Unit 7 - Respiration Flashcards
Where does glycolysis take place?
In the cytoplasm.
Is glycolysis aerobic or anaerobic?
Anaerobic.
What are the steps of glycolysis?
1) Glucose is phosphorylated to glucose phosphate - using phosphates from 2 ATP molecules
2) This makes glucose more reactive
3) The glucose phosphate splits into 2 molecules of triose phosphate
4) Each triose phosphate is oxidised to pyruvate
5) An hydrogen reduces the coenzyme NAD to NADH (reduced NAD)
6) 2 ATP molecules are produced for each those phosphate to produce 4 ATP (via substrate level phosphorylation)
7) 2 ATP used, 2 ATP produced = net gain of 2.
Where does the link reaction take place?
In the matrix.
Steps of the link reaction?
1) Pyruvate enters the mitochondrial matrix by active transport
2) Pyruvate is oxidised to acetate releasing an H which reduces NAD to produce NADH
3) 2CO2 is also produced
4) Acetate combines with coenzyme A to produce acetylcoenzyme A
Products of glycolysis?
-2xNADH
-2xATP
-2xPyruvate
Products of the link reaction?
-2xacetylcoenzyme A
-2xNADH
-2xCO2
Where does the kerbs cycle take place?
In the matrix
Steps of the Krebs cycle?
1) Acetyl coenzyme A reacts with a 4 carbon molecule, releasing CoA, to make a 6 carbon molecule
2) The 6C molecule is oxidised into a 5C molecule and then oxidised back to the 4C molecule.
3) Coenzymes NAD and FAD are reduced to NADH and FADH
4) CO2 is lost
5) 2 molecules of ATP are produced by substrate level phosphorylation from ADP + Pi
Products of the Krebs cycle?
-6xNADH
-2xFADH
-2xATP
-4CO2
-2xCoenzyme A
Where does oxidative phosphorylation take place?
On the inner membrane of the mitochondria.
Steps of oxidative phosphorylation?
1) The reduced NAD and FAD are oxidised, donating a hydrogen and the hydrogen dissociates into a proton and an electron
2) The electrons pass down a series of electron carriers on the electron transfer chain via redox reactions
3) They lose energy, which is used to pump the H+ through the inner membrane into the intermembrane space, forming a H+ gradient
4) Some energy is also lost as heat
5) The H+ diffuse back through the inner membrane via ATP synthase. This is called chemiosmosis
6) This releases energy to form ATP from ADP + Pi
7) 2 ATP are formed
8) The electrons and the H+ combine with oxygen to form water
9) Oxygen is the terminal electron acceptor
How much ATP is produced from respiration?
38 ATP for 1 molecule of glucose
Definition of chemiosmosis?
The movement of ions across a selectively permeable membrane, down their concentration gradient.
In the absence of oxygen which processes stop?
The link reaction, Krebs cycle and oxidative phosphorylation stop as there is no oxygen to act as the terminal electron acceptor
How is NAD regenerated from NADH in anaerobic conditions to all glycolysis to continue?
To regenerate the NAD, the H from the reduced NAD reduces pyruvate to form:
-lactic acid in animals
-ethanol + carbon dioxide in plants
When you get a stitch from exercising why are you told to take a deep breath?
Oxygen is used to oxidise the lactic acid back to probate which can enter the link reaction to form more ATP.
How can lipids be used as respiratory substances?
-Lipids are hydrolysed to fatty acids and glycerol
-The glycerol is phosphorylated and converted to triose phosphate which enters glycolysis
-The fatty acids are broken down into 2C fragments which are converted to acetyl CoA which enters the Krebs cycle.
How are proteins used as respiratory substances?
-The protein is hydrolysed to amino acids.
The amino group is removed from the amino acids (deamination) and products enter respiration at different points:
+3C compounds are converted into Pyruvate
+4 and 5C compounds are converted to Krebs cycle intermediates
What 2 things can you measure to measure the rate of aerobic respiration?
-Rate of uptake of O2
-Rate of CO2 produced
When measuring anaerobic respiration is it common to use a layer of oil?
The layer of oil prevents oxygen reaching the yeast maintaining anaerobic conditions.
How can you use a manometer to measure aerobic respiration?
1) As the seeds aerobically respire they take in O2 and produce CO2
2) The CO2 is absorbed by the potassium hydroxide
3) This reduces the pressure and volume in the flask causing the coloured liquid to move towards the seeds
4) The distance the liquid moves in a set time determines the rate
5) By measuring the radius of the tube, the volume of gas used can be calculated
6) By measuring the mass of the seeds this can work out the rate per gram
Why might filter paper be used when measuring aerobic respiration?
To increase the surface area for the absorption of CO2
Before measuring the rate of respiration, the seeds are left at the desired temp with the syringe off for a day period of time. Give 3 reasons why?
1) To allow equilibrium to be reached/equilibrate to the correct temp
2) Allow for pressure change in the apparatus
3) Allow respiration rate of seeds to stabilise
