5.2.2 Respiration COMPLETE Flashcards
DEFINITION- ATP
Energy currency of cells, Adenosine Triphosphate
DEFINITION- Glycolysis
Glucose is broken down into pyruvate
Cytoplasm
DEFINITION- Link Reaction
Pyruvate is actively transported into a mitochondrion and converted into Acetyl Coenzyme A
Mitochondria Matrix
DEFINITION- Oxidative Phosphorylation
Formation of ATP by adding phosphate group to ADP, in the presence of O2
Inner membrane mitochondria
DEFINITION- Oxidation
Loss of electrons
DEFINITION- Reduction
Gain of electrons
DEFINITION- Decarboxylation
Removal of a carboxyl group
DEFINITION- Dehydrogenase
Removal of hydrogen atoms
DEFINITION- ATP Synthase
A channel protein that H+ protons diffuse through, produces the energy to phosphorylate the ATP
DEFINITION- Chemiosmosis
The flow of protons through protein channels (ATP Synthase) down the proton gradient
DEFINITION-Respiration
A process of the energy stored in complex organic molecules being used to make ATP
DEFINITION- Chemical reaction
The energy transferred when bonds are made and broken
ATP Detail
- Phosphorylated nucleotide
- ATP contains energy within bond
- When phosphate is removed from ATP energy is released
- Hydrolysis Reaction
- ATPase enzymes catalyse it
- 0.6KJ is released when phosphate removed
ATP Reaction
ATP + H2O –> ADP + Pi
Steps of Glycolysis
- Activation of glucose by phosphorylation
- Splitting of phosphorylated Hexose Sugar
- Oxidation of Triose Phosphate
- Production of ATP
Activation of glucose by phosphorylation
Glycolysis
- 2 phosphate groups are added to glucose, these come from the hydrolysis of ATP to ADP
- Glucose cannot leave the cell as is too big
Splitting of Phosphorylated Hexose Sugar
Glycolysis
-Hexose biphosphate is split is split into 2 3 carbon sugars called triose phosphate, because its unstable
Oxidation of Triose Phosphate
Glycolysis
- 2 Hydrogen is removed from each triose phosphate molecule (dehydrogenase enzymes)
- The hydrogen is transferred to a hydrogen carrier called NAD to form reduced NAD
Overall Net Products of Glycolysis
2 ATP
2 Reduced NAD
2 pyruvate
Reactions that takes place in the Matrix
- Link Reaction
- Krebs Cycle
Inner membrane Reactions (Mitochondria)
-Where electron transport system is
ATP Synthase Reactions
-Chemiosmosis
Steps of Link Reaction
1.Decarboxylation
2.Dehydrogenation
No ATP is produced, occurs twice for every glucose molecule
Decarboxylation- Link Reaction
The enzyme pyruvate decarboxylase removes the carboxyl group which becomes CO2 and diffuses out the cell. Produces Acetate
Dehydrogenation- Link Reaction
Pyruvate Dehydrogenase removes hydrogen atoms from pyruvate, these reduce the NAD. Produces Acetate
Total Net Products of the Link Reaction
2 Reduced NAD
2 Carbon Dioxide
2 Acetyl Co enzyme A
Final stage of Link Reaction
Coenzyme A reacts with the Acetate to form Acetyl Coenzyme A
Steps of the Krebs cycle
- Acetyl Coenzyme A joins with oxaloacetate to form citrate, releases coenzyme a again
- Citrate is decarboxylated and dehydrogenated, this reduces NAD
- The next 5C intermediate is DeCO2 an deH2 to form.a 4C compound, reduces a NAD
- The 4C compound is converted again and a molecule of ADP is phosphorylated, substrate level phosphorylation
- FAD is reduced as the 4C compound is deH2
- The NAD is reduced by DeH2, the oxaloacetate is regenerated
- Occurs twice for every glucose molecule that enters glycolysis
Total Net products of Krebs cycle
2 ATP
4 CO2
6 Reduced NAD
2 Reduced FAD
Hydrogen Carriers
e.g. FAD and NAD
accept H atoms so they become reduced, they carry the H atoms to the electron transport system for oxidative phosphorylation
Coenzyme A
e.g. Coenzyme A
Carries an acetate group made of pyruvate to the Krebs cycle in the form of acetyl coenzyme A
Oxidative Phosphorylation Steps
- Electron transport chain
- Chemiosmosis
- Oxidative Phosphorylation
Electron Transport Chain
- Hydrogen atoms are removed from reduced NAD and FAD, they’re oxidised
- The hydrogen atoms are split into H+ and e-
- Protons go into the matrix
- The e- are passed along the chain of carriers in the inner mitochondrial membrane under transferred to oxygen
- Oxygen is the final electron acceptor
Chemiosmosis
- Energy is released when e- pass along the electron carrier chain
- This is used to pump protons from the matrix into the inter membrane space
- This builds a proton gradient with a higher conc. in the inter membrane space
- They diffuse through ATP synthase
Oxidative Phosphorylation detail
- As protons flow through ATP synthase enzyme they drive rotation which joins ADP and Pi to form ATP
- At the end of the electron transport chain the electrons combine with hydrogen to form water.
