RESPIRATION Respiration is the process by which the chemical bond energy stored in nutrients is released for use in cells

RESPIRATION

Why do cells need energy? To make new molecules Synthesis and hydrolysis For building membranes and organelles Active transport Muscle contraction\movement Cell division Etc etc

Some facts about respiration: Occurs continuously in all living things Is a series of enzyme controlled reactions May or may not use oxygen Involves the exchange of gases between the organism and the environment The energy in glucose is released when bonds are broken The energy is stored in molecules of ATP

What is ATP??? Just kidding! Don’t use this answer on the regents!!!

What is ATP ? ATP (adenosine triphosphate) is an energy storage compound that stores the energy from glucose and transfers it to other biochemical reactions

When energy is needed by the cell: ATP + H2O ------- ADP + P + energy The enzyme ATP-ase controls the reaction This is a hydrolysis reaction

Two types of Respiration Aerobic Respiration Uses oxygen Occurs in the mitochondria of cells The more energy a cell needs the more mitochondria it will have (for example muscle cells)

Aerobic Respiration Produces 36 molecules of ATP for each molecule of glucose Reactants are oxygen and glucose Products are water, carbon dioxide and ATP

General Equation C6H12O6 + 6O2- 6H2O + 6CO2 + 36 ATP

Two Types of Respiration Anaerobic Respiration Does not require oxygen Occurs in the cytoplasm Used by yeasts and some bacteria Net result of ATP produced is 2 molecules for each molecule of glucose Also called fermentation

Anaerobic respiration Reactant is glucose Products are carbon dioxide and ethyl alcohol or lactic acid

General Equations Glucose-- 2 lactic acid + 2 ATP (occurs in bacteria and muscle cells lacking oxygen) Glucose ----- 2 alcohol + 2 carbon dioxide + 2 ATP ( occurs in yeast cells)

Making bread and alcohol use the process of fermentation

Respiration

Muscle Fatigue If muscle cells don’t have enough oxygen, they will carry out anaerobic respiration This will produce lactic acid and cause sore muscles and muscle fatigue

That was too easy!! C6H12O6 + 6O2- 6H2O + 6CO2 + 36 ATP Even thought the chemical reaction for respiration makes it look simple, it is really a series of complex chemical reactions!

That Was Too Easy! So Put On Your Thinking Caps!

If it were one simple step, all the energy would be released at once and most would be released as heat or light. This would not provide the cell with the continuous supply of energy the it needs.

The Steps of Cellular Respiration: 1. GLYCOLYSIS 2. KREBS CYCLE 3. ELECTRON TRANSPORT CHAIN Helpful information: NAD and FAD are co-enzymes that act as Hydrogen/electron carriers

Glycolysis In this first step, glucose is broken down into to smaller molecules called pyruvic acid ( a 3 carbon sugar)

Glycolysis Glycolysis occurs in the cytoplasm and does not require oxygen This step requires that 2 molecules of ATP be used for activation energy, however 4 molecules are produced, for a net total of 2 from this stage

C6H12O6 = glucose 2 C3H4O3 = 2 pyruvic acids What’s missing? Missing 4 H’s When glucose is broken down into pyruvic acid, 4 extra H’s are picked up by NAD and transferred to other biological pathways

The Krebs Cycle (citric acid cycle) Pyruvic acid is broken down into carbon dioxide (this is what we exhale) in a series of energy extracting reactions Some ATP is produced (2) Additional NADH and FADH2 are formed which carry high energy electrons to the electron transport chain

The Electron Transport Chain The electron transport chain uses the high energy electrons from the Krebs cycle (brought by the NADH and FADH2) to convert ADP to ATP Oxygen acts as the final hydrogen acceptor and combines with 2 hydrogens to make water which is excreted or used for cell metabolism

Heat O2 ATP H2O NAD+ NADH CO2 Glucose ATP Pyruvate MITOCHONDRION Electron Transport System O2 ATP H2O NAD+ NADH CO2 citric acid cycle Glucose ATP Pyruvate ATP MITOCHONDRION

The Totals 1 molecule of glucose produces: Glycolysis= 2 ATP (4 – 2 for activation energy) Kreb Cycle= 2 ATP Electron Transport Chain = 32 For a grand total of 36 molecules of ATP

Is this efficient? Respiration is more efficient than a car engine that burns gasoline! The 36 molecules of ATP that are made from 1 molecule of glucose represent about 38% of the total energy in glucose. What do you think happens to the other 62% It is released as heat