What kind of runner are you? LONG DISTANCE RUNNING Slow-twitch fibers for repeated long contractions SPRINTING or WEIGHT LIFTING Fast-twitch fibers Contract more quickly and powerfully
What makes these muscle fibers so different? SLOW TWITCH breaks down glucose to get ATP AEROBICALLY (using oxygen) FAST TWITCH breaks down glucose to get ATP ANAEROBICALLY (not using oxygen)
SLOW MUSCLES 1. Thin fibers 2. have many mitochondria Many myoglobin
FAST MUSCLES Thicker fibers Fewer mitochondria Less myoglobin (“white meat)
What happens if not enough oxygen is available? Glucose is not completely broken down and lactic acid is formed (a larger molecule) that makes muscles ache
Big Question for Chapter 6 How do our cells obtain O 2 for cellular respiration and dispose of CO 2 ?
6.1 Breathing Isn’t that how we obtain oxygen? Breathing = taking in oxygen in our lungs and removing carbon dioxide as we exhale
Respiration Really is... Cellular respiration = breakdown of organic molecules (for energy) in the presence of oxygen (in mitochondrion)
6.2 Cellular Respiration C 6 H 12 O 6 + 6O 2 > 6CO 2 + 6H 2 O + ATP
Glucose Bank Break glucose bonds Stored in ATP glucose ATP
Glucose contains Energy: 1 gram glucose = 4 kcal of energy What are kcal? Kilocalories 1 kilocalorie = 1000 calories
6.3 Need heat to stay alive 75% of energy of daily food just to maintain 2,200 kcal of energy per day needed for average adult
Calculate Walking at 3 mph, how far would you have to travel to “burn off” the equivalent of an extra slice of pizza, which has about 475 kcal? HINT: (p. 91) Walking 3 mph consumes per hour 158 kcal 475/158 = 3 hrs. 3 mph X 3 = 9mi
6.4 Just how DO our cells extract energy from organic fuel molecules? The glucose is dismantled and the energy stored in the bonds is carried by electrons.
We don’t see e-, but we see H atoms. C 6 H 12 O 6 + 6O 2 > 6CO 2 + 6H 2 O + ATP (hydrogen atom = one proton and one electron)
What drives this to happen? OXYGEN A strong tendency to pull electrons from other atoms
6.5 Redox Reaction Movement of electrons from one molecule to another is an oxidation- reduction reaction
Redox reaction Oxidation loss of electrons from one substance Loss of H Reduction addition of electrons to another substance Gain of H
"Leo goes Ger” Loss of electrons = oxidation Gain of electrons = reduction
Key Players of Redox Reactions Dehydrogenase Enzyme Remove H atoms NAD+ nicotinamide adenine dinucleotide coenzyme used to shuttle electrons
How NADH becomes a “Hydrogen Carrier” NAD+ + 2H dehydrogenase NADH 2 picks up 2 e- and e- 2H+ and 2e-
Electron Carrier A.k.a. “hydrogen carrier” Empty With e-/H e- NADH NAD+ NADH
p. 93 C 4 H 6 O 5 C 4 H 2 O 5 Oxidized NAD+ NADH Reduced
How do we get energy? Big molecules in food break apart Released electrons carried to NADH Energy to ATP’s You can now use ATP energy
6.6 Which has more energy? NAD+ NADH Why? NADH has picked up an e-
6.6 ETC Electron Transport Chain Pass e- from higher energy to lower energy state NADH brings e- NAD+
ETC ETC Animation (click)ETC Animation Note each carrier molecule has a greater affinity for e- than its uphill neighbor
Where is the ETC? Inner membrane of the Mitochondrion
Sing the ETC Song To the tune of “Buffalo Gals Won’t you Come Out Tonight”?
