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- 1. © Cengage Learning 2015 7.7 Can the Body Use Any Organic Molecule for Energy? • Energy from dietary molecules – Aerobic respiration generates a lot of ATP by fully oxidizing glucose, completely dismantling it carbon by carbon • Cells also dismantle other organic molecules by oxidizing them – Complex carbohydrates, fats, and proteins in food can be converted to molecules that enter glycolysis or the Krebs cycle
- 2. © Cengage Learning 2015 Complex Carbohydrates • Starches and other complex carbohydrates are broken down into monosaccharides • Sugars are converted to glucose-6-phosphate for glycolysis – A high concentration of ATP causes glucose-6-phosphate to be diverted away from glycolysis and into the formation of glycogen stores
- 3. © Cengage Learning 2015 Fats • Fats are dismantled by first breaking the bonds that connect the fatty acid tails to the glycerol head • Free fatty acids are oxidized by splitting their backbones into two-carbon fragments – These fragments are converted to acetyl–CoA, which can enter the Krebs cycle • Glycerol gets converted to PGAL, an intermediate of glycolysis
- 4. © Cengage Learning 2015 Proteins • Dietary proteins are split into their amino acid subunits – Ammonia (NH3), formed as a waste product, is eliminated in urine – The carbon backbone is split, and acetyl–CoA, pyruvate, or an intermediate of the Krebs cycle forms – These molecules enter aerobic respiration’s second stage
- 5. © Cengage Learning 2015 7.7 Can the Body Use Any Organic Molecule for Energy? (cont’d.) starch (a complex carbohydrate) glucose
- 6. © Cengage Learning 2015 7.7 Can the Body Use Any Organic Molecule for Energy? (cont’d.) a triglyceride (fat) glycerol head fatty acid tails NADH, FADH2 intermediate of Krebs cycle pyruvate acetyl–CoAacetyl–CoA Food Fats amino acids NADH ProteinsComplex Carbohydrates fatty acids glycerol glucose, other simple sugars 32 PGAL 41
- 7. © Cengage Learning 2015 7.8 Application: Mitochondrial Malfunction • Sometimes when oxygen enters an electron transfer chain, it escapes as a free radical – Free radicals cause damage by oxidizing biological molecules and breaking carbon backbones • Antioxidants in the cytoplasm detoxify free radicals
- 8. © Cengage Learning 2015 Application: Mitochondrial Malfunction (cont’d.) • A genetic disorder or encounter with a toxin can result in a missing antioxidant or defective electron transfer chain – Free radicals accumulate and destroy first the function of mitochondria, then the cell • This tissue damage is called oxidative stress – Hundreds of incurable disorders are associated with such defects • Cancer, hypertension, Alzheimer’s, and Parkinson’s diseases
Editor's Notes
- #6: Figure 7.9 {Animated} A variety of organic compounds from food can enter the reactions of aerobic respiration. A Complex carbohydrates are broken down to their monosaccharide subunits, which can enter glycolysis (1).
- #7: Figure 7.9 {Animated} A variety of organic compounds from food can enter the reactions of aerobic respiration.