BIO16 Mapua Institute of Technology
The Marathon If somebody challenged you to a run a race, how should you prepare to win? 1. Practice 2. Eat the right foods 3. Drink the right liquids
Energy All living organisms require energy. Sun is source of all energy Through photosynthesis/dark reactions, plants convert solar energy to chemical energy + sugars Other organisms consume sugars, convert sugars to chemical energy Chemical bond energy in food Catabolism of sugars (glucose) is most direct pathway to chemical energy In humans this breakdown usually occurs with oxygen.
Aerobic vs Anaerobic Respiration Aerobic Respiation High energy yield Anaerobic Respiration Low energy yield O 2 as final electron acceptor Occurs in both multicellular and unicellular organisms Organic compounds as final electron acceptor Occurs in anaerobes and in conditions with low oxygen levels
Anaerobic Respiration Glycolysis Formation of fermentation products
Aerobic Respiration Glycolysis Krebs Cycle Electron Transport Chain
The first stage of any respiration pathway
In: Glycolysis - Glucose - 2 ATP - 2 NAD + - 4 ADP Out - 2 Pyruvate - 2 NADPH - 4 ATP - 2 H 2 O - 2 H +
Glycolysis Glucose 2 Pyruvate Occurs in the cytoplasm 2 ATP invested 4 ATP formed by substrate-level phosphorylation = 2 ATP formed in glycolysis Nicotinamide adenine dinucleotide (NAD + ) and flavin adenine dinucleotide (FAD + ) as electron carriers
Anaerobic Pathway
Fermentation General Reaction Glucose + 2 ADP 2 Ethanol + 2 CO 2 + 2 ATP Glucose + 2 ADP 2 Lactate + 2 ATP + 2 CO 2
Preparatory Step
Occurs in the mitochondria Krebs Cycle
Chemiosmosis H + ions are released to the intermembrane space in the ETC H + ion gradient is generated across the inner mitochondrial membrane ATP is generated as the H + ions go down the concentration gradient ATP Generation
ATP synthase generates ATP using the proton gradient
Aerobic Respiration (Overview)
Stage of Respiration Molecules Generated Equivalence Net ATP output Glycolysis [Transition Step] - 2 ATP + 4 ATP x 1 2 ATP 2 NADH 2 FADH 2 x 1.5 3 ATP 2 NADH x 2.5 5 ATP 6 NADH x 2.5 15 ATP Krebs Cycle 2 FADH 2 x 1.5 3 ATP 2 GTP 2 ATP 2 ATP Total 30 ATP
Storing and Using Food Need to generate ATP constantly, can because store food within our cells Fatty acids in fat cells, globules in cells Holds more energy gram for gram than sugar Glucose stored as glycogen, a branched polysaccharide in granules in animal cell cytoplasm Used when not enough glucose in bloodstream Released as glucose 1-phosphate and can enter glycolysis
Sugar Storage in Plants and Mammals
Plants Have chloroplasts as well as mitochondria Mitochondria will generate ATP from the sugars made during photosynthesis Especially in cells without chloroplasts such as roots or when without sunlight Excess sugars can be converted to fats or starch, the equivalent to glycogen in animals, different branching pattern Stored in the chloroplast
Chloroplasts and Mitochondria Chloroplasts make ATP and NADPH that cannot leave ATP and NADPH converted to sugar that can leave and be used in glycolysis and ATP generation in the mitochondria and into other building blocks
Pathway Interactions Some molecule can be substrate in many different pathways Elaborate network of control mechanisms
Bringing It All Together Metabolism High ATP Levels Low ATP Levels Anabolism Catabolism Glycogen Fats Proteins Glycogen Fats Proteins