Energy is the capacity to perform work

Transcription

1 Energy is the capacity to perform work Two forms Kinetic Heat Light Potential Chemical energy 1

2 Roller Coaster Energy Food, ATP, Chemical Energy 2

3 He s using free energy stored in bonds of food molecules and converting it into work to lift this weight. Is this conversion of free energy into work 100% efficient? First Law of Thermodynamics Energy is TRANSFERRED & not created/destroyed 3

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5 Second Law of Thermodynamics Energy conversions entropy (disorder) Some chem rxns store energy Reactants low in P.E. Products high in P.E. Energy absorbed from env. Where s the energy? Stored in covalent bonds of the product. 5

6 Some chem rxns release energy Reactants high in P.E. Products low in P.E. Energy released from env. Where s the energy? 6

7 Cellular Metabolism Sum total of all chemical reactions in the body (exergonic & endergonic rxns) ATP Used for the work of a cell 7

8 Energy Coupling 8

9 Enzymes Protein molecules Biological catalyst Increases rate of rxn (not a reactant), doesn t add energy to rxn Lowers activation energy Regulates metabolism Specific shape Enzyme Animation 9

10 Factors that affect Enzyme rxns Temperature ph Optimal (humans) degrees Celsius Optimal (for most, NOT all): 6-8 Salt Interferes with chemical bonding Cofactors (sometimes called co-enzyme/vitamins) non-protein helpers Enzyme Virtual Lab 10

11 Enzyme Inhibitors Types: Competitive Binds to active site, blocks enzyme Noncompetitve Binds somewhere other than active site and changes the shape of the enzyme s active site. Enzyme Overview Animation Enzyme YouTube Video How can you overcome it? 11

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13 How does a cell do work? 13

14 May not always be glucose Could be other organic molecules 14

15 Breathing and cellular respiration are closely related 15

16 Cellular respiration banks energy in ATP molecules Cellular respiration is an exergonic process transfers energy in glucose bonds to ATP Cellular respiration produces 38 ATP molecules per glucose Other foods (organic molecules) can be used as a source of energy as well It takes about 10 million ATP molecules per second to power one active muscle cell. The human body uses energy from ATP for all its activities The average adult human needs about 2,000 kcal of energy per day A kilocalorie (kcal) is the quantity of heat required to raise the temperature of 1 kilogram (kg) of water by 1 o C how many calories do you need per day? 16

17 How do cells extract energy from food? Cellular respiration is the controlled breakdown of organic molecules Energy is released in small amounts Gradual release Quick release 17

18 Overview CO 2 + H 2 O Fermentation Lactic Acid or Alcoholic Background information REDOX Reactions Gain of electrons is called reduction Loss of electrons is called oxidation Which was reduced? Which was oxidized? 18

19 Losing Electrons Oxidation, Gaining Electrons Reduction LEO the lion. GER! Examples of Redox Rxn Low electronegativity High Electronegativity Low attraction High attraction High Potential Energy Low Potential Energy ENERGY RELEASED! 19

20 at the H s Glucose loses its H atoms and is converted to CO 2 O 2 gains H atoms and is converted to H 2 O Loss of electrons is called oxidation Gain of electrons is called reduction 20

21 How do we make it gradual? Enzymes and Coenzymes! NAD + Nicotinamide Adenine Dinucleotide Coenzyme [enzyme helper] a.k.a. electron-acceptor or electron-donor Can carry/gain e- From B vitamins (niacin) 1 NADH makes 3 ATP Dehydrogenase Enzyme Transfers H atoms from food to NAD + Dehydrogenase removes 2H from your food Reduced, gained e - Hangs out in solution 21

22 See Respiration HANDOUT Two Mechanisms to Generate ATP 1. Substrate-level phosphorylation 2. Chemiosmosis -- Electron Transport Chain Steps of Cell Resp. 1. Glycolysis & Grooming Stage 2. Krebs Cycle 3. ETC (Electron Transport Chain) 22

23 Glycolysis All cells do it! Ancient process Require enzymes Anaerobic (without O 2 ) Produces 2 2 & 2 See Respiration HANDOUT for details Grooming Stage 23

24 Krebs Cycle (a.k.a Citric Acid Cycle) Where? GOAL: Two cycles per glucose Each turn makes 1 ATP Starts with made from grooming stage produced as a waste 6 & 2 produced for ETC ATP NADH Totals thus far FADH 2 24

25 See Respiration HANDOUT for images ETC (Electron Transport Chain) Where in eukaryotes? Where in prokaryotes? Chemiosmosis occurs H+ increases in conc., increases potential energy Exergonic to endergonic reactions Most ATP made ATP Synthase produced as a byproduct produced to recycle 25

26 Poisons on Cell Respiration 26

27 Fermentation Anaerobic Respiration Without O 2 Alcoholic Fermentation Glycolysis with further reduction Glucose Ethanol + Carbon dioxide 27

28 Lactic Acid Fermentation Ever feel a heaviness in your legs after you sprint? What is that? Glycolysis, no O 2 Pyruvic Acid accumulates and is converted into Lactic Acid. Liver breaks down Lactic Acid back to pyruvate 28

29 Anaerobic Respiration Without Oxygen Anaerobic respiration involves the release of a little energy, very quickly from the incomplete breakdown of glucose without using oxygen, inside the cells. The Process of Anaerobic Respiration 1. Glucose is made available by the breakdown of glycogen stored in the working muscles. Energy for muscles to contract and create movement 2. The glucose Glucose is used by the muscles of the body to produce energy, without the use of oxygen. 3. This process creates lactic Lactic acid, which Acid passes back into the blood for removal. 29

30 Anaerobic Respiration is how sprinters produce the energy that is used in short periods of all out effort - high intensity. Oxygen cannot reach the muscles fast enough, so anaerobic respiration is used. Glucose produces Lactic acid quickly builds up & makes the muscles feel tired & painful. All out effort cannot last for very long! The rest is converted into heat. Some is used for muscle contractions, creating movement. 30

31 Energy and Types of Physical Activities Each physical activity or sport you undertake requires a different energy system Some use mainly aerobic respiration. Others use mainly anaerobic respiration. Most use a combination of the two. Track Events and their use of Aerobic Respiration Event Marathon 10,000 m 5,000 m 1,500 m 800 m 400 m 200 m 100 m Percentage of Aerobic Respiration 100% 95% 83% 60% 50% 20% 10% Less than 1% Basketball players use both systems 31