A Closer Look at Cellular Respiration Chapter 9 continued

Steps in Aerobic Respiration 1. Glycolysis (yields 2 ATP) 2. Krebs Cycle (yields 2 ATP) 3. Electron Transport Chain (32 ATP) About 38% of glucose’s energy is released. Remaining 62% lost as heat. More efficient than typical car engine.

Glycolysis (cytoplasm of cell) 2 ATP are spent to split a 6-carbon glucose molecule into 2 3-C molecules. Those molecules are converted to pyruvic acid. 4 ATP and 2 NADH are produced.

Krebs Cycle (matrix of mitochondrion) Pyruvic acid (3-C) loses a carbon, forming CO2; 1 NADH produced. Remaining 2-C join with Coenzyme A, to form acetyl-CoA. 2-C leave the acetyl-CoA to join with 4-C, forming citric acid. CO2 and NADH formed again twice, leaving a 4-C molecule which continues in the cycle; 1 ATP, 1 FADH2, and another NADH formed.

Electron Transport Chain (inner membrane of mitochondrion) NADH and FADH2 lose high energy electrons to carrier proteins; hydrogen ions pumped across membrane and water is formed. H+ ions diffuse back through a special membrane protein (ATP synthase), forming ATP.

Anaerobic Pathways Cells can still release energy from sugars without adequate oxygen -- fermentation. Starts with glycolysis (glucose split into 2 pyruvic acids). Pyruvic acid  ethanol + CO2 -OR- Pyruvic acid  lactic acid 2 ATP released by fermentation.

Glucose, Glucose http://www.science-groove.org/Now/Glucose.mp3 Glucose -- ah, sugar sugar -- You are my favorite fuel From the blood-borne substrate pool. Glucose -- monosaccharide sugar -- You're sweeter than a woman's kiss 'Cause I need you for glycolysis. I just can't believe the way my muscles take you in. (For you, they'll open the door.) All it takes is a little bit of insulin (To upregulate GLUT4).

Ah, glucose -- ah, sugar sugar -- You help me make ATP When my predators are chasing me. Ah, glucose -- you're an aldehyde sugar, And you're sweeter than a woman's kiss 'Cause I need you for glycolysis. I just can't believe the way my muscles break you down. (My glycogen is almost gone.) A few more seconds and I'll be rigor mortis-bound. (Acidosis done me wrong.)

Your sweet is turning sour, baby. I'm losing all my power, baby Your sweet is turning sour, baby. I'm losing all my power, baby. I'm gonna make your muscles ache. No, no, no! I'm swimming in lactate, baby. Yes, I'm swimming in lactate, baby. Now I'm drowning in lactate, baby. I'm gonna make your muscles ache. No, no, no! I'm drowning in lactate, baby.

Ah, glucose -- ah, sugar sugar -- I used you up and you left me flat; Now I'll have to get my kicks from fat. Oh, glucose, glucose, sugar, sugar, The honeymoon is over now.