9 Cellular Respiration and Fermentation Flashcards
Note:
Generally speaking, this set of cue cards will use simply ‘respiration’ to refer to ‘anaerobic respiration’
What does cellular respiration include?
Technically both aerobic and anaerobic (and excludign glycolysis) but it often just refers to aerobic.
What is reduction?
A gain of electrons (/hydrogen)
What is oxidation?
A loss of electrons (/hydrogen)
In redox reactions what do electrons typically travel with?
Protons i.e to form a hydrogen atom
How is energy from ATP carried?
By electron carriers
What electron carrier is typically used in respiration and why?
NAD+ because it can easily cycle between its oxidised (NADH) and reduced (NAD+ states)
What class of chemical is NAD+?
A coenzyme.
What does NAD stand for in NAD+?
nicotinamide adenin dinucleotide
How do electron carries collect electrons?
Enzymes called dehydrogenases remove two hydrogen atoms (2 electrons and 2 protons) from glucose etc. and thereby oxidise it.
One proton is released as H+. This leaves the electron carrier with an extra hydrogen (NAD–>NADH) and an electron which cancel the charge.
Why are electron carriers important?
They allow a controlled release in energy from glucose, not a brief explosion where little energy could be collected.
What is the highest energy form of NAD?
NADH
What are the stages of respiration?
Glycolysis, pyruvate oxidation & citric acid cycle and oxidative phosphorylation.
Where does glycolysis occur?
In the cytosol.
By what basic ways is ATP synthesised?
Oxidative phosphroylation and substrate-level phosphorylation.
What is oxidative phosphorylation?
The regeneration of ATP using the energy of an electron transport chain.
Note that it uses inorganic phosphates from the use of ATP.
What is substrate level phosphorylation?
The regeneration of ATP through the transfer of a phosphate molecule from a substrate to an ADP molecule.
What phases can glycolysis be divided into?
Energy investement phase and energy payoff phase
What is the net gain of ATP thorugh the glycolysis of one glucose molecule?
2 ATP
Per glucose molecule, how much ATP is used during the energy investement phase of glycolysis?
2 ATP molecules
Per glucose molecule, how much ATP is yielded during the energy payoff phase of glycolysis?
4 ATP molecules (net of 2)
In order, what are the substrates of the energy investement phase of glycolysis?
Glucose, Glucose 6-phosphate, Fructose 6-phosphate, Fructose 1,6-bisphosphate and Dihydroxyacetone/Glyceraldehyde 3-phosphate.
In order, what are the enzymes of the energy investement phase of glycolysis?
Hexokinase, Phosphoglucoisomerase, Phosphofructokinase, Aldolase and Isomerase
How many stages are there of the energy investement phase of glycolysis?
5.
What is Step 1 of Glycolysis?
ATP is added to Glucose by Hexokinase, turning it into Glucose 6-phosphate.
What is Step 2 of Glycolysis?
Phosphoglucoisomerase converts Glucose 6-phosphate to its isomer Fructose 6-phosphate.
What is Step 3 of Glycolysis?
Fructose 6-phosphate is converted to Fructose 1,6-biphosphate using phosphofructokinase and ATP.
What is Step 4 of Glycolysis?
Aldolase cleaves Fructose 1,6-biphosphate into two 3 carbon sugars: dihydroxyacetone and glyceraldehyde 3-phosphate.
What is Step 5 of Glycolysis?
Isomerase catalyses the conversion of Dihydroxyacetone phosphate to its isomer glyceraldehyde 3-phosphate. Which is later used to the energy payoff phase.
When does the actual sugar splitting of Glycolysis occur and what does this mean?
In the 4th step of glycolysis in which Adolase cleaves Fructose 1,6-biphosphate into dihydroxyacetone and glyceraldehyde 3-phosphate.
The significance of this is that the energy payoff stage occurs twice per glucose molecule and thus yields ATP in units of 2.
In order, what are the substrates of the energy payoff phase of glycolysis?
Glyceraldehyde 3-phosphate → 1,3-Biphosphoglycerate → 3-Phosphoglycerate → 2-Phosphoglycerate → Phosphoenol pyruvate (PEP) → Pyruvate
In order, what are the enzymes of the energy payoff phase of glycolysis?
Triose phosphate dehydrogenase, Phosphoglycerokinase, Phosphoglyceromutase, Enolase, Pyruvate kinase
How many steps are there of glycolysis?
10
At what step does the energy payoff phase of glycolysis begin?
Step 6
What is Step 6 of Glycolysis?
Triosephosphatedehydrogenase oxides the Glyeraldehyde 3-phosphate by transfering electrons from it to NAD+, forming 2 molecules of NADH (per. gluc.)
The energy release from this reaction is used to add a phosphate to the substrate, formign 1,3 biphosphoglycerate
What is Step 7 of Glycolysis?
Phosphoglycerokinase removes a phosphate group from 1,3-biphosphoglycerate, yielding 3-phosphoglycerate and 2 ATP (per. gluc.)
What is step 8 of glycolysis?
Phosphoglyceromutase converts 3-phosphoglycerate to its isomer 2-phosphoglycerate.
What is Step 9 of Glycolysis?
Enolase converts 2-phosphoglycerate to Phosphoenol pyruvate (PEP) and H2O
During what phase of respiration is water formed?
Glycolysis (step 9: 2-phosphoglycerate to phospoenol-pyruvate(PEP) and water) and Oxidative phosphorylation
What is Step 10 of Glycolysis?
Phophoenol-pyruvate (PEP) is converted by pyruvate kinase to pyruvate and 2 ATP (per gluc.)
What is the end product of glycolysis?
Pyruvate.
In what steps of glycolysis is ATP used?
Step 1 (Glucose → Glucose 6-phosphate) and Step 3 (Fructose 6-phosphate → Fructose 1,6-biphosphate)
In what stages of glycolysis is ATP released?
7 (1,3-Biphosphoglycerate → 3-Phosphoglycerate) and 10 (Phosphoenol-pyruvate → Pyruvate)
What stages of Glycolysis involve the addition or release of chemicals other than ATP and substrates?
Step 6 (Glyceraldehyde 3-phosphate → 1,3-Biphoglycerate uses 2NAD+ to form 2NADH + 2H+; and it uses 2 phosphate groups) and Step 9 (2-Phosphoglycerate → Phosphoenol pyruvate (PEP) and H2O)
What occurs after glycolysis?
THe oxidation of Pyruvate to Acetyl CoA
What is the net input of glycolysis?
Glucose → 2 Pyruvate + 2H2O
2 ADP → 2 ATP
2 NAD+ + 2 H+ → 2 NADH
(per gluc.)
What does S-CoA represent?
Acetyl CoA (it is often found bound to a sulphur atom)
How many stages are there of Pyruvate oxidation?
3