Flashcards in Respiration, 5.7 Deck (60):
What does respiration release?
Energy - ATP. CO2. Water.
Why is ATP needed?
Drives metabolic reactions. Active transport. Synthesis of molecules. Cell division. Movement.
What is an anabolic reaction?
Builds large molecules
What is a catabolic reaction?
Breaks down large molecules
What does ATP stand for?
When is energy released from ATP?
When its hydrolysed - broken down into ADP + Pi
Does glycolysis need oxygen?
Where does glycolysis take place?
Is glycolysis aerobic or anaerobic?
Describe the stages of glycolysis. Draw a diagram.
1. Glucose is phosphorylated twice to make hexose bisphosphate (6C) - more reactive than glucose
2. Broken down into 2 molecules of TP (3C)
3. Hydrogen removed from TP and passed to NAD to form red. NAD
4. Forms 2 molcules PA/pyruvate - also 4 molecules of ATP
What is the net gain of products from glycolysis?
2 ATP. 2 red. NAD. 2 Pyruvate.
What does NAD stand for?
Nicotinamide Adenine Dinucleotide
What is the role of NAD?
Enzymes that catalyse reduction and oxidation need a coenzyme (NAD) to accept hydrogens. Acts as a shuttle
What is the structure of NAD?
Nicotinamide. Adenine. 5C sugar. 2 Phosphate groups.
Where does pyruvate have to be transported to for the Link Reaction?
The mitochondrial matrix
Describe the stages of the Link Reaction. Draw a diagram.
1. Pyruvate (3C) is decarboxylated and a molecule of CO2 (1C) is released.
2. Pyruvate (3C) is also dehydrogenated, NAD accepts the hydrogen to form red. NAD
3. Produces an acetyl group (2C)
4. Coenzyme A (CoA) combines with the acetyl group to form acetyl CoA
Is the link reaction aerobic or anaerobic?
Aerobic - needs oxygen
What are the products of the Link Reaction?
2 red. NAD. 2CO2. 2 acetyl CoA.
Where does the Krebs Cycle take place?
Is the Krebs Cycle aerobic or anaerobic?
Aerobic - requires oxygen
1. Describe the stages of the Krebs Cycle. Draw a diagram
1. Acetyl combines with oxaloacetate (4C) to form citrate (6C)
2. Citrate is decarboxylated and dehydrogenated to producte 5C compound, CO2 and red. NAD
3. 5C compound is decarboxylated and dehydrogenated to produce a 4C compound
4. 4C compound temporarily combines with CoA, releases ATP from substrate level phosphorylation
4. 4C compound is dehydrogenated to form red. FAD
5. Atoms are rearrange - by isomerase - to form oxaloate
What are the products of the Krebs Cycle per molecule of glucose?
6red. NAD. 2red FAD. 4CO2. 2ATP.
What other substrates can be respired?
Fatty Acids. Glycerol. Amino acids.
How does the electron chain gain electrons?
From red. NAD and red. FAD. Release hydrogen atoms. The hydrogen splits into protons and electrons.
What happens to the electrons?
They pass along a chain of electrons carries in the inner memebrane.
What happens at each protein in the electrons transport system?
1. Each carrier protein has an iron ion
2. The iron ion gains an electron and is reduced
3. It then donates the electron to the next carrier in the chain
How are protons pumped into the intermembrane space?
As electrons pass from one carrier to the next they release some energy which pumps protons
How is ATP generated from protons and the electron transport chain?
1. Protons accumulate in the intermembrane space creating a gradient
2. Generates a chemiosmotic potential/proton motive force
3. Protons diffuse through protein channels associated with ATP synthase
4. Flow of protons changes its shape causing ADP to combine with Pi and produce ATP
What is the role of oxygen in the electron transport chain?
Oxygen acts as the final electron acceptor - it combines with electrons coming off the chain and combines with protons to form H2O.
How many molecules of ATP are made at each stage? And how many in total?
28 - electron transport chain. 2 - Krebs Cycle. 2 - Glycolysis. Theoretically 32 - this is rarely produced
Why is the theoretical yield rarely produced?
ATP required for active transport. ATP required to 'shuttle' red. NAD. Some protons leak out of the outer membrane.
