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Transcript
Ch.8 – Cellular Energy 8.1 – How organisms obtain energy Energy represents the capacity to do work. Cells must acquire energy from their environment. In life, energy transformations consist primarily of movement of molecules and changes in chemical bonds. Metabolism is the set of chemical reactions that happen in living organisms to maintain life 2 Types Catabolism Releasing energy by breaking down of larger molecules into smaller ones Digestion Anabolism Storing energy by creating larger molecules from smaller ones. Creating body fat Ch.8 – Cellular Energy 8.1 – How organisms obtain energy All living cells use adenosine triphosphate (ATP) for capture, transfer, and storage of energy. Each cell needs millions of ATP molecules per second in order to drive its biochemical machinery Ch.8 – Cellular Energy 8.1 – How organisms obtain energy Autotrophs are able to create glucose from inorganic substances. That glucose is broken down to form ATP molecules Autotrophs Heterotrophs Heterotrophs obtain glucose from digesting other living things. That glucose is broken down to form ATP molecules Ch.8 – Cellular Energy 8.2 – Photosynthesis The story of how living things make ATP starts with… Carbon Dioxide + Water Light Glucose + Oxygen 6 CO2 + 6 H2O Light C6H12O6 + 6 O2 Ch.8 – Cellular Energy 8.2 – Photosynthesis Ch.8 – Cellular Energy 8.2 – Photosynthesis 3PGA Glucose Ch.8 – Cellular Energy Light Reaction Movie 8.2 – Photosynthesis Ch.8 – Cellular Energy 8.2 – Photosynthesis Photosystem II • Light energy is used to split an H2O molecule • When H2O splits - O2 is released - protons (H+ ions) stay in the thylakoid space & - an activated electron enters the electron transport chain. Ch.8 – Cellular Energy 8.2 – Photosynthesis Electron Transport Chain Electrons are moved through the thlakoid membrane and more protons are pumped into the thylakoid space Ch.8 – Cellular Energy Photosystem I •Light reenergizes the electrons •The reenergized electon is transferred to NADP+ Reductase to form an NADPH from NADP+ 8.2 – Photosynthesis Ch.8 – Cellular Energy 8.2 – Photosynthesis Chemiosmosis • Protons build up in the thylakoid space and create a concentration gradient • Protons then move across the thylakoid membrane through ATP synthase which causes ADP to convert to ATP Light Reactions Animation 8.2 – Photosynthesis 1. What is the basic formula of photosynthesis? Ch.8 – Cellular Energy 2. How did plants acquire photosynthesis in evolution? Name three features of chloroplasts that are indicative of their origin. (It is referred to as endosymbiosis or the endosymbiotic theory) Click 3. Photosynthesis can be divided in two different processes. What are these processes? What are their products and reactants? 4. Oxygen is released during photosynthetic light reactions. Where is this oxygen coming from? The splitting of H2O in Photosystem II Ch.8 – Cellular Energy 8.2 – Photosynthesis 5. What is the driving force for ATP synthesis at the ATP synthase multi-protein complex? 6. Where do you find a higher pH value, inside or outside of the thylakoid? 