2 Chemical Energy & Food One gram of glucose = 3811 calories 1 calorie = amount of energy needed to heat 1 gram of water 1 degree CelsiusFood calories are measured in Calories where 1 Calorie = 1000 calories.What is the difference?
4 Cellular RespirationCellular Respiration is the process that releases energy by breaking down food molecules in the presence of oxygen.6O2 + C6H12O6 6CO2 + 6H2O + EnergyOxygen + Glucose Carbon Dioxide + Water + Energy
5 ATP Adenosine Triphosphate (ATP)—usuable energy form in living things ATP is the important product of cellular respiration.
6 3 Steps in Cellular Respiration Glycolysis—happens in cytoplasmKrebs Cycle—happens in mitochondriaElectron Transport Chain—happens in mitochondria
7 Glycolysis--Step 1Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid (a 3 carbon compound).2 ATP needed to start reaction, 4 ATP are produced thus the net gain is 2 ATP.Does NOT require oxygen
8 Electron CarriersNAD+ (nicotinamide adenine dinucleotide) is an electron carrier used during glycolysisWhen electrons are added to NAD+ it turns into NADH (which holds the electrons until they are needed later on in cellular respiration
9 The Krebs Cycle—Step 2 NEEDS OXYGEN During the Krebs Cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions.Citric Acid is created during the first step of this cycle thus giving it the nickname Citric Acid cycle.Net ATP Production is 2 ATP.
10 Electron Carriers in Kreb’s Cycle NAD+FAD (flavin adenine dinucleotide)When electrons are added to FAD it turns into FADH2Both NADH and FADH2 carry high energy electrons to the electron transport chain
11 Electron Transport Chain—3rd Step The electron transport chain uses the high-energy electrons from the glycolysis and Kreb’s Cycle to convert ADP to ATP.In eukaryotes, high energy electrons are passed along the electron transport chain over a series of carrier proteins on the mitochondrial inner membraneIn prokaryotes this occurs on the cell membraneTotal ATP 32.
12 FermentationReleases energy from glucose without the presence of oxygen.There are two types of fermentation: alcoholic and lactic acid.Alcoholic fermentation is done by yeasts and some microorganisms. It produces alcohol & Carbon DioxideLactic Acid is produced by muscles during rapid exercise when the body cannot supply enough oxygen.
13 Totals Gycolysis 2 ATP Krebs Cycle 2 ATP Electron Transport Chain 32 ATPTotal = 36 ATP
14 Energy & ExerciseQuick energy – Lactic Acid fermentation is used to get quick energy and gives off lactic acid as a by product, thus the muscle pain.
15 Respiration Odds and Ends Fermentation is less efficient than aerobic respiration, but it is fasterFermentation alone cannot keep you alive for long.All fermentation (ethyl alcohol and lactic acid) occurs in the cytoplasmGlycolysis is done by all organisms on Earth
16 Odds and Ends Cont.CO2 is the by-product of respiration. Not all energy in glucose is conereted to ATP, some is lost as heat.Not all cells have the same number of mitochondria. Cells with high energy needs have more. Cells with less don’t do much work.Muscles = lots (100’s or 1000’s)Skin cells = few
17 Odds and Ends ContMost of the energy produced by aerobic respiration is produced by the Electron Transport Chain step.2 ATP’s are needed to start respiration. These are called the activiation energy.