CELLULAR RESPIRATION NOTES

CELLULAR RESPIRATION series of oxidative reactions by which cells gradually release energy from glucose and transfer it to molecules of ATP energy that is stored in ATP is immediately available for cellular activities; i.e contracting muscles, passing an impulse along a nerve, or pumping ions by active transport there are two phases; anaerobic (without oxygen) and aerobic (with oxygen)

ATP- ADENOSINE TRIPHOSPHATE special high energy molecule, that stores energy for immediate use consists of adenosine (nucleotide adenine + ribose) + 3 phosphates removal of one phosphate group from ATP --> ADP which is a more stable and lower energy molecule energy is absorbed to add a phosphate to ADP to create ATP STRUCTURE OF THE MITOCHONDRION enclosed by two membranes; outer membrane and inner cristae membrane that is folded inner membrane divides the mitochondria into two internal compartments; outer compartment and matrix Krebs cycle takes place in matrix electron transport chain takes place in outer compartment

ANAEROBIC RESPIRATION (WHEN OXYGEN IS NOT PRESENT)N fermentation **DOES NOT PRODUCE ATP consists of glycolysis + either alcohol fermentation OR lactic acid fermentation 1. Alcohol Fermentation process by which certain cells convert pryruvic acid or pyruvate from glycolysis into ethyl alcohol or carbon dioxide in absence of oxygen2. Lactic Acid Fermentation occurs during strenuous when the body cannot keep up with increased demand for oxygen by skeletal muscles pyruvic acid is produced by glycolysis converts to lactic acid which builds up in muscle which causes fatigue and burning

AEROBIC RESPIRATION (WHEN OXYGEN IS PRESENT) includes 3 processes: glycolysis, the Krebs cycle, and electron transport chain 1. Glycolysis its the anaerobic part of the aerobic respiration 1 glucose breaks into 2 pyruvates pyruvate/pyruvate acid is half of glucose molecule OCCURS IN CYTOPLASM a complex, multi-step process, each step of which is controlled by a enzyme enzyme two molecules of ATP supply energy of activation; the energy needed to begin the reaction releases 4 ATP molecules; resulting in a gain of 2 ATP 1 glucose + 2 ATP --> 2 Pyruvate + 4 ATP + 2 NADH 2. The Krebs Cycle aka citric acid cycle 1st stage of aerobic phase pyruvic acid from glycolysis combines with coenzyme A (a vitamin A derivative) to form acetyl coA, which enters the Krebs Cycle OCCURS IN MATRIX OF MITOCHONDRIA 1 molecule of both ATP and FADH2 + 3 molecules of NADH by-product is carbon dioxide which is exhaled basically it produces a small amount of ATP, carbon dioxide, NADH and FADH2 NADH AND FADH2 molecules that are an important part of cellular respiration coenzymes that shuttle protons and electrons from glycolysis & Krebs cycle to electron transport chain NAD+ is the oxidized form of NADH which is the reduced form. FAD+ is the oxidized form; FADH2 is the reduced form carry H+ protons from Krebs Cycle to ETC each proton carried by an NAD molecule makes 3 ATP and a proton carried by an FAD molecule makes 2 ATP

THE ELECTRON TRANSPORT CHAIN & CHEMIOSMOSIS ETC creates a gradient across the cristae membrane, the gradient is then used to produce ATP through chemiosmosis or oxidative phophlorylation almost all ATP produced during cellular respiration is produced by chemiosmosis PART 1: A Proton Gradient ETC produces a proton gradient NAHD and FADH2 carry out high energy electrons from Krebs Cycle and glycolysis to the ETC, release energy that is used to pump protons (H+) across the cristae membrane which then created the proton gradient gradient represents stored or potential energy that can be used to work just like water behind a dam can be used to produce electricity PART 2: Chemiosmosis uses the stored energy in the proton gradient to convert ADP to ATP and to power synthesis of ATP actual mechanism by which ATP is produced depends on molecule located within cristae membrane; ATP synthase which is actually a channel structure that spins as protons enter the ATP synthase channel, part of the molecule turns and attaches to a phosphate molecule which then turns the once ADP into ATP OXYGEN pulls electrons through ETC and also serves as the FINAL ELECTRON AND PROTON RECEPTOR IN ETC when oxygen combines with protons and electrons at the end of ETC, water is a waste product, this is the water vapor we exhale ETC collection of carrier molecules (cytochromes) embed in cristae membrane every mitochondria has LOTTA ETCs (thousands) ETC carries electrons through a series of redox reactions as special molecules bind to and let go of electrons, in a redox reaction one atom gains elections (reduction) while one atom loses electrons (oxidation) water is produced as a waste product as oxygen combines with protons and electrons that flow dow the ETC proteins cannot diffuse directly through the cristae membrane only through the ATP synthase channel