3.5.2 - Respiration Flashcards
What are the 4 stages of aerobic respiration and where do they occur ?
- Glycolysis - cytoplasm
- Link reaction - mitochondrial matrix
- Krebs cycle - mitochondrial matrix
- Oxidative phosphorylation - mitochondiral inner membrane cristae
What is glycolysis ?
The first stage of anaerobic and aerobic respiration
- It doesnt require energy, O2 or ATP to actively transport it into the mitcohondria
Steps of glycolysis (1)
1) Phosphorylation of glucose, ATP will hrydrolyse a phosphate group and add it to glucose. 2 ATP is used to do this. - Add 2 phosphate groups to glucose - glucose phospate
Glycolysis (2)
Glucose phosphate is very high energy so it splits into two molecules of triosphosphate
Glycolysis (3)
Triosphosphate is oxidised into pyruvate with a net gain of 2 ATP and 2 NADH
What does gaining a hydrogen show ?
It shows that it is reduced as a H+ atom is a proton and an electron
What are the products of glycolysis ?
2 x pyruvate
net gain of 2 ATP
2 x NADH
In areobic respiration, where does the pyruvate made in glycolysis go ?
It is actively transported into the mitochondrial matrix for the next step.
The stages of the LINK REACTION
- The pyruvate made is decarboxylated and oxidised to form acetate.
- NAD is reduced, forming NADH.
- Acetate combines with CoA to make acetyl CoA.
What are the products made in this stage ?
- 2 x Accetylcoenzyme A
-2 x CO2 - 2 x Reduced NAD
2 of each as the reaction occurs twice to create two pyruvates
The stages of the KREBS CYCLE
(1)
- Acetyl coA combines w/ 4c molecule (oxaloacetate), forming 6c citrate.
- CoA goes back to link reaction to be used again.
The stages of the KREBS CYCLE
(2)
- The 6c citrate is converted into a 5c molecule
- Decarboxylation occurs, as well as dehydrogenation so both CO2 and H are removed.
- The H is used to produce NADH
The stages of the KREBS CYCLE
(3)
The 5c molecule is converted into a 4c molecule.
- Decarb & Dehyd occur, producing one molecule of FADH and 2x NADH
- ATP = produced by direct transfer of phosphate group from intermediate compound to ADP.
What is substrate - level phosphorylation ?
When a phosphate group is directly transferred from one mol to another.
The products of the KREBS cycle are …?
Per cycle :
- 3 x NADH
- 1 x FAD
- 1 x ATP
- 2 x CO2
per glucose - multiply all by 2
What is oxidative phosphorylation ?
The process where energy carried by electrons from reduced coenzymes (NADH and FADH) is used to make ATP.
How does OX. PHOS. work ?
Steps 1 - 2
1) H atoms are released as NADH and FADH are oxidised to NAD and FAD. The H+ ions split into protons and e-
2) Electrons move down the ETC ,losing energy at each step.
How does OX. PHOS. work ?
Steps 3-4
3) the energy is used by electron carriers to pump protons from the matrix into intermembrane space
4) The con of protons is higher in the space than the matrix, forming an electrochemical gradient
How does OX. PHOS. work ?
Steps 5-6
5) Protons move down the gradient, across the inner membrane and into the matrix via ATP synthase. - ATP is synthesised here from ADP and Pi
6) The forming of the ATP is driven by H+ ions moving across a membrane - chemiosmosis.
How does OX. PHOS. work ?
Step 7
In the mito matrix, at the end of the ETC, protons, e- and O2 combine to form water.
Oxygen is the final e- acceptor
What can ATP production be affected by ?
Mitochondrial diseases which affect the functioning of mitochondria.
they effect how proteins in ox. phos. or Kreb’s cycle function which reduces ATP production.
What causes an increase lactate concentration in the blood ?
Mitochondrial diseases can cause anaerobic respiration to increase and lots of lactate therefore builds up, causing muscle fatigue and weakness.
Some diffuses into bloodstream leading to a high con of lactate.
What can other respiratory substances be used for ?
Other respiratory substances can be used in aerobic respiration.
Some products resulting from the breakdown of other molecules : fatty acids, AAs - can be converted into molecules able to enter Kreb’s.
Anaerobic Respiration is when ?
Respiration in the absence of O2 and it occurs only in the cytoplasm
What produced in glycolysis is reduced?
How is it reduced?
The pyruvate produced is reduced to form ethanol and CO2(in plants and microbes) or lactate in animals
- This is reduced by gaining a H from reduced NAD
What does the pyruvate produced in glycolysis do to NAD?
Oxidises it so it can be reused in glycolysis and ensure ATP continues to be reduced
