Energy II Flashcards
what is aerobic respiration and where does it take place?
→Aerobic respiration is the process of producing cellular energy involving oxygen.
→ it occurs ONLY in the presence of oxygen
→ it yields more energy than anaerobic respiration in the form of ATP (around 38)
→it takes place in the mitochondria
what are the steps in the citric acid cycle?
→Pyruvate (3C) is converted to Acetyl CoA (2C), releasing a CO2 molecule and an NADH molecule.
→This is done by the enzyme Pyruvate Dehydrogenase.
→ Acetyl CoA (2C) is then joined with Oxaloacetate (4C) to make citric acid (6C).
→This is done by the enzyme Citrate Synthase.
→ Citric Acid (6C) is then converted to Isocitrate (6C).
→Isocitrate (6C) is then converted to α-ketoglutarate (5C) by Isocitrate Dehydrogenase. This releases a molecule of CO2 and NADH.
→ α-ketoglutarate (5C) is converted to Succinyl CoA (5C) by α-ketoglutarate dehydrogenase. This, again, releases a molecule of CO2 and NADH.
→Succinyl CoA (5C) is converted to Succinate (4C), releasing GTP.
→ Succinate (4C) is then converted to Fumarate (4C), releasing FADH2.
→Fumerate (4C) is converted to Malate (4C).
→ Malate (4C) is finally converted to Oxaloacetate (4C), releasing NADH.
what does pyruvate dehydrogenase do and what is it inhibited and stimulated by?
→converts Pyruvate to Acetyl CoA
→ inhibited by NADH, ATP, Acetyl CoA -
→stimulated by ADP and Pyruvate
what does citrate synthase do and what is it inhibited by?
→joins Oxaloacetate and Acetyl CoA to make Citrate
→ inhibited by citrate
what does isocitrate dehydrogenase do and what is it inihbited and stimulated by
→it converts Isocitrate to α-ketoglutarate
→inhibited by NADH and ATP
→ stimulated by ADP
what does α ketoglutarate dehydrogenase do and what is it inhibited by?
→catalyses the conversion of α-ketoglutarate to succinyl-CoA
→inhibited by NADH, ATP and Succinyl CoA
how many molecules of FADH and NADH and GTP are made in every citric acid cycle?
→FADH2 = 1 →NADH = 3 →GTP = 1
what regulates entry into the citric acid cycle?
→ formation of Acetyl CoA from Pyruvate (by Pyruvate Dehydrogenase) is irreversible.
→This commits the glucose carbon skeleton to either oxidation to CO2 and energy production or fatty acid synthesis.
how is pyruvate dehydrogenase activated in muscles?
→In muscles, Pyruvate Dehydrogenase is activated again via the action of a phosphatase; this enzyme is stimulated by Ca2+ (this increases CoA production)
how do calcium levels increase in the liver?
→In the liver, adrenalin increases calcium through the activation of α-adrenergic receptors and IP3
how is phosphatase stimulated in the liver?
→ In the liver and adipose tissue, insulin (which signifies the fed state) stimulates the phosphatase, which funnels glucose to Fatty Acid synthesis
what is beri beri?
→disease in which the body has a deficiency in thiamine (Vit B1).
→Thiamine is a prosthetic group for pyruvate and α-ketoglutarate dehydrogenase.
→It’s characterised by cardiac and neurological symptoms (impairment of nerves and heart).
→It’s common where rice is a staple.
→Neurological disorders are common as glucose is a primary source of energy.
how many ATP molecules are produced each from NADH and FADH2?
→For every NADH molecule, 3 ATP molecules are formed.
→For every FADH2 molecule, 2 ATP molecules are formed.
how does ATP Synthase generate ATP?
→due to the H+ gradient created, the ions now move back down into the matrix of the mitochondria through ATP Synthase down their electrochemical gradient
→This movement generates enough energy for it to combine ADP and phosphate into ATP.
why do newborn babies need brown fat and where is this distributed?
→newborn babies can’t shiver, so they have brown fat (brown due to the high levels of mitochondria).
→High levels of brown fat in newborns provides an alternative way of regulating heat, to protect them from hypothermia.
→The brown fat is distributed around the shoulders and down the back. As they grow, the amount of brown fat they have decreases.
