Unit 5: Respiration Flashcards
How much ATP is produced from Aerobic respiration?
- Involves the complete breakdown of glucose
- releases more energy and produces much more ATP
What is the equation for Aerobic respiration?
C6H12O6 + 6O2 > 6CO2 + 6H2O + (~36ATP)
glucose + oxygen > carbon dioxide + water + energy
How much ATP is produced from Anerobic respiration?
glucose isn’t completely broken down
produces only 2 ATP
What is the equation for Anaerobic respiration in animals
C6H12O6 > 2C3H6O3 + (2ATP)
Glucose > Lactate + Energy
What is the equation for Anaerobic respiration in Yeast?
C6H12O6 > 2C2H5OH + (2ATP)
Glucose > Ethanol + 2CO2 + Energy
Where does Glycolysis occur
Cytoplasm
Where does the link reaction occur
Matrix
Where does the Krebs cycle occur?
Matrix
Where does Oxidative Phosphorylation occur
Cristae
What are cristae
folds of the inner membrane of the mitochondria
Which processes only occur in aerobic respiration?
- Link reaction
- Krebs cycle
- Oxidative Phosphorylation
What happens during glycolysis
Glucose(6C) is split into 2 pyruvate(3C) molecules
Glucose first converted into triose phosphate (3C)
Outline glycolysis
- Two ATP molecules are used to phosphorylate glucose to make it more reactive &Triose phosphate is formed
- TP is oxidised (H+ removed) into pyrvate, releasing energy
- Hydrogen atoms are accepted by coenzyme NAD forming 2 reduced NAD
- ATP is produced by substrate-level phosphorylation
- 4 ATP molecules are produced for every phosphate
- Net gain of 2 ATP molecules per glucose
- Pyrvate it then actively transported into the mitochondria
What is NAD
a coenzyme and it transports hydrogen to the electron transfer chain and more ATP can be produced by oxidative phosphorylation
What happens during glycolysis if oxygen isn’t present
anaerobic respiration will occur
- glycolysis still occurs but the pyrvate remains in the cytoplasm and and is converted into different products
Outline the Link reaction
- Pyruvate is oxidised and carbon dioxide is removed
- 2 hydrogen atoms are accepted by NAD to form Reduced NAD
- Acetate (2C) is produced and Coenzyme A is added to form Acetyl Coenzyme A
What happens during the Krebs cycle
a series of oxidation-reduction reactions
Outline the Krebs cycle
- AcetylCoA (2C) combines with a 4C molecule to form a 6C molecule which then enters the Krebs cycle
- CoA is removed and the 6C enters a cycle of reactions resulting in the reformation of the 4C
- The cycle involves the removal of CO2 and Hydrogen
- H atoms are removed and passed to NAD and FAD to formed 2 reduced NAD and reduced FAD
- These reduced coenzymes pass the hydrogen atoms to the ETC producing ATP via oxidative phosphorylation
- Each cycle produced 1 ATP via substrate level phosphorylation
How many times does the link reaction and Krebs cycle occur
The link reaction and Krebs cycle occur twice per glucose molecule as 2 pyruvate molecules ae produced in glycolysis
What are other respiratory substrates?
- fatty acids and glycerol
- amino acids where the amino group has been removed
- these also enter the Krebs cycle
What are the two main methods of producing ATP during aerobic respiration?
- substrate level phosphorylation
- oxidative phosphorylation
What is substrate level phosphorylation
occurs during Krebs cycle and Glycolysis
- Certain reactions release sufficient energy for the direct formation of ATP from ADP and Pi
- the ETC is NOT involved
Why is oxygen important
It is the final electron acceptor without it the ETC can’t function, aerobic respiration would stop and no ATP would be produced from so O.P
Outline oxidative phosphorylation
- Reduced NAD and FAD are oxidised releasing hydrogen to the first electron carrier of the ETC.
- Hydrogen splits into an electron and proton
- Electrons pass down carriers at decreasing energy levels. The energy released is used to actively pump the protons across the inner membrane to the intermembrane space. some energy is released as heat
- A proton gradient is established, theres a higher conc or protons in the intermembrane space than the matrix
- the gradient means the protons diffuse back across the inner membrane into the matrix via ATP synthase
- The movement of protons through ATP synthase releases energy whihc is used to from ATP from ADP and Pi
- At the end of the chain the electrons combine with protons and O2 to form water, O2 is the terminal electron acceptor
What is oxidation
the removal of a hydrogen atom from respiratory substances
What is phosphorylation
the formation of ATP by the addition of phosphate to ADP
What happens during Anaerobic respiration
involves glycolysis and production of pyruvate
- however the pyruvate doesnt enter the mitochondria but remains in the cytoplasm
What is produced during Aerobic respiration?
pyruvate is reduced using reduced NAD produced in glycolysis
enables the regeneration of NAD as the reduced NAD is converted to NAD
this ensures a continual supply of NAD so gycolysis can continue
What is the equation for Anaerobic respiration in animals (with pyruvate)
Pyruvate+ Red NAD > Lactate + Ox NAD
What is the equation for Anaerobic respiration in fungi/plants (with pyruvate)
Pyruvate + Red NAD > Ethanol + CO2 + Ox NAD
What happens if NAD is not regenerated
glycolysis would eventually stop as all the NAD would be reduced and there would be no NAD available to allow the oxidation of triose phosphate
What is a respirometer?
a device used to measure the rate of respiration of a living organism by measuring the uptake of oxygen or the release of CO2
What is the control variable when using a respirometer?
the mass of the organism
What is the purpose of the spring clip in a respirometer
allows the pressure throughout the apparatus to equilibrate with atmospheric pressure
Where is the coloured fluid in a respirometer?
In a narrow bone capillary tube to ensure max movement of fluid with any change of volume
What is the purpose of the rubber stopper in a respirometer?
airtightness
this can be improved by smearing vaseline along the seal between the chamber and stopper
What is the purpose of the respiratory chamber in a respirometer?
has a low volume to ensure that volume changes due to respiratory activity are significant enough to be measured
What is the purpose of the Filter paper wick in a respirometer?
ensures max surface area of potassium hydroxide solution is available to the contents of the chamber
What is the purpose of Potassium hydroxide solution in a respirometer?
to absorb CO2 evolved during respiration
What is the purpose of the Graduated scale in a respirometer?
measures movement of the coloured liquid
What is the purpose of the gauze basket in a respirometer?
holds respiring material
must be porous to permit free exchange of gases
What is the purpose of the Glass rod in a respirometer?
to keep the respiring material out of direct contact with the potassium hydroxide solution
How does the respirometer work to measure the uptake of O2?
- when organisms in the respirometer respire aerobically O2 is absorbed
- **CO2 given off in respiration is absorbed by potassium hydroxide
- therefore the volume inside the respirometer decreases meaning the pressure decreases so the bubble/coloured fluid moves to the left
What do you need to know in order to calculate the rate of O2 consumption?
Distance travelled by dye (d) in mm/cm
Radius of tube - allows you to convert distance moved into volume (πr²d)
Time - to calculate rate
O2 consumption - can then be expressed as rate (e.g volume per time, cm3 min-1
What other equipment is needed for the respirometer?
Ruler - to measure distance travelled by fluid
Stopwatch - to measure time
How does the respirometer work to measure the uptake of CO2?
Exact same way as O2 without the potassium hydroxide (its often replaced by water)
- the movement of the coloured fluid is recorded
- any difference between movement with KOH and without must be due to the production of CO2
How do you calculate the volume of CO2
volume of O2 consumed with KOH - movement of fluid without KOH
