Cellular Respiration Flashcards
What is cellular respiration?
The break down of Glucose into ATP
What is ATP?
Adenosine Triphosphate which is a nucleotide
What makes up ATP?
A ribose sugar, adenine nitrogenous base and a triphosphate group
What does ATP do?
Provides energy to drive cellular processes and mediate the transfer of energy from reactions that release energy to those that require energy
What are reactions that require energy called?
Endergonic
What are reactions that release energy called?
Exergonic
How does ATP store energy?
High energy phosphoanhydride bond
How does ATP release energy?
When the phosphoanhydride bond is hydrolysed
ATP + H20 ——-> ADP + pi + energy
How is ATP regenerated?
Energy from exergonic reactions can be used to add a phosphate group to ADP
What does substrate level phosphorylation do?
The transfer of a phosphate from a substrate with the energy coming from the substrate which is converted from a high to low energy in the process
Where does substrate level phosphorylation occur?
Glycolysis and Krebs cycle
What work can ATP do?
Transport, Mechanical and Chemical work
What is NAD?
Nicotinamide Adenine Dinucleotide is a coenzyme important for cellular respiration
How can NAD exist?
As NAD+ (oxidised) and NADH (reduced)
What does NAD do?
It acts as a carrier of energy and transports electrons from 1 reaction to another by trapping them
How does NAD work?
When a molecule is oxidised, 2H atoms are removed as a hydride ion (H-) and a hydrogen ion (H+). H- is transferred to NAD+ and H+ is released into the solution
Where does glycolysis occur?
In the cytosol
What is the process of glycolysis?
6 Carbon glucose is broken down into 2 pyruvates with 3 carbons
What does the energy releasing phase of glycolysis create?
ATP and NADH
What are the 2 phases of glycolysis?
Energy-requiring and energy-releasing
What are the first 2 steps of the energy-requiring phase of glycolysis?
- Phosphate group transferred from ATP to glucose
- Glucose-6-phosphate is converted into
fructose-6-phosphate (isomer)
What are the 3rd and 4th stage of glycolysis?
- Phosphate group transferred from ATP to fructose-6- phosphate
- Fructose-1,6-bisphosphate splits to form two three- carbon sugars: DHAP and glyceraldehyde-3-phosphate
What is the relationship between DHAP and glyceraldehyde-3-phosphate?
They are isomers and DHAP converts easily to glyceraldehyde-3-phosphate
What is the deficiency of glycolysis energy-requiring stage?
2 ATP
What happens to glyceraldehyde-3-phosphate in the energy-releasing stage of glycolysis?
It is oxidised while NAD+ is oxidised to NADH
What is the extra energy generated used for in glycolysis?
Phosphorylating glyceraldehyde-3-phosphate
How much energy is generated in the energy-releasing stage of glycolysis?
4 ATP and 2 NADH
What is the net gain of glycolysis?
2 NADH and 2 ATP
What is Pyruvate Oxidation?
AcetlyCoA is produced
How does Pyruvate Oxidation occur?
Pyruvate is decarboxylated to release CO2. The 2C group left oxidises to form an acetyl group which attached to Coenzyme A to form Acetyl CoA. NAD+ is reduced to NADH
What happens when oxygen isn’t available for Pyruvate Oxidation?
Pyruvate is reduced to lactate with electrons coming from NADH
Where does the Krebs cycle occur?
In the mitochondrial matrix
What occurs in the Krebs Cycle?
Decarboxylation reactions that release CO2
Oxidation-Reduction reactions where Acetyl CoA derivatives are oxidised and NAD+ and FAD are reduced to NADH and FADH2
How many Acetyl CoA does each glucose generate?
2
Where does Oxidative Phosphorylation occur?
Inner mitochondrial membrane
What does Oxidative Phosphorylation use?
The electron transport chain
What is the electron transport chain?
A series of membrane protein complexes and other molecules that act as electron carriers
How does the electron transport chain work?
Carriers are reduced (gain electrons) and oxidised (lose electrons) which releases energy
What makes up the electron transport chain?
4 complexes and 2 mobile electron carriers
Where do electrons in the electron transport chain come from?
NADH and FADH2 produced in glycolysis and Krebs cycle
How is a concentration gradient produced in ETC?
Electrons pass through the chain and energy is used by the electron carrier complexes to pump H+ ions across the mitochondrial membrane
How do electrons from NADH reach the electrons carriers?
NADH cannot easily cross the mitochondrial membrane so a shuttle system is used to deliver electrons
What is chemiosmosis?
The use of energy in a H+ gradient to drive cellular work
What does the pH gradient in chemiosmosis provide?
A proton motive force that is used to convert ADP to ATP
What is the enzyme that catalyses chemiosmosis called?
ATP Synthase
How much ATP do NADH and FADH2 produce?
NADH yields 2.5 ATP and FADH2 yields 1.5 ATP
What is the total ATP gain of glycolysis and the Krebs Cycle?
28ATP from 10 NADH and 2 FADH2
What is the Walburg effect?
Tumours convert glucose to lactate even in the presence of adequate oxygen
Why is glucose converted to lactate in tumour cells?
Glucose to lactate is 10-100x faster than the oxidation of glucose and can generate 2 ATP per glucose molecule
How does lactate favour the tumour?
The immune response is dampened and the environment is acidified
Why are more glucose-derived metabolites favoured by the tumour?
DNA replication and RNA transcription, Membrane production and Protein translation are all increased so the cell is proliferated
