G6P G6P G6P OXIDATIVE NADPH (NADPH co, 2 (NADPH PHASE 6PG 6PG RUSP NADPH NADPH F6P GAP co, RUSP RUSP FBP Glycolysis NONOXIDATIVE PHASE DHAP GAP R5P 2 (ATP G6P Nucleotides Pyruvate GAP F6P co, (a) Nucleotide synthesis. When the primary need is for nucleotide biosynthesis, the primary product is ribose-5-phosphate. Acetyl-CaA DHAP FBP Citric acid cycle (b) NADPH synthesis. When the primary need is for reducing power (NADPH), fructose FADH co, phosphates are reconverted to glucose-6-phosphate for reaxidation in the oxidative phase. (NADH ABBREVIATIONS G6P = glucose-6-phosphate 6PG = 6-phosphogluconate RSP = ribose-5-phosphate RUSP - ribulose-5-phosphate GAP = glyceraldehyde-3-phosphate F6P = fructose-6-phosphate DHAP = dihydroxyacetone phosphate FBP = fructose-1,6-bisphosphate (b) Energy generation. When only moderate quantities of pentose phosphates and NADPH are needed, the pathway can also be used to supply energy, with the reaction products being oxidized through glycolysis and the citric acid cycle.

A few hours after the death of an animal, the corpse will stiffen as a result of continued contraction of muscle tissue (this state is called rigor mortis). This phenomenon is the result of the loss of ATP production in muscle tissue.(a) Consult as shown and describe, in terms of the six-step model of muscle contraction, how a lack of ATP in sarcomeres would result in rigor mortis.(b) The Ca2+ transporter in sarcomeres that keeps the [Ca2+]∼10-7 Mrequires ATP to drive transport of Ca2+ ions across the membrane of thesarcoplasmic reticulum. How would a loss of this Ca2+ transport functionresult in the initiation of rigor mortis?(c) Rigor mortis is maximal at ∼12 hrs after death and by 72 hrs is nolonger observed. Propose an explanation for the disappearance of rigormortis after 12 hrs.

Like all chemical reactions, the glycolytic pathway can be expressed as a balanced equation showing reactants on the left side of the equation and products on the right. The equations below describe (a) aerobic glycolysis and (b) anaerobic glycolysis (lactic acid fermentation). However, they are not balanced (i.e., they lack the correct stoichiometry). Complete the equations using the correct stoichiometry, assuming that each reaction starts with one molecule of glucose. glucose + ADP + Pi + NAD+ --> pyruvate + ATP + NADH + H+ glucose + ADP + Pi --> lactate + ATP