Respiration Flashcards
What is the equation for respiration?
Glucose + Oxygen –> Carbon dioxide + Water + ATP
C6H12O6 + 6O2 –> 6CO2 + H2O + ATP
Why is glucose not suitable as an immediate energy source
The release of energy would be too large, would produce too much heat and would be uncontrolable
How is the mitochondria adapted to its function
-Highly folded membrane forming cristae–> large surface area- greater number of chemical reactions
-70s ribosomes for protein synthesis- reactions can occur faster
-ATP synthase to produce large amounts of ATP.
-thin membrane- short diffusion distance
-circular DNA- own genome so transcription and translation can happen faster.
Where does each stage of respiration occur
- Glycolysis- cytoplasm/ cytosol of the cell
- Link reaction- matrix of the mitochondria/ mitochondrial matrix
- Krebs cycle- mitochondrial matrix
- ETC- mitochondrial membranes
State the two ways that ATP can be generated
- Substrate-level phosphorylation- ATP generated directly through energy released via respiration reactions. this occurs in Glycolysis and the krebs cycle
- Oxidative Phosphorylation- ATP generated from chemical energy released when a reduced hydrogen carrier or coenzyme has been oxidised in the ETC.
Explain the process of glycolysis.
Involves the conversion of glucose to pyruvate
1. Activation of glucose my phosphorylation, requires the hydrolysis of 2 X ATP to 2X ADP
2. Glucose phosphate then splits into 2 X Triose Phosphate
3. Triose Phosphate is oxidised to pyruvate involving the loss of H with the use of dehydrogenase enzyme which reduces NAD to NADH2. ATP produced via substrate level phosphorylation
What are the net yields for glycolysis
2 ATP
2 Reduced NAD
2 Pyruvate
Explain the process of the link reaction
Pyruvate is actively transported into the mitochondrial matrix (Low concentration in cytoplasm and high concentration in the matrix
1. Pyruvate (3C) is oxidised to acetate and the Hydrogen is removed to reduce NAD and a molecule of coenzyme A binds producing the final product of acetylcoenzyme A. Co2 is also lost in this reaction through decarboxylation. No ATP is produced
The link reaction net yield
2 NADH
2 CO2
2 AcetylCoenzyme A
Pyruvate (3c) + NAD + coA –> Acetylco A (2C) + NADH2 + CO2
Describe the process of the krebs cycle
A series of redox reactions that takes place in the matrix of the mitochondria.
1. 2C acetyl Co A combines with 4C molecule to produce a 6C molecule. NAD+ is converted to NADH2 through the addition of a H+ ion from pyruvate. CO2 is released through decarboxylation.
2. This forms a 5Carbon compund
3. Substrate level phosphorylation where ADP + Pi forms ATP. FAD forms FADH2, 2X NAD+ forms 2X NADH2 forming a 4 carbon compound. CO2 released again between 5c and 4c.
Net yields of the krebs cycle
1 Acetyl CoA produces 2CO2, 3NADH, 1FADH, 1 ATP but because the cycle happens twice the net yield is:
4 CO2
6 NADH
2 FADH
2 ATP
What is the overall net yield for the three processes
per glucose molecule:
10 NADH
4ATP
2FADH
Describe the ETC
The reduced Hydrogen carriers produced in glycolysis, link and krebs cycle will produceATP in the oxidative phosphorylation
1. Reduced NAD and FAD are oxidised losing H+
2. the electrons from the hydrogen atom pass down the ETC in the mitochondrial membranes in a series of redox reactions
3. As they pass down they lose energy which some is used to pump H+ through the inner mitochondrial membrane and into the intermembrane space
4. Some energy lost as heat
5. H+ diffuse down a proton gradient into the matrix via ATP synthase
6. Electrons and H+ combine with O2 gas to form water
7. O2 is the final terminal electron acceptor.
Water is a waste product of aerobic respiration. describe how water is formed
- Oxygen is terminal electron acceptor
- Combines with electrons and protons to form water
Describe the roles of the coenzymes and carrier proteins in the synthesis of ATP
- Reduced NAD and FAD
- electrons transferred from coenzyme to coenzyme through a series of redox reactions
- energy released as electrons pass down ETC
- Energy used to synthesise ATP from ADP + Pi
- Protons diffuse back through ATP synthase