Respiration Flashcards
(32 cards)
What is respiration?
A set of metabolic reactions that take place in organisms and break down respiratory substances like glucose into smaller inorganic molecules, like water and carbon dioxide.
It is linked to the synthesis of ATP.
Why is respiration described as a catabolic process?
Because complex molecules are broken down into smaller, simpler molecules.
Why do organisms need to respire?
-It produces ATP for a variety of processes
-Releases heat energy for thermoregulation
Define aerobic respiration
Cellular respiration that takes place in the presence of oxygen and produces CO2, water and ATP.
Name the 4 main stages of aerobic respiration
glycolysis, link reaction, Krebs cycle, electron transport chain.
What is substrate level phosphorylation?
Reactions which involve the direct generation of ATP from ADP without using the respiratory chain. This involves the enzyme-catalyzed transfer of a phosphate group from an organic molecule to ATP.
Outline the stages of glycolysis.
- Glucose is phosphorylated to hexose diphosphate by 2 ATP molecules.
- Hexose biphosphate splits into two 3-carbon sugars
- Each of these molecules is oxidized to 2 pyruvate.
Net gain of 2 reduced NAD and 2 ATP per glucose molecule.
Where does glycolysis occur?
In the cytoplasm
How does pyruvate from glycolysis enter the mitochondria?
Via active transport.
What molecule is produced during anaerobic glycolysis from the reduction of pyruvate?
lactate
What is the link reaction?
The process which forms Acetyl CoA from pyruvate for use in the citric acid cycle.
Describe the link reaction
- one molecule of pyruvate is oxidatively decarboxylated and dehydrogenated to make acetate.
- this is then combined with Coenzyme A to produce acetyl CoA
Write an equation to summarize the link reaction
pyruvate + NAD + CoA - acetyl CoA + reduced NAD + CO2
where does the link reaction occur?
In the mitochondrial matrix
What is the Krebs cycle?
A series of oxidation-reduction reactions in the matrix of the mitochondria in which acetyl coenzyme A is oxidised, generating reduced NAD, reduced FAD, ATP and carbon dioxide
What is the function of the Krebs cycle?
It is a means of releasing energy from carbon bonds to provide ATP, reduced NAD and reduced FAD (with the release of CO2)
Where does the Krebs cycle occur?
In the mitochondrial matrix
What is a decarboxylation reaction?
A reaction which removes one carbon and 2 oxygen atoms from a molecule in the form of a molecule of CO2
Briefly outline the process of the Krebs cycle
A series of enzyme catalysed reactions that oxidize Acetyl CoA and produce many reduced cofactors through dehydrogenation reactions.
What is a dehydrogenation reaction?
A reaction where hydrogen is removed from a molecule.
What are the products of the Krebs cycle?
1 ATP (produced by substrate level phosphorylation)
3 reduced NAD
1 reduced FAD
2 CO2
What is the electron transport chain?
A series of electron carrier proteins that transfer electrons in a chain of oxidation-reduction reactions, releasing energy in the form of ATP.
What is ATP synthase?
Enzyme found in the inner mitochondrial membrane which catalyses the formation of ATP from ADP and inorganic phosphate, using energy from chemiosmosis H+ ions.
Define chemiosmosis
The passive diffusion of protons down a concentration gradient across a partially permeable membrane used in oxidative phosphorylation.
