
Anabolic - uses energy to build large blocks

C before A.

Question 9

What happens in the glycolysis stage of respiration?

Answer 9

This is where glucose is oxidated to pyruvic acid and 2 NADH’s are produced.
2 ATP’s are formed through substrate-level phosphorylation and 6 ATP’s through oxidative phosphorylation and ETC.

Question 10

What happens in the preparatory stage of a redox reaction?

Answer 10

Acetyl CoA is formed which produces 2 NADH’s

6 ATP’s through oxidative phosphorylation and ETC.

Question 11

What happens in the Krebs cycle of a redox reaction?

Answer 11

Acetyl CoA is oxidised to make succinic acid and this produces 6 NADH’s and 2 FADH’s.
2 GTP’s (equivalent to ATP)
18 ATP through oxidative phosphorylation and ETC and another 4 ATP’s through OP and ETC.

Question 12

What is anaerobic respiration and how does it differ to aerobic respiration.

Answer 12

Anaerobic respiration is when the final electron acceptor is not oxygen rather an organic molecule such as NO3-, SO4- and CO3-2.
Aerobic has oxygen as the final electron acceptor.

Question 13

Which produces more energy fermentation or respiration? Why?

Answer 13

Respiration. In fermentation there is no ETC and krebs cycle therefore less ATP production.

Question 14

What is fermentation used for?

Answer 14

Fermentation is used for:

• Alcohol and acidic dairy production
• Food spoilage
• Large scale microbial process with no air.

Question 15

What is the process of fermentation?

Answer 15

Glycolysis (glucose) —- 2 pyruvic acids —- formation of fermentation end product.

Question 16

What happens in the glycolysis stage of fermentation.

Answer 16

2 NADH’s and NAD+’s and there is 2 ADP’s and 2 ATP’s.

Question 17

What happens in the 2 pyruvic acid stage of fermentation?

Answer 17

2 NADH’s and 2 NAD+’s

Question 18

What are the bi-products of alcohol fermentation?

Answer 18

Ethanol and CO2.

Question 19

What are the bi-products of lactic acid fermentation?

Answer 19

Lactic acid.

Question 20

What is heterolactic?

Answer 20

When lactic acid fermentation produces lactic acid and another bi-product such as acetone etc.
This is used for yogurt and cheese as it has more flavour.

Question 21

What is homolactic?

Answer 21

When only lactic acid is the bi-product produced.

Question 22

How is lacto bacillus fermented?

Answer 22

It is fermented by increasing the salt levels and made anaerobic.

Question 23

Define: 
Photoautotrophs
Photoheterotrophs 
Chemoautotrophs 
Chemoheterotrophs

Answer 23

Photoautotrophs - use light (energy source) and CO2 (carbon source).
Photoheterotrophs - use light as energy source and organic compounds as carbon source.
Chemoautotrophs - use chemicals as energy source and CO2 as carbon source.
Chemoheterotrophs - use chemicals as energy source and and organic compounds as carbon source.

Question 24

What are photoautotroph examples?

Answer 24

oxygenic - cynobacteria and plants

anoxygenic - green and purple bacteria.

Question 25

What are chemoautotroph examples?

Answer 25

Iron-oxidising bacteria.

Question 26

What are photoheterotrophs examples?

Answer 26

Green bacteria and purple nonsulfur bacteria.

Question 27

What are Chemoheterotroph examples?

Answer 27

Fermentative bacteria, animals, plants, protozoa, fungi and bacteria.