What is the structure of a mitochondria?
Rod shaped. Inner and outer membrane with an intermembrane space. Matrix.
What are specializations of the inner membrane?
Less permeable to hydrogens. Therefore helps to create the proton motive force. Gives a large surface - highly folded. Contains electron carrier proteins.
What are the specializations of the mitochondrial matrix?
Contains: enzymes, mitochondrial DNA, ribosomes, oxaloacetate, molecules of NAD and FAD
What happens if oxygen is absent?
Oxygen cannot act as the final electron acceptor. Conc. of protons increases and proton gradient disappears. Oxidative phosphorylation ceases. Red. NAD and red. FAD can't offload their hydrogen atoms. Krebs cycle and Link Reaction stop.
What is the source of ATP during anaerobic respiration?
Describe the stages of the lactate pathway? Draw a diagram.
1. Pyruvate accepts hydrogen atoms from red. NAD
2. red. NAD is reoxidised an can be reused so glycolysis can continue
3. Pyruvate is reduced to lactate
Where does anaerobic respiration mainly occur?
In mammalian muscle tissue during vigorous activity
What enzyme is used to reduce pyruvate?
How does the body deal with lactate?
Carried away by the blood from muscles to the liver. When more oxygen is available lactate is converted back to pyruvate or recycled to glycogen.
What would happen if lactate was not removed?
The pH in the tissues would be lowered and would inhibit the action of enzymes involved in glycolysis and muscle contraction.
Describe the stages of the ethanol fermentation pathway?
1. Pyruvate decarboxylated and converted to ethanal - by pyruvate decarboxylase
2. Ethanal accepts hydrogen from red. NAD to form ethanol - ethanol dehydrogenase
3. red. NAD is reoxidised and more hydrogen ions can bind to it
What is the main respiratory substance?
How do animals and plants store carbohydrates?
Animals - glycogen. Plants - starch.
What is the mean energy value of carbohydrate?
Why are lipids a good respiratory substrate?
They contain lots of carbons and hydrogen’s which can be used to create ATP
How is a triglyceride broke down?
Hydrolysed to glycerol. Then converted to triose phosphate and respired.
How are fatty acids used in respiration? Describe the process
1. Fatty acid combines with CoA
2. Fatty acid - CoA complex moves to matrix
3. Broken down into two acetyl groups
44. Beta-oxidation pathway generates red NAD and red FAD
What is the mean energy value for lipids?
How are proteins broken down in order to be respired?
Excess amino acids are deanimated in the liver - remove the amino group. The Keto acid enters the respiration pathway as pyruvate or acetyl CoA
What is the mean energy value of a protein?
What does the respiratory quotient show?
How aerobic the respiration is
Using the RQ value how do you know when there is anaerobic respiration taking place?
When it is more than 1. More CO2 produced than O2 consumed.
What is a respirometer?
Measures the rate of respiration by measuring the rate for exchange of oxygen and carbon dioxide.
How does a respirometer work?
1. You need to eliminate one of the variables - use soda lime to absorb CO2
2. Oxygen in the tube absorbed by the organism will therefore be the only volume change of gas
3. As volume of gas decreases pressure on the fluid is less. Pressure from the second chambers will be greater.
4. The fluid in the manometer will therefore move
5. Mark on the positions so you can see how far has moved
Describe the role of ATP in the cell.
- Releases energy
- Phosphates removed by hydrolysis
- Energy used for metabolism
- ADP can attach a phosphate during respiration to form ATP
- Energy release in small quantities
What would be the impact of pyruvate not being transferred into the mitochondrial matrix?
Less pyruvate for Krebs cycle and Link Reaction. No oxidative phosphorylation. Less energy released. Anaerobic respiration would occur
Why is less ATP produced in anaerobic respiration than aerobic respiration?
- Only produced during glycolysis
- Produces a net of 2 ATP
- Only substrate level phosphorylation occurs
- Oxygen can’t be the final electron acceptor
- Krebs Cycle and oxidative phosphorylation do not occur
Why can the anaerobic respiration pathway in yeast not be reversed?
Pyruvate is concerted to ethanol which also produces CO2. Cannot be reversed as the CO2 is lost