1.7 cellular respiration Flashcards
State the name and location of the three stages that take place during aerobic respiration.
1.Glycolysis – cell cytoplasm
2. Citric Acid Cycle – matrix of the mitochondria
3. Electron Transport Chain – inner membrane of the mitochondria
State the definition of glycolysis.
Glycolysis is the breakdown of glucose to pyruvate, this takes place in the cytoplasm of a cell in both aerobic and anaerobic conditions and releases a net gain of 2 ATP molecules.
Identify the two phases of glycolysis
energy investment phase
energy pay off phase
Describe the energy invesment phases of glycolysis
energy investment phase - During this phase, 2 ATP molecules are required for the phosphorylation of glucose and intermediates.
Describe the energy pay off phase
· energy pay-off phase – During this phase, there is the generation of 4 ATP molecules.
What do the two phases result in
This results in a net gain of 2 ATP molecules during the whole process of glycolysis.
Describe the chemical steps involved in the entry of pyruvate into the citric acid cycle.
At the end of glycolysis, pyruvate, a 3-carbon compound is formed. If oxygen is available (conditions are aerobic), this pyruvate will be broken down to an acetyl group. The acetyl group then combines with a carrier protein called coenzyme A to form acetyl coenzyme A. This molecule is then ready to enter the citric acid cycle.
What is acetyl
Acetyl is a 2-carbon compound and this conversion results in the release of carbon dioxide (CO2) along with hydrogen ions and electrons that are picked up by NAD as it becomes NADH
Name the enzymes that catalyse the removal of hydrogen ions and electrons from substrates during aerobic respiration and state where in a cell this occurs.
The enzymes that catalyse the removal of hydrogen ions and electrons are called dehydrogenase enzymes. They are found in both glycolysis and the citric acid cycle
What happens to NAD during the transport of hydrogen ions and electrons
NAD (oxidised form) becomes NADH (reduced form) as it collects the hydrogen ions and electrons and then returns to NAD (oxidised form) when it releases them into the electron transport chain ready to return to the earlier stages to collect and transport more hydrogen ions and electrons.
What is NAD
NAD is the coenzyme that collects hydrogen ions and electrons for transport to Stage 3 – the electron transport chain.
Stage one of ATP synthesis during the electron transport chain
The electron transport chain is made up of a series of carrier proteins embedded in the inner mitochondrial membrane. One of these carrier proteins is a hydrogen ion pump. NADH releases its hydrogen ions (H+) and electrons (e-) to this carrier protein.
Stage two of ATP synthesis during the electron transport chain
The hydrogen ions are pumped across the inner membrane of the mitochondrion into the inter-membrane space and the high energy electrons are passed on through a series of protein carriers releasing their energy. It is the energy released from the electron transfer that powers the pumping of the hydrogen ions.
Stage three of ATP synthesis during the electron transport chain
As the concentration of hydrogen ions builds up within the inter-membrane space this creates a concentration gradient between the inter-membrane space (high H+ concentration) and the matrix (low H+ concentration). This concentration gradient causes the hydrogen ions to flow back through another of the membrane proteins called ATP synthase.
Stage four of ATP synthesis during the electron transport chain
ATP synthase is an enzyme-complex that results in the production of ATP. As the hydrogen ions flow through the enzyme-complex, ADP is phosphorylated to form ATP.