2H+ + 2e- + 1/2O2 –> H2O
OVERVIEW- Glycolysis
USES: 1 Glucose
PRODUCES: 2 ATP, 2 rNAD
OVERVIEW- Link Reaction
USES: Pyruvate
PRODUCES: 2CO2, 2rNAD, 2Acetyl Coenzyme A
OVERVIEW- Krebs Cycle
USES: Acetyl Coenzyme A
PRODUCES: 4CO2, 2ATP, 6rNAD, 2rFAD
OVERVIEW- Electron Transport Chain
USES: 6O2
PRODUCES: 6H20, 34ATP
Reasons why the theoretical amount of ATP generated is higher than the accepted amount
- Some protons leak across the mitochondria membrane
- Some ATP is used to actively transport pyruvate into the mitochondria
- Some ATP is used to transport reduced NAD made in the cytoplasm during glycolysis to e- transport chain
What happens if theres no oxygen
If oxygen is absent then theres no final electron acceptor and no oxidative phosphorylation. Reduced NAD and FAD are not oxidised so not regenerated. Link and Krebs stop.
Alcohol Fermentation
Pyruvate is decarboxylated by pyruvate decarboxylase to form CO2 and Ethanal.
Ethanal accepts 2H from reduced NAD and becomes ethanol, in the presence of ethanol dehydrogenase.
Regeneration of NAD allows glycolysis to continue, net 2 ATP produced in it.
Anaerobic Respiration in Yeast
Alcohol Fermentation
Anaerobic Fermentation in muscles
Lactate Fermentation
Lactate Fermentation
Pyruvate accepts 2H from reduced NAD converting it into lactate, presence of lactate dehydrogenase.
Lactate diffuses into the bloodstream and is taken to the liver where its oxidised back into pyruvate to be repaired again.
Net 2ATP produced in glycolysis.
Substrate Level Phosphorylation
A molecule of ADP is phosphorylated into ATP by the transference of a phosphate group.
Oxygen Debt
O2 is needed to fully oxides the lactate produced during anaerobic respiration. Its converted back into pyruvate using O2 in the liver.
Problems with lactate fermentation
- The reduced ATP produced is not enough
- Lactate causes a fall in pH which leads to proteins denaturing.
Respiratory Substrates
Substrates with more than one hydrogen atom which can be used to generate ATP, more protons for chemiosmosis, so more O2 is required.
Carbohydrates- Respiratory substrate
Broken down into glucose by enzymes for respiration, they enter glycolysis.
Lipids- Respiratory Substrate
Occurs when energy demands are high, triglycerides are hydrolysed by lipase into glycerol and 3 fatty acids.
Glycerol enters glycolysis as Triose Phosphate
Fatty Acids are broken down in mitochondria into fragments that bind to form acetylene co enzyme A which enters the Krebs cycle
Proteins- Respiratory Substrate
Only used in cases of starvation, amino acids are hydrolysed by proteases. The amino acids are deaminated in the liver, and the amino group is converted to ammonia then urea in the ornithine cycle.
Rest of the molecule is converted to pyruvate or acetate and enters Krebs.
More ATP produced from protein.
Energy Value of Carbohydrates
15.8KJ/g
Energy Value of Lipids
39.4KJ/g
Energy Value of Proteins
17.0KJ/g
Respiratory Quotient
RQ= CO2 produced / O2 used
RQ value of Carbohydrates
1
RQ value of Fatty Acids
0.7
RQ value of Amino Acids
0.8
Reason RQ may be greater than 1
If the organism is short of O2 it will respire anaerobically, i.e. in germinating seeds.
Reasons RQ may be low in plants
The CO2 released by the plant is used in photosynthesis
Respirometer
Apparatus used to measure the rate of respiration of living organisms by measuring the exchange of CO2 and O2.
How the Respirometer works
- Contains soda lime to absorb the CO2 so the only change in volume is due to O2 absorption.
- As volume of air reduces in tube, the pressure exerted will be less causing the coloured liquid manometer to rise.
- Initial level and diameter used to work out oxygen absorption in a set time
- Reset system by using syringe to force air back in
- Can be used to find the effect go temperature
Controls with a respirometer
- Find mass when using living organisms
- Allow set time to allow organism to acclimatise
