energy transfers in and between organisms (respiration) Flashcards
what are the four stages of aerobic respiration and where do they occur?
-glycolysis - cytoplasm
-link reaction - matrix of the mitochondria
-Krebs cycle - matrix of the mitochondria
-oxidative phosphorylation
outline glycolysis (stage 1)
-a glucose molecule is phosphorylated into glucose phosphate using 2 ATP
-glucose phosphate splits into 2 triose phosphate molecules
-the 2 triose phosphate are oxidised into 2 pyruvate molecules
-this results in a net gain of 2 ATP and and two NADH
outline the link reaction process
- 2 pyruvate molecules are actively transported from the cytoplasm into the mitochondrial matrix
-pyruvate is oxidised into acetate
-2 NAD picks up the hydrogen and becomes 2 reduced NADH
-acetate combines with coenzyme A to form 2 acetyl coenzyme A
outline the krebs cycle
-acetyl co enzyme A reacts with a 4C molecule, releasing co enzyme A and producing a 6C molecule that enters the link reaction
-6C converted to 5C
-decarboxylation and hydrogen removed by NAD to produce reduced NAD
-5C converted to 4C
-decarboxylation and hydrogen removed by NAD/FAD to produce reduced NAD/FAD
-ATP is produced through substrate level phosphorylation
outline the oxidative phosphorylation
-NAD dehydrogenase causes electrons to be released from the the reduced NAD and FAD so they can undergo successive redox reactions as they move along the electron transport chain
-the energy released is coupled to the active transport of protons from the mitochondrial matrix into the intermembrane space , maintaining a proton concentration gradient
-in chemiosmosis, the protons move down their electrochemical gradient into the mitochondrial matrix via the channel protein ATP synthase
-this catalyses the phosphorylation of ADP into ATP
-oxygen in the matrix is the final electron acceptor in the electron transfer chain and produces water as a byproduct.
what happens during anaerobic respiration in animals?
-it occurs only in the cell cytoplasm
-the pyruvate produced in glycolysis is reduced to form lactate by gaining a hydrogen from the reduced NAD
-this oxidises the NAD so that it can be reused in glycolysis and ensure that more ATP can be produced when oxygen is in short supply
-lactate is acidic so decreases the pH and results in muscle fatigue
what happens during anaerobic respiration in microorganisms?
-pyruvate produced in glycolysis is decarboxylated to form ethanal
-ethanal is reduced to ethanol by gaining the hydrogen from the reduced NAD
-this oxidises the NAD so that it can be reused in glycolysis and ensure that more ATP can be produced
-ethanol dissolves the cell membranes and cells die when the ethanol concentration is above 12 percent
compare and contrast anaerobic respiration in yeast cells versus in muscle cells
-both form ATP
-both form pyruvate
-both involve glycolysis
-both form reduced NAD
-ethanol formed by yeast cells whereas lactate is produced by muscle cells
-carbon dioxide is produced by yeast whereas muscle cells do not produce carbon dioxide
explain why an athlete’s ATP is provided by anaerobic respiration rather than aerobic respiration
-high respiration rate
-there is insufficient oxygen in the muscles to aerobically respire
why is a trained organism able to exercise longer than an untrained organism
-adaptions mean more ATP is produced
-anaerobic respiration is delayed
-less lactic acid produced which would cause muscle fatigue
why do athletes breath heavily after a race
-lactate needs to be oxidised into pyruvate to repay oxygen debt
-by aerobic respiration
what are co enzymes
-molecule that aids the functions of enzymes
-by transferring a chemical group between molecules