6.7 Chemiosmosis Movement of solutes across a membrane from where they are MORE concentrated to where they are LESS concentrated. Movement of H+ ions (click here to see the proton H+ pumps)Movement of H+ ions
“Down the Gradient” Note more H+ ions on one side of the membrane Went “against the gradient” and see energy was used to do this
Chemiosmosis Diffusion of excess H+ ions across a membrane from high to low concentration ADP + Pi = ATP
ATP Synthase ATP Synthase Animation (click here to see the ATP synthase move H+ ions “against the gradient”)ATP Synthase Animation ATP Synthase Animation (click here)ATP Synthase Animation
Makes ATP Energy is generated from the movement of H+ ions …enough to cause a phosphate to join ADP to form ATP
Chemiosmosis and ETC working together on inner membrane ETC and Chemiosmosis Together NADH and FADH 2 carry protons (H+) and electrons (e-) to the electron transport chain
Mitochondrion: Site of Cellular Respiration Mitochondrion Cellular Respiration (be sure to see the cool rotating ATP Synthase and the end of the program)Mitochondrion Cellular Respiration
Peter Mitchell (1920 - 1992) Developed the theory of chemiosmosis Nobel Prize 1978
2 Ways to Make ATP Substrate-level phosphorylation does not involve a membrane makes only small amounts of ATP Chemiosmosis diffusion through a membrane of particles produces more ATP
Glycolysis -Breaks down glucose into pyruvic acid -Occurs in cytoplasm -means “splitting of sugar”
Glycolysis Start with 6-carbon glucose and breaks into two 3-carbon pyruvic acid molecules (or pyruvate)
Glycolysis Animation Glycolysis actually has 9 steps…but you only need to learn that these molecules formed between glucose and pyruvic acid are called intermediates
Glycolysis: What do I need to know? Needs 2 ATP to get started Makes 4 ATP Splits glucose into two pyruvates Makes NADH (an e- carrier) NET GAIN 2 ATP’s
But... Pyruvic acid itself does not enter the Krebs cycle
6.10 “Grooming” Pyruvic Acid Haircut and Conditioning “HAIRCUT” As NADH is reduced to NAD+…pyruvic acid is oxidized (carbon atom removed as CO 2 ) “CONDITIONING” Coenzyme A (from B vitamin) joins the 2-c fragmen MAKES-Acetyl Coenzyme A or CoA
6.11 Ready to GO The Acetyl-CoA is now ready to enter the Krebs cycle Hans Krebs (1900-1981) Yeah, he got a Nobel Prize, too
Krebs Cycle Only 2-C of acetyl participates (Coenzyme A is recycled) Occurs in mitochondrial matrix
6.12 Mitochondrion Note many folds (cristae) of inner membrane This increases surface area
Electron Transport Chain in inner membrane of the Mitochondrion
Electron Carriers In Glycolysis NAD+ In Cellular Respiration NAD+ FAD
Final Electron Acceptor Oxygen It is what drives the reaction and pulls the electrons away from their bonds.
Final Products Water (from oxygen and hydrogens) CO 2 when it was pulled out of Krebs cycle ATP formed mostly from chemiosmosis/ETC
6.12 Chemiosmosis/ETC Powers Most of ATP Produced Glycolysis -2 ATP Krebs Cycle - 2 ATP Chemiosmosis/ ETC - 34 ATP NET TOTAL = 38 ATP
Chemiosmosis and ETC H+ ions can only pass through a special port ATP synthase (see knobs on cristae)
ATP synthase As H+ ions move through the ATP synthase port it powers the formation of ADP + Pi to ATP Animation of ATP synthesis in Mitochondria
OVERALL ANIMATION Cellular Respiration Animation and ExplanationCellular Respiration Animation and Explanation
Burn 1 glucose molecule ~ 100 ATP molecules 100% energy released
Glucose in the body Only about 40% goes to use in ATP molecules Rest lost as heat
6.15 YEAST FERMENTATION In yeast, can they make enough energy without oxygen? YES Is this aerobic or anaerobic? anaerobic
Remember the Yeast Lab? Put glucose with yeast and what were the two by- products? Carbon dioxide and ethyl alcohol
What was the side step? NAD+ was replenished The taxi cab loses its e- and is now available to pick up more electrons. If all the taxi cabs are full, the reaction would stop. NAD+
Alcoholic Fermentation Is using yeast or bacteria to convert glucose to alcohol.
Ethanol is Toxic to Yeast So what do they do with it? Yeast release the waste to the surroundings.
What happens if … The yeast makes too much ethanol? They die X
Lactic Acid Fermentation In your muscles As you exercise, lactic acid is formed. You also breath out carbon dioxide.
Where does the lactic acid go? Carried to liver Here lactic acid is converted back to pyruvic acid.
Where is lactic acid used? Commercially: Lactic acid fermentation is used by bacteria in the dairy industry to produce: Cheese and yogurt
Strict Anaerobes Require anaerobic conditions and are poisoned by oxygen Methanogens are strict anaerobes that release methane as a waste product of cellular metabolism. Many live in mud at the bottom of lakes and swamps because it lacks oxygen, and some (enteric bacteria) live in the intestinal tracts of animals
Facultative Anaerobes Can make ATP either by fermentation or by chemiosmosis, depending on whether oxygen is available or not
Facultative Example Vibrio parahaemolyticus - halophilic, facultative anerobic, rod bacterium that causes a foodborne illness known as seafood poisoning.
Making Beer Large fermentation tanks to make beer and wine have a one-way valve so no oxygen gets in…only the carbon dioxide out.
6.13 ROTENONE POISON Binds with first of the proteins of the ETC used to kill insects and fish pests
Cyanide and carbon monoxide bind with third protein of ETC
Antibiotic oligomycain blocks H+ ions through ATP synthase channel Used to combat fungal infections on the skin
Uncouplers Make the membrane of the mitochondrion leaky to H+ ions So…can’t make ATP DNP prescribed as weight-loss pills, but banned
6.14 Review of ATP YIELD (Ideally) Need 4 ATP to start glycolysis Glycolysis makes 2 ATP Krebs Cycle makes 2 ATP ETC/Chemiosmosis makes 34 ATP TOTAL about 38/ molecule of glucose
Where does it all come from? 1 NADH = 3 ATP 1 FADH 2 = 2 ATP