Cellular Respiration Flashcards
What does ATP break down into?
ADP + Pi (phosphate)
What is phosphorylation?
ATP also has a role in carrying out phosphorylation reactions within living cells. A phosphorylation reaction involves a phosphate group being added to a substrate. This is an enzyme controlled process.
Where does glycolysis take place and does it require oxygen?
Glycolysis takes place in the cytoplasm of the cell and does not require oxygen
Summary of glycolysis?
It is the breakdown, in a series of enzyme-catalysed reactions, of the sugar glucose into two molecules called pyruvate.
What is the energy investment stage and what happens in glycolysis?
to start the process off, energy from two ATP molecules is needed and ATP is used to phosphorylate intermediates in glycolysis
What is energy pay off stage?
The series of reactions eventually produces four ATP molecules, so there is a net gain of two ATP from glycolysis
What else happens in glycolysis with dehydrogenase enzymes?
During the transformation of glucose into pyruvate, dehydrogenase enzymes remove hydrogen ions and electrons that are passed to a coenzyme called NAD which is reduced to form NADH.
What happens if oxygen is present after glycolysis?
If oxygen is present pyruvate progresses to the citric acid cycle.
Where does citric acid cycle take place?
interior matrix mitochondria
Where does the electron transport chain take place?
The inner mitochondrial membrane
Steps of citric acid cycle?
During the citric acid cycle, pyruvate diffuses into the matrix of the mitochondrion, where it is broken down into an acetyl group.
The acetyl group combines with coenzyme A forming acetyl coenzyme A (acetyl CoA).
During the conversion of pyruvate to acetyl coenzyme A, dehydrogenase enzymes remove hydrogen ions and electrons from pyruvate which are passed to the coenzyme NAD, forming NADH.
The acetyl group from acetyl coenzyme A combines with oxaloacetate to form citrate.
During the citric acid cycle, citrate is converted through a series of enzyme-catalysed reactions back into oxaloacetate.
In the process, both carbon (in the form of carbon dioxide) and hydrogen ions (along with electrons) are released.
Hydrogen ions and electrons become bound to NAD to form NADH. NADH will be used in the next stage of respiration to release energy for ATP production.
Carbon dioxide diffuses out of the cell as a waste product and is expired from the organism by breathing out or by diffusion over the body surface.
Steps to the electron transport chain?
Hydrogen ions from NADH are passed onto the etc
The energy is used to pump H ions across inner mitochondrial membrane
Hydrogen ions flow through the ATP synthase protein back through inner mitochondrial membrane and generates ATP
Hydrogen ions combines with electrons and oxygen (final H acceptor) to form water
What is the final acceptor of electrons?
Oxygen is the final electron acceptor, which combines with H ions and electrons, forming water.
What steps need oxygen?
The presence of oxygen is necessary for both the citric acid cycle and the electron transport chain to function. Cell respiration will not occur after glycolysis if oxygen is not present.
What happens if oxygen is not present?
In the absence of oxygen, only glycolysis takes place and pyruvate follows a fermentation pathway in the cytoplasm. Fermentation results in much less ATP being produced than in aerobic respiration.
