Recap: • What is energy? • What do living things use energy for?
Brainstorm Question: If energy cannot be created… then how do organisms acquire energy?
How much energy is in a Snickers bar? Energy is measured in calories. 1 Calorie = the amount of heat required to raise the temperature of 1g of water by 1ºC Q: How do they figure this out for each food?
CHOCOLATE: -high in saturated animal fats (lipids) -high in fructose (carbs) -protein rich (milk) PEANUTS: -high in plant oils (lipis) -high in starch (carbs.) Q: Energy is not listed in the ingredients… CARAMEL: -high in sucrose (carbs) PEANUT BUTTER NOUGAT: -high in oils (lipids) -protein rich (egg whites) -high in sucrose (carbs) …so where is it?
Energy is stored in the chemical bonds of organic molecules. • The highest energy yield comes from fats, carbs and proteins:
How does the body extract the energy from the chocolate bar?
COMBUSTION • Combustion reaction takes place in the body to extract energy from the fuel. • Same reaction that happens in a car engine or a burning candle. Q: Fuel does not spontaneously combust, what else is needed?
Potential energy is stored in the bonds between the atoms. • Breaking these bonds is exergonic, it gives off energy. • The combustion reaction in the body= CELLULAR RESPIRATION • Cellular respiration takes place in every cell in the body.
A closer look… • Fuel alone does not combust (think of a lump of sugar on a plate). Q: What does an engine need to start? Q: What does a match need to burn? Q: What does cellular respiration require other than fuel? • A few different enzymes involved to help extract the most energy from the bonds. a spark + oxygen friction/ heat + oxygen enzymes+ oxygen
Reactants? Products? The Reaction:
If energy is not tangible, how can it be stored? • We don’t use all energy right away • Stored in the body as chemical energy • Cell batteries= molecules ATP ADP= uncharged ATP= CHARGED
ATP molecules are synthesized during cellular respiration. • ATP then used to provide energy for other reactions through out the body. • When charge is drained, ADP is recycled in cells, gets charged again. • Produced in exergonic reactions, used in endergonic reactions. Q: Example of an endergonic reaction where it may be used?
Back to our Snickers bar… • Let’s harvest the energy from a glucose molecule in it… (remember the body will also get energy from the fats and proteins in it, but we will use glucose as an example since it’s body’s main fuel) Q: Glucose does not show up in the ingredients either, where is it?
Where the respiration process takes place STEP 2: KREBS CYCLE STEP 3: ELECTRON TRANSPORT CHAIN STEP 1: GLYCOLISIS Cytosol
Introducing the main players… • Glucose • Oxygen • NAD+/ NAHD • FADH/FADH2 • ADP/ATP • ATPase
Cellular Respiration Role Play • Who will play what molecule • Read the handout with the player info • Familiarize yourself with your role • Get up and find your position around or inside the mitochondria
Basic steps • 1. GLYCOLYSIS (in cytoplasm) • Glucose broken up into 2 3-C molecules (pyruvate) • Some ATP made • H+s and E-s given off from broken bonds loaded onto coenzymes (NAD+ and FADH) • Loaded coenzymes “shuttle” E-s and H+s to mitochondria.
2. KREBS CYCLE (in mitochondrial matrix) • Atoms in the pyruvate molecules go through several rearrangements • Pyruvate molecules get broken down further • More H+s and E-s get loaded onto coenzymes and shuttled away • By product of Cycle is CO2, waste gas
3. ELECTRON TRANSPORT CHAIN (across mitochondrial intermembrane space) • NADH and FADH2 unload electrons into inner mitochondrial membrane • Carrier proteins pass electrons along membrane, creating gradient • H+s get unloaded into inter membrane space • ATPase uses gradient to pump hydrogen atoms across the inner membrane into matrix
ATP Synthase (ATPase) • Acts like a windmill • The movement of protons creates the energy for ATPase to make ATP from ADP+P More detailed ATP Synthase animation ATPase dance (too funny!)
Oxygen then combines with H+s and E-s to create water (byproduct of respiration) • Overview of Respiration video
Lab: Calorimeter • To determine how much energy is in food.
Next up… • Can you respire without breathing? • What is more important for life- oxygen or the sun?
FOOD FOR THOUGHT This special edition Snickers bar is extra “charged”- it contains caffeine, taurineand B-vitamins. How do these ingredients contribute to the energy content of this chocolate bar?
Image Credits • Snickers bar (slide 5)- Flickr (Got Jenna) • Calories graphic (slide 6)- www.deo.ucsf.edu • Respiration graphic (slide 12)- http://bioweb.wku.edu/courses/BIOL115/Wyatt/Metabolism/Respiration.gif • Mitochondria (slide 17)- Public domain (tinojasontran) • TEM human lung tissue (slide 16)- Public domain (Louisa Howard) • Cell (slide 16)- European Bioinformatics Institute • Calorimeter (slide 26)- www.sciencebuddies.com • ATP synthase animation (slide 24)- Dr. Kaiser http://student.ccbcmd.edu/~gkaiser/biotutorials/energy/atpsynthase_an.html permission pending • Snickers Charged (slide 28)- Flickr (the futuristics) • Snickers bar info (slides 4 +15)- www.snickers.com • Clipart (slides 3+26)- Discovery School Clipart gallery