CELLULAR RESPIRATION U2 Flashcards
Name the 3 main pathways in aerobic respiration
The three pathways of aerobic respiration are:
Glycolysis
Citric acid Cycle
Electron transport chain
Describe glycolysis and the use of ATP in glycolysis
Glycolysis is the breakdown of glucose to pyruvate.
ATP is required for the phosphorylation of glucose and intermediates during the energy investment phase of glycolysis. (2 ATP)
The leads to the generation of more ATP during the energy pay-off stage (4 ATP) and results in a net gain of ATP (net gain of 2 ATP).
Describe the role of dehydrogenase enzymes and the coenzyme NAD
Dehydrogenase enzymes remove hydrogen ions and electrons and pass them to the coenzyme NAD, forming NADH. This occurs in both glycolysis and the citric acid cycle.
The hydrogen ions and electrons from NADH are passed to the electron transport chain on the inner mitochondrial membrane.
Describe the citric acid cycle
In aerobic conditions, pyruvate is converted into an acetyl group that combines with coenzyme A forming acetyl coenzyme A. NADH and carbon dioxide are also formed during this process.
In the citric cycle, the acetyl group from acetyl coenzyme A combines with oxaloacetate to form citrate. During a series of enzyme-controlled steps, citrate is gradually converted back into back into oxaloacetate which results in the generation on ATP and release of carbon dioxide.
State where glycolysis, the citric acid cycle and the electron transport chain occur
The locations of the stages within the cell are:
Glycolysis – Cytoplasm
Citric acid cycle – Matrix of the mitochondria
Electron Transport chain – Proteins within the inner mitochondrial membrane (Cristae)
Describe the electron transport chain in the synthesis of ATP
The electron transport chain is a series of carrier proteins attached to the inner mitochondrial membrane.
Electrons are passed along the electron transport chain releasing energy.
This energy allows hydrogen ions to be pumped across the inner mitochondrial membrane.
The flow of these ions back through the membrane protein ATP synthase results in the production of ATP.
Finally, the hydrogen ions and electrons combine with oxygen to form water.
State what fermentation is and how much ATP it produces
In the absence of oxygen, fermentation takes place in the cytoplasm.
Fermentation results in much less ATP being produced than in aerobic respiration.
Describe fermentation in animal cells, plant cells and yeast cells
In animal cells, pyruvate is converted to lactate in a reversible reaction.
In plants and yeast, ethanol and carbon dioxide are produced in an irreversible reaction.
State the role of ATP
ATP is used to transfer energy to cellular processes which require energy.
Examples:
Nerve transmission
Muscle contraction
Active transport.
