Respiration Flashcards
Define respiration
The process of creating ATP from energy stored in complex organic molecules
Define energy
The ability to do work
Why do we need energy
All living organisms needs energy for their biological processes
Identify 3 metabolic processes
- Active transport of substances
- Secretion
- Endocytosis
- Synthesis of large molecules
- Replication of DNA
- Movement
What is a phototroph
An organism which uses sunlight energy to make organic molecules containing chemical potential energy
What is ATP
Adenosine Triphosphate
A phosphorylated nucleotide
High energy compund
Universal energy currency
What type of reaction can break down an ATP molecule
Hydrolysis
What enzyme and products does the hydrolysis reaction of ATP use/produce
ATPsynthase or ATPase
ATP –> ADP + Pi
ADP +Pi –> ATP
Define Coenzyme
A non-protein compound that is necessary for the functioning of an enzyme
What are the 4 stages of respiration
Aerobic Glycolysis
The Link Reaction
Krebs Cycle
Oxidative Phosphorylation
Where does each stage take place in the cell
Gly- cytoplasm
Link- mitochondria matrix
Krebs- mitochondria matrix
OP- folded inner membrane of mitochondria
Why are co-enzymes needed
Needed to help with the redox reactions e.g. NAD - NADH
Identify two co-enzymes used in respiration
NAD
Coenzyme A
Briefly summarise glycolysis
The metabolic pathway where each glucose molecule is broken down into two molecules of pyruvate
Describe the process of glycolysis
Glucose --> (ATP) Glucose-6-phosphate --> Fructose-1-phosphate --> (ATP) Hexose 1,6-bisphosphate --> 2 x triose-phosphate --> (2ATP and 2NADH Produced) 2 x intermediaries --> (2ATP Produced) 2 x pyruvate
Define mitochondria
The site of the aerobic stages of respiration
Describe the structure of a mitochondrion
- Matrix
- Intermembrane space
- Cristae
- Inner and Outer membrane (Envelope)
- ATPsynthase
What is chemiosmosis
The movement of ions across a selectively permeable membrane, down their electrochemical gradient
Describe ATP synthesis in a mitochondrion
- The axle rotates the head
- ADP and Pi join to form ATP
- The section of the headpiece undergoes a conformational shape change and ATP is released
Briefly summarise the link reaction
Pyruvate is converted to acetate.
NAD is reduced
What are the 2 enzymes used in the link reaction
pyruvate dehydrogenase
pyruvate decarboxylase
Briefly summarise the krebs cycle
Acetate oxidised to co2.
NAD and FAD are reduced.
ATP is produced.
Oxaloacetate is regenerated
Describe the steps involved in the Krebs Cycle
- Acetate is offloaded from CoA and joins with Oxaloacetate to form citrate.
- Citrate is decarboxlyated and dehydrogenated to form a 5C compound.
- The hydrogen atoms are accepted by NAD, which take them to the Electron Transport Chain
- The Carboxyl group becomes CO2. - The 5C compound is decarboxylated and dehydrogenated to form a 4C compound.
- The 4C compound is changed into another 4C compound, and a molecule of ATP is phosphorylated.
- The second 4C compound is changed into a third 4C compound and a pair of hydrogen atoms are removed, reducing FAD.
- The third 4C compound is further dehydrogenated to regenerate oxaloacetate
How many turns of the krebs cycle is needed for each molecule of glucose?
2.
1 glucose = 2xpyruvate
2x pyruvate= 1 krebs
Briefly summarise oxidative phosphorylation
The formation of ATP and water via the ETC and chemiosmosis
Describe the Chemiosmosis process
- Reduced NAD and FAD donate hydrogen ions, which are split into protons and electrons
- The protons are pumped across the inner mitochondrial membrane
- The hydrogen ions diffuse through ATP synthase
- produces ATP
Evidence for chemiosmosis
- Researchers isolated mitochondria and treated them by placing them in a solution with a very low water potential.
- This meant that the outer membrane ruptured, releasing the contents of the intermembrane space.
- If they further treated these mitoblasts with a strong detergent, they could release the contents of the matrix.
- ATP was also not made if the mushroom-shaped parts of the stalked particles were removed from the inner membrane of the intact mitochondria.
Why is the ATP yield not always met
- Some hydrogens leak across the mitochondrial membrane
- Some ATP is used to actively transport pyruvate into the mitochondria.
- Some ATP is used to bring Hydrogen from reduced NAD made during glycolysis
Define anaerobic respiration
The release of energy from substrates such as glucose in the absence of oxygen
What is the final electron acceptor in OP
oxygen
Name the two methods of the reoxidisation of NAD
Lactate fermentation
Ethanol fermentation
When would Lactate fermentation occur
Vigorous activity e.g. running
Describe the process of lactate fermentation
Pyruvate accepts hydrogen atoms from NADH , which is reoxidised. 7
Pyruvate is reduced to lactate
What happens to the lactate that has been produced
It is taken to the liver and then either:
- converted into pyruvate
- recycled to glucose/glycogen
Describe the process of ethanol fermentation
Pyruvate is decarboxylated to ethanal. Ethanal accepts hydrogen atoms from NADH, which is reoxidised. Ethanal is reduced to ethanol.
Name the three enzymes involved in fermentation reactions
Pyruvate decarboxylase
Ethanol dehydrogenase
Lactate dehydrogenase
