Cellular Respiration Flashcards
Glycolysis
The breakdown of glucose to make pyruvate (3C) which is then used in the link reaction for Krebs cycle. Synthesises ATP
Steps in glycolysis
- Phosphorylation
- Lysis
- Oxidation
- ATP formation
Why are 2 ATP needed in phosphorylation?
It is needed to breakdown hexose sugar to hexose bisphosphate
Lysis (breaking down) steps
Breaks down 6C (1,6 bisphosphate) compound to 3C compound (triose phosphate). The 3C then stabilises into glycerate-3-phosphate
What is being oxidised in glycolysis?
The 3C compound sugar is being oxidised by removing the hydrogen atoms and donating it to NAD+ to make it into NADH
How is ATP synthesised in glycolysis?
The sugar intermediates from the 3C compound releases energy to make ADP become ATP
Where does the pyruvate moves to after glycolysis?
The pyruvate goes from the cytosol to the mitochondrial matrix through using carrier proteins
Link reaction
Decarboxylates pyruvate
2 hydrogen is lost and is used to make NAD+ to NADH
The compound becomes an acetyl group which is then combined with coA to make acetyl coA
TCA Cycle (Krebs cycle) purpose
Primarily used to make energy molecules such as NADH and ATP
What is the first step in Krebs cycle?
Oxaloacetate combines with acetyl coA to make a 6C compound (citrate)
How many times is the compound oxidised in Krebs cycle?
4 times, the last 2 times is when the 4C compound gives out hydrogen to reduce FAD and NAD
What is the net product of Krebs cycle
In one cycle
2x CO2
1x ATP
1x FADH2
3x NADH
Chemiosmosis
The action of maintaining the hydrogen ion gradient between the intermembrane space and mitochondrial matrix through using a transporter
ETC (Electron transport chain)
High ATP production takes place through using the energy molecules made and chemiosmosis
Steps in ETC:
- FADH2 and NADH oxidises and releases hydrogen
- Hydrogen breaks down to H+ + e-
- H+ is carried to intermembrane space using a hydrogen pump that is powered by e-
- e- is on an electron carrier that is used to give energy to other pumps as well
- Hydrogen ion builds up in space and diffuses down towards ATP synthase where ADP + Pi => ATP
What is the final acceptor of hydrogen in ETC?
oxygen. the end product is water
What is the process of using the harnessed energy (through ETC) to synthesise ATP called?
Oxidative phosphorylation. Oxygen is reduced to create ATP
Mitochondrial vs Photosynthetic ETC
Photosynthetic (Photophosphorylation) - Energy comes from light, powering delocalised electrons in photosystem 2 and 1
Mitochondrial - does not depend on light, depends on the presence of FADH2 and NADH from glucose
What is the end product of light dependent reaction?
ATP, NADPH and O2
Cyclic photophosphorylation
Does not involve reduction of NADP+ as there is not enough energy to do it
De-energized electron goes back to photosystem 1 (does not involve PS2)
Use it to conserve energy while still contributing to ATP synthesis
Non-cyclic photophosphorylation
Involves both PS2 and PS1. Photolysis of water is done to supply delocalised electron and hydrogen. Supplies PS1 with excited electron to be able to make NADPH and ATP
Alternative oxidase (AOX)
The protein that allows electron bypass ETC and combine with oxygen to water without giving energy to hydrogen pump
Uncoupling protein (UCP)
Provides a pathway for hydrogen ions to diffuse down to the matrix without powering the ATP synthase. The energy is dissipated as heat
Why do we need UCP and AOX?
To regulate ATP production
How does UCP contribute to plant thermogenesis?
UCP gives out heat when hydrogen moves down the gradient which then the plant uses that heat their tissues
How does thermogenesis (observing temperature) help measure the respiration rate of the plant
As oxygen is the final acceptor, the more oxygen is used due to AOX happening, it means that the plants respire more
