energy transfers in and between organisms (respiration) Flashcards

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1
Q

what are the four stages of aerobic respiration and where do they occur?

A

-glycolysis - cytoplasm
-link reaction - matrix of the mitochondria
-Krebs cycle - matrix of the mitochondria
-oxidative phosphorylation

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2
Q

outline glycolysis (stage 1)

A

-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

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3
Q

outline the link reaction process

A
  • 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
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4
Q

outline the krebs cycle

A

-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

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5
Q

outline the oxidative phosphorylation

A

-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.

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6
Q

what happens during anaerobic respiration in animals?

A

-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

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7
Q

what happens during anaerobic respiration in microorganisms?

A

-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

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8
Q

compare and contrast anaerobic respiration in yeast cells versus in muscle cells

A

-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

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9
Q

explain why an athlete’s ATP is provided by anaerobic respiration rather than aerobic respiration

A

-high respiration rate
-there is insufficient oxygen in the muscles to aerobically respire

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10
Q

why is a trained organism able to exercise longer than an untrained organism

A

-adaptions mean more ATP is produced
-anaerobic respiration is delayed
-less lactic acid produced which would cause muscle fatigue

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11
Q

why do athletes breath heavily after a race

A

-lactate needs to be oxidised into pyruvate to repay oxygen debt
-by aerobic respiration

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12
Q

what are co enzymes

A

-molecule that aids the functions of enzymes
-by transferring a chemical group between molecules

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