7. Which process creates NADPH from NADP+? Photosystem I Energized e- are transferred to the enzyme NADP+ Reductase Ch.8 – Cellular Energy 8.2 – Photosynthesis Ch.8 – Cellular Energy 8.2 – Photosynthesis The Calvin Cycle (light independent reactions or the dark reactions) 3PGA Glucose Ch.8 – Cellular Energy 8.2 – Photosynthesis Carbon Fixation 3 CO2 combine with 3 5-C compounds to form 6 3-C compounds called 3-PGA Ch.8 – Cellular Energy 8.2 – Photosynthesis Reduction Energy from ATP and NADPH is used to form 6 G3P molecules (high energy molecules) From the 6 PGA molecules 1 G3P molecule leaves the cycle to form glucose, fructose starches, etc. Ch.8 – Cellular Energy 8.2 – Photosynthesis Regeneration ATP and the enzyme rubisco convert the 5 G3P to 3 RuBP These molecules are then ready to bond with 3 more CO2 Calvin Cycle Animation Ch.8 – Cellular Energy 8.3 - Cellular respiration Cellular Respiration Aerobic Respiration requires O2 to make ATP from the energy stored in glucose Glucose + Oxygen Energy + Carbon Dioxide + Water C6H12O6 + 6 O2 36/38 ATP + 6 CO2 + 6 H2O Ch.8 – Cellular Energy 8.3 - Cellular respiration 8.3 - Cellular respiration The 3 Processes of cellular respiration Ch.8 – Cellular Energy O2 2 3 1 Electron Transport Chain Oxidative phosphorylation or Krebs Cycle H2O CO2 2 2 32 Or 34 Ch.8 – Cellular Energy • Glycolysis (“splitting of sugar”) breaks down glucose into two molecules of pyruvate • Glycolysis occurs in the cytoplasm and has two major phases: -Energy investment phase -Energy payoff phase Net ATP = 2 8.3 - Cellular respiration Ch.8 – Cellular Energy Citric Acid Cycle or Krebs Cycle Before the citric acid cycle can begin, pyruvate must be converted to Acetyl CoA It takes place in the matrix of the mitochondria 8.3 - Cellular respiration Ch.8 – Cellular Energy Citric Acid Cycle or Krebs Cycle The acetyl group of acetyl CoA joins the cycle by combining with the 4-C compound, oxaloacetate, forming citric acid (citrate) 8.3 - Cellular respiration Ch.8 – Cellular Energy Citric Acid Cycle or Krebs Cycle The next seven steps decompose the citrate back to oxaloacetate The NADH and FADH2 produced by the cycle send electrons to the electron transport chain 8.3 - Cellular respiration Ch.8 – Cellular Energy 8.3 - Cellular respiration •e- from NADH & FADH2 pass through protein complexes in the cristae (inner membrane) •This causes H+ to be pumped out of the matrix Ch.8 – Cellular Energy 8.3 - Cellular respiration •O the matrix bonds the e- to To2 diffuses give youinto an idea of howand much ATPwith we require passing through the transport survive…chain. + diffuses •H through back thebreath We take in about 2 xATP 1020synthase molecules of Ointo 2 per matrix (chemiosmosis) creating ATP (phosphorilation) 200,000,000,000,000,000,000 8.3 - Cellular respiration Making energy when there is no oxygen Anaerobic Respiration or Fermentation Ch.8 – Cellular Energy It is essentially a cell just relying on glycolysis for its energy needs Only produces 2 ATP per glucose molecule (not the 36 or 38 that aerobic respiration can create) Other molecules are created through reactions that provide the NAD+ needed for glycolysis to occur ATP can be created much faster than with aerobic respiration (just in smaller quantities) Glucose 2 ATP =O -O CH3-C-C-OH 2 Pyruvic Acids Alcoholic Fermentation -O Lactic Acid Fermentation 4 ATP =O -OH CH3-CH 2 Acetylaldehydes CH3-CH-C-OH 2 Lactic Acids CH3-CH2-OH 2 Ethanols Glucose 2 ATP =O -O Lactic Acid Fermentation 4 ATP CH3-C-C-OH 2 Pyruvic Acids =O -OH •Used by some fungi and bacteria & is used to make cheese and yogurt CH3-CH-C-OH 2 Lactic Acids •Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce Glucose 2 ATP =O -O Lactic Acid Fermentation 4 ATP CH3-C-C-OH 2 Pyruvic Acids =O -OH •Used by some fungi and bacteria & is used to make cheese and yogurt CH3-CH-C-OH 2 Lactic Acids •Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce Glucose 2ATP CH3-C-C-OH 2 Pyruvic Acids Used by yeast and some bacteria & is used in brewing, winemaking, and baking Alcoholic Fermentation -O =O -O 4ATP CH3-CH 2 Acetylaldehydes CH3-CH2-OH 2 Ethanols