Cellular Respira1on Overview LEARNING GOALS. Stage 1: Glycolysis (Sugar- spli<ng) (10 rxn. s)

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2014-11- 11 Cellular Respira1on Overview LEARNING GOALS By the end of the lesson you will be able to; 1. Describe the diﬀerent stages of cellular respira1on 2.

1 Cellular Respira1on Overview LEARNING GOALS By the end of the lesson you will be able to; 1. Describe the diﬀerent stages of cellular respira1on 2. Understand the process of oxida1ve phosphoryla1on as it relates to cellular respira1on 3. Calculate ATP yield Stage 1: Glycolysis (Sugar- spli<ng) (10 rxn. s) Occurs in cytoplasm; does not req. O2 (i.e. anaerobic) Each rxn. catalyzed by a speciﬁc enzyme Key Facts o Splits carbon backbone in half o 6- carbon glucose molecule à (2) 3- carbon pyruvate (pyruvic acid) molecules o Ini1ally requires an energy investment of 2ATP molecules o Produces 4ATP by substrate- level phosphorylafon for a net of 2ATP produced o Produces 2NADH molecules for further processing o 2 NADH converted to either 2NADH or 2FADH2 in a later process 1

2 Glycolysis alone is not a highly efficient mechanism for harnessing energy. Stored energy in two moles of ATP is 62 kj. But energy that could be released by the complete oxida1on of one mole of glucose is 2870 kj. Therefore glycolysis energy conversion efficiency (per mole of glucose processed) can be represented as follows: For every one mole of glucose, only about 2.2 % of the available free energy is converted to ATP in glycolysis. Some of the energy is lost as thermal energy, but most is s1ll stored in two pyruvate molecules and two NADH molecules, which will con1nue through the subsequent stages of aerobic respira1on. RECALL: up un1l this point, Oxygen has not been necessary! Details to follow The Mitochondria Organelle primarily responsible to synthesizing large quan11es of ATP Label Processes that produce ATP in organelle absolutely REQUIRE O 2 3 steps in cellular respira1on occur in the organelle; pyruvate oxida1on, Kreb s Cycle, Electron Transport Chain & Chemiosmosis Mitochondria has its own DNA (mtdna), RNA, and ribosomes à self- reproduc1on 2

3 Stage 2: Pyruvate OxidaFon (1 rxn.) Occurs in mitochondrial matrix 2 pyruvates moved through both membranes into matrix Key facts o 3- carbon pyruvate molecule à 2- carbon sulfur- containing acetyl- CoA molecule (high energy intermediate) o NO ATP forma1on but one CO 2 and NADH + H produced per pyruvate molecule, therefore, 2CO 2 and 2NADH total 2 molecules of acetyl- CoA enter next stage, Kreb s Cycle, where addi1onal free energy transfer occurs 2 molecules of NADH proceed to Stage 4 to produce ATP by oxida1ve phosphoryla1on 2 molecules of CO 2 diffuse out of mitochon. and then out of cell as low energy waste product (i.e. exhale) 2 H + ions remain dissolved in matrix Acetyl- CoA is a REALLY important molecule in energy metabolism - Why? Details to follow Stage 3: The Citric Acid Cycle aka The Krebs Cycle (8 rxn. s) Occurs in mitochondrial matrix Cyclical; oxaloacetate (product of step 8), is the reactant in Step 1 (Oxaloacetate) + + (Oxaloacetate) Combined, 8 rxn. s result in oxidiza1on of acetyl groups to CO 2, plus synthesis of ATP, NADH, and another nucleo1de- based carrier molecule, FAD/ FADH 2 (flavin adenine dinucleo1de) 3 NADH, 1 FADH 2, 1 ATP (substrate- level phosphoryla1on) per acetyl- CoA molecule that enters Krebs cycle 3

4 The CoA molecule that carried the acetyl group to the cycle is recycled and can par1cipate again in pyruvate oxida1on to pick up another acetyl group. One complete cycle consumes the 2- carbon acetyl unit (amached to CoA) and releases two CO2 molecule, comple1ng the conversion of all the carbon atoms that were originally in the glucose into CO2 By end of Krebs cycle, the original glucose molecule is en1rely dismantled; the six carbon and some oxygen atoms released as six low- energy CO2 waste products All that s len of original glucose is its energy in the form of free ATP and reduced coenzymes, NADH and FADH2. The e- s associated with these H s retain a large amount of chemical poten1al E The E in these reduced coenzymes are transferred o ATP in the next (ﬁnal) stage of cellular respira1on Details to follow NoFce Up, most E stored as carrier molecules, not ATP directly! Why?! Complete the Chart Energy Produc1on Summary ATP NADH FADH2 Stage 1 (Glycolysis) Stage 2 (Pyruvate OxidaFon) Stage 3 (Krebs Cycle) TOTAL ***Stage 4 not included in chart because it is the stage where all carrier molecules are harvested. So no more crea%on of new coenzymes, but conversion of those created into ATP! 4

5 Energy Produc1on Summary Complete the Chart ATP NADH FADH 2 Stage 1 (Glycolysis) Stage 2 (Pyruvate OxidaFon) 2 2* 2* one OR the other, NOT both! Stage 3 (Krebs Cycle) TOTAL 4 10 (or) 8 2 (or) 4 ***Stage 4 not included in chart because it is the stage where all carrier molecules are harvested. So no more crea%on of new coenzymes, but conversion of those created into ATP! Stage 4: Electron Transport Chain & Chemiosmosis (MulFstep) Occurs in the inner mitochondrial membrane & intermembrane space Involves the use of a series of proteins that perfectly illustrate a series of redox reac1ons with oxygen as the final e- acceptor ATP forma1on u1lizes an electrochemical gradient of H + and a special enzyme called ATP Synthase (ATPase) Through a series of steps, all the chemical poten1al E in the carrier molecules, NADH & FADH 2 is harvested to form ATP The 2 NADH molecules created in glycolysis are converted to either NADH or FADH 2 3 ATP/NADH or 2 ATP/FADH 2 Details to follow Aerobic RespiraFon Energy Balance Sheet 5

6 Cellular RespiraFon Summary 6

Cellular Respiration. The Details

Cellular Respiration. The Details Cellular Respiration The Details LEARNING GOALS By the end of the lesson you will be able to; 1. Describe in detail the 4 stages of cellular respira;on 2. Track the crea;on of ATP and energy carrier molecules