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Chapters 8 & 9 Photosynthesis & Respiration - All living organisms need ENERGY (humans, trees, fish, bacteria) - Cells use energy for everything they do - Where does energy come from? SUN Plants/trees/veggies animals - Our cells get energy from food, all energy originates in the sun. AUTOTROPHS: make their own food by PHOTOSYNTHESIS (plants, some bacteria) HETEROTROPHS: can’t make their own food, get it from other living things (humans, other animals) Which of the following are autotrophs (make their own food from the sun)? Trees Foxes Peas Blueberries Humans Rabbits Deer Roses 1 Humans get energy from food, what is ENERGY? ATP: Adenosine Triphosphate – 3 phosphates ADP: Adenosine Diphospate – 2 phosphates AMP: Adenosine Monophosphate – 1 phosphate Energy is stored inside phosphate bonds of ATP, ADP, & AMP (like electricity is stored in batteries) BREAKING the phosphate BONDS releases ENERGY ATP = full charged battery (3 phosphate bonds that can be broken) ADP = partly charged battery (only 2 phosphate bond) AMP = very little charged battery (only 1 phosphate bond) - Cells make ATP using energy stored in food - Food is broken down into chemicals: Carbs to sugars like glucose. Energy is stored in those bonds forming glucose. - Plants make their own food (glucose) during photosynthesis 2 Ch 8 - Photosynthesis If all energy originally comes from the sun, how does it get into our food (our hamburgers, salads, fries, pasta, etc?) - The answer is Photosynthesis. Plants make their own sugar (glucose) during photosynthesis and then we eat that plant and its glucose, and break apart those glucose bonds to release energy, OR we eat something else that ate the plant and its glucose (ex: we eat the cow that ate the plant) Photosynthesis: process by which green plants use the energy of sunlight to produce glucose (sugar) During photosynthesis, plants soak in sunlight through their leaves, and combine it with water and carbon dioxide (CO2) