INTRODUCTION TO CELLULAR RESPIRATION

…Recall First Law of Thermodynamics: Energy cannot be created or destroyed; it must be transferred from one form to another. Second Law of Thermodynamics: Entropy of the universe increases with any change that occurs.

…Recall Redox Rxns in Cellular Respiration: C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + energy Glucose is oxidized to carbon dioxide Oxygen is reduced to water

Cellular Respiration PURPOSE: to generate cellular energy In the form of ATP Process that occurs in all living cells Five parts: 1) Glycolysis: cytoplasm (all cells) 2) Fate of Pyruvate 3) Krebs Cycle: mitochondria (euk) 4) ETC: mitochondria (euk) 5) Chemiosmosis: mitochondria (euk)

Introduction to Glycolysis Glycolysis is the break down of a glucose molecule Glucose is the preferred source Other sugars, lipids and aa can also be used but yield different amounts of ATP Glyco – refers to sugar Lysis – to burst/break down Process is anaerobic – does NOT require O 2

Overall Results 1 molecule of glucose is broken down into 2 molecules of pyruvate (pyruvic acid) 6-carbon sugar  2 (3-carbon sugars, triose) The process yields a NET of 2 ATP Actually yields 4 ATP but 2 are consumed Atoms are re-arranged to provide energy Re-arrangement allows for bonds to be broken with a minimum input of energy

GLYCOLYSIS REACTION Glucose + 2 NAD P i + 2 ADP → 2 pyruvate + 2 NADH + 2H ATP + 2 H 2 Opyruvate Occurs in 10 steps Requires 10 enzymes

NAD + Nicotinamide adenine dinucleotide Coenzyme Electron transporting molecule Oxidizing agent Able to accept H + 2e- and be reduced = NADH Reducing agent Able to give up H + 2e- in NADH  NAD +

Review Questions Where does the glucose come from: For animals? For plants? What is the function of NADH? Where does glycolysis occur? What is the end product of glycolysis? What are the only types of cells that can perform glycolysis? Does glycolysis require oxygen? How does the process yield energy?

Did You Know…? There are 100 TRILLION cells in your body! At any given instant, each cell contains about 100 BILLION ATP molecules! An active muscle cell uses 600 million ATP molecules each minute! For each ATP “the terminal phosphate is added and removed 3 times each minute” (Kornberg, 1989, p. 65).

HOMEWORK Reading: Section 3.2 of Text

Glycolysis – 10 Steps