Respiration Flashcards
What is the equation for aerobic respiration
C6H12O6 + 6O2 -> 6H2O + 6CO2
What type of reaction is aerobic respiration
Oxidation
Aerobic respiration involves the oxidation of organic molecules to release what
Energy
What is the energy released from aerobic respiration used for
The synthesis of ATP from ADP and Pi
What are the 4 stages of respiration, list in order
- Glycolysis
- Link reaction
- Krebs cycle
- Electron transport chain
Where does glycolysis occur
In the cytoplasm
Where does the link reaction occur
In the mitochondrial matrix
Where does the Krebs cycle occur
In the mitochondrial matrix
Where does the electron transport chain occur
In the cristae / inner mitochondrial membrane
What type of proteins do the 70S ribosome code for in the mitochondria
Enzymes
Why is it important for membranes to be present within a cell, so around the organelles
To allow for compartmentalise so the concentration of enzymes for example necessary for respiration is high in the mitochondria where the respiration takes place
Why does glycolysis occur in the cytoplasm
It’s the location of the enzymes involved
What is the name of the enzymes used in glycolysis
Dehydrogenases
What happens to glucose in glycolysis
It’s phosphorylated by ATP to increase the reactivity
While glucose is phosphorylated, what also happens
ATP is hydrolysed into ADP and the Pi does the phosphorylating
When glucose is phosphorylated what is the product
Hexose diphosphate
What happens to the molecule when hexose diphosphate is converted into triose phosphate
The hexose diphosphate splits
From one hexose diphosphate molecule how many triose phosphate molecules are produced
2
What is the type of reaction that converts triose phosphate into pyruvate
Oxidation
What is the other way of saying triose phosphate is oxidised into pyruvate
Triose phosphate is dehydrogenased into pyruvate
When triose phosphate is oxidised into pyruvate, what is reduced
NAD to NADH2
What is produced when triose phosphate is oxidised into pyruvate
ATP is synthesised from 4ADP
How many ATP molecules are produced when triose phosphate is oxidised into pyruvate
4
When ATP is synthesised during the oxidation of triose phosphate during glycolysis, where does the energy come from
The reduction of NAD
When ATP is synthesised from ADP and Pi using the energy released during the reduction of NAD during glycolysis, what is the name process
Substrate level phosphorylation
What are the end products of glycolysis
- 2 pyruvate
- 2 ATP
- 2 NADH2
Why is the net gain of ATP 2 in glycolysis
SInce 2 ATP is used to produce the 4 ATP molecules so net gain of 2
What is the name of the process after glycolysis
Link reaction
Why does the link reaction occur in the mitochondrial matrix
It’s the location the enzymes
What is the name of the enzymes involved in the link reaction
Dehydrogenase
What type of molecule is pyruvate
Polar molecule
How does pyruvate enter the mitochondrial matrix
Through specific carrier proteins
Why can glucose not enter the mitochondria
As there are no glucose carriers in the mitochondrial membrane
What type of reaction is the conversion of pyruvate into acetate
Oxidation
When pyruvate is oxidised into acetate what is reduced
NAD
What is the name of the enzyme that oxidises pyruvate into acetate
Pyruvate dehydrogenase
When pyruvate is oxidised acetate, what is produced
A molecule of carbon dioxide
What combines with acetate to form acetyl Co-A
Co-enzyme A
How many carbons are in acetate
2
How many carbons are in pyruvate
3
How many carbons are in Acetyl Co-A
2
What is Co-enzyme A not
An enzyme
What is Co-enzyme A used for
To help regulate enzymes and to activate enzymes so they can function
What type of enzymes are involved in the Krebs cycle
Dehydrogenases
The Krebs cycle involves a series of what
Oxidation & decarboxylation reaction
What are the products of the Krebs cycle
- x1 ATP
- x2 carbon dioxide
- x3 NADH2
- x1 FADH2
The ATP produced in the Krebs cycle is produced by type of phosphorylation
Substrate level phosphorylation
In the Krebs cycle, what does the 4 carbon molecule combine with the make the 6 carbon molecule
Acetyl Co-A
When the 6 carbon molecule becomes the 5 carbon molecule in the Krebs cycle, what is released from the cycle and what is the name of the process
- Carbon dioxide is released
- It’s known as decarboxylation
When the 6 carbon molecule becomes the 5 carbon molecule in the Krebs cycle, what is reduced
NAD
When the 5 carbon molecule becomes the 4 carbon molecule, what is released
- Carbon dioxide
When the 5 carbon molecule becomes the 4 carbon molecule in the Krebs cycle, what 2 things are reduced
- NAD
- FAD
When the 5 carbon molecule becomes the 4 carbon molecules in the Krebs cycle, what is synthesised
ATP from ADP and Pi (by substrate level phosphorylation)
Why does the electron transport chain occur in the inner mitochondrial membrane
It’s the location of the electron carriers, proton pumps and ATP synthesis
The electron transport chain involves a series of _______ reactions
Redox
In the electron transport chain, what 2 molecules provide the protons and high energy electrons
- NADH2
- FADH2
NADH2 and FADH2 are _______ releasing ______ and high energy _______
- Oxidised
- Protons
- Electrons
What happens to the electrons as they pass along a chain of electron carriers
They lose energy
When the electrons lose energy being passed along a series of electron carriers, what is the energy used for in the electron transport chain
To pump protons from the matrix into the intermembrane space
What is generates after the protons have been pumped from the matrix to the intermembrane space
A concentration gradient
Once a concentration gradient has been established between the matrix and the intermembrane space, what happens to the protons, name the process
Protons move back into the matrix by faciliatated diffusion via ATP synthease
When the protons move back into the matrix via ATP synthease, what can then be synthesise, and what type of phosphorylation is it
- ATP can be synthesised from ADP and Pi
- By oxidative phosphorylation
How many ATP molecules are made from each NADH2
3
How many ATP molecules are made from each FADH2
2
What is the role of oxygen in the electron transport chain (4 points)
- Oxygen is the terminal electron acceptor
- In the electron transport chain
- It accepts protons and electrons
- And is reduced to water
Describe the process of glycolysis (4 marks)
- Phosphorylation of glucose by ATP
- Oxidation of triose phosphate to pyruvate
- Net gain of ATP
- NAD reduced
Melonate inhibits a reaction in the Krebs cycle. Explain why malonate would decrease the uptake of oxygen in a respiring cell (2 marks)
- Less/ no reduced NAD / coenzymes
OR - Fewer hydrogens/ electrons removed
- Oxygen is the terminal electron acceptor
In anaerobic respiration, what is not present
Oxygen
In anaerobic respiration, since no oxygen is present, what is also not present
The final electron acceptor
Without the final electron acceptor in anaerobic respiration, what cannot happen
The hydrogen carriers cannot be re-oxidised
When the hydrogen carriers are not re-oxidised in anaerobic respiration, what is the knock on effect
The hydrogen carriers can not be reduced in the link reaction or in the Krebs cycle
What process can still occur in respiration even in anaerobic conditions
Glycolysis
Under anaerobic conditions, in animals, how can glycolysis still occur
Since pyruvate can be reduced into lactate which simulaneously oxidises reduced NAD
Under anaerobic conditions, in plants and fungi, how does glycolysis still occur
Since pyruvate is decarboxylated into ethanal
- Ethanal is then reduced into ethanol which simultaneously oxidises reduced NAD
How many molecules of ATP does aerobic respiration produce
38
How many ATP molecules does anaerobic respiration produce
2
Other than glucose, what 2 other molecules are alternative respiratory substrates
- Lipids
- Proteins
When lipids are used as the respiratory substrate, what is the first step
The lipid is hydrolysed into glycerol and fatty acid chains
After the hydrolysis of the lipid when using lipids as the respiratory substrate, what happens to the glycerol
Glycerol is converted into a 3 carbon sugar and then becomes phosphorylated. The creates triose phosphate which is the oxidised into pyruvate which then enters the link reaction
When using lipids as the respiratory substrate, what happens the the long fatty acid chains
- Chains split into 2 carbon long fragments
- Which are then converted into Acetyl CoA
- Which then enters the Krebs cycle
When using proteins as the respiratory substrate, what is the first step, and what does this step involve
The first step is deamination which involves the removal of the amino group and the hydrogen, so an overall removal of ammonia
After deamination, what is left
An organic acid
Using proteins as the respiratory substrate, following the deamination process, what happens
The organic acid enters the Krebs cycle
Does reduced NAD or reduced FAD release high energy electrons
Reduced NAD
How many hydrogen ions or pumped per proton pump
2 Hydrogen ions
What do stalked particles contain that is used to pump protons
ATP synthase
How many proton pumps does one molecule of reduced NAD activate
3
How many proton pumps does one molecule of reduced FAD activate
2
Why does anaerobic respiration produce far less ATP than aerobic respiration
- Anaerobic respiration relies on substrate level phosphorylation in glycolysis to produce a net gain of 2 ATP per glucose
- Aerobic respiration produce 2 ATP from substrate-level phosphorylation in glycolysis, 2 ATP from substrate-level phosphorylation in the Krebs’ cycle and around 32 ATP fro oxidative phosphorylation
Why is glucose not used as the respiratory substrate for isolated mitochondria (2 marks)
- Glucose is used / broken down during glycolysis / in cytoplasm;
- Accept: glucose to pyruvate or glucose not converted to pyruvate for one mark
- Glucose cannot cross mitochondrial membrane(s) / pyruvate can cross mitochondrial membrane(s);
Without oxygen, less ATP is produced by respiration Explain why. (2 marks)
Oxygen is the termina/ acceptor; (No) electron transfer chain / proton transfer / no oxidative phosphorylation;
Accept ETC abbreviation
Which produces most of the ATP (in aerobic respiration); Only glycolysis takes place; Pyruvate used to make lactate;
Accept lactic acid
Only produces (net) 2 ATP (per molecule of glucose);
Describe how acetylcoenzyme A is formed in the link reaction (2 marks)
- Oxidation of / hydrogen removed from pyruvate and carbon dioxide released;
- Addition of coenzyme A.
Explain why converting pyruvate to lactate allows the continued production of ATP during anaerobic respiration (2 marks)
- Regenerates / produces NAD / oxidises reduced NAD;
- (NAD used) in glycolysis
In muscles, some of the lactate is converted back to pyruvate when they are well supplied with oxygen. Suggest one advantage of this (1 marks)
(Pyruvate used) in aerobic respiration / (lactate / lactic acid) is toxic / harmful / causes cramp / (muscle) fatigue.
Describe the role of mitochondrial cristae in the synthesis of ATP
- The cristae are highly folded, increasing the surface area for ATP synthase by providing more space for electron transfer chains and ATP synthase
- The cristae contain the proteins for the electron transfer chain, where electrons are transferred through redox reactions, releasing energy.
- The electron transfer chain actively pump protons into the intermembrane space, creating an electrochemical gradient necessary for ATP production.
- Protons flow back into the mitochondrial matrix through ATP synthase, during the phosphorylation of ADP to ATP
