Glycolysis and Kreb Cycle Essay example

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Glycolysis (First Step) Non-dependent on presence on oxygen (works regardless)
A series of chemical reactions in cytoplasm of a cell
Glucose split in half (Small amount of energy is released and captured in ATP)
Glucose = completely broken down and used to produce more ATP (Cellular Respiration)
Two distinct phases
Uphill = preparatory phase (input 2 ATP = endergonic)
Downhill = payoff
Glucose has a lot of potential energy
Energy in glucose is not readily released unless energy from ATP is first added
When ATP is added, resulting sugar molecule has two phosphate groups = less stable = ripe for chemical breakdown
Payoff = three reactions now yielded energy
Reaction 1 = 1 each half of glucose is attached to high energy phosphate group donates high energy electrons + protons (H+) TOWARDS electron carriers (NAD+) = high electron carriers for greater energy payoff later in cellular respiration
NAD+ NADH, NADH has one additional H+ plus 2 e-
Energy from broken glucose bonds are quickly recaptured by attaching phosphate groups to molecules to ADP = ATP
Two molecules of water are produced
Towards the end… Two ADP molecules take remaining phosphate groups and forms two additional ATP.
Molecule of glucose is broken down into two molecules of pyruvate.
Glycolysis >>> 2 NADH and 4 ATP molecules
2 ATP molecules >>> glycolysis
2 ATP + 2 NADH / glucose molecule
However, the pyruvate STILL contains a lot of energy. Krebs Cycle (Second Step)
Second step and picks up from glycolysis
Pyruvate = 3 carbon ( half of original glucose molecule that was broken down in glycolysis)
In mitochondria
Pyruvate (3 carbons) + NAD+ >>> CO2 and exhaled (1 carbon exhaled. 2 carbon left)
Pyruvate modified (becomes 2 carbon molecule) + coenzyme A (speed up reactions) = bonds start to get broken and energy is released.
The energy released is "grabbed" by NAD+
H+ and e- attach to NAD+ high energy electron carrier NADH = acetyl-CoA
Two pyruvate emerge from glycolysis therefore, two acetyl-CoA molecules and 2 NADH are formed
Acetyl-CoA + H2O + oxaloacetate (joins with the 4 carbon atoms from the original 6) = 1) molecule with 6 carbon atoms
6 carbon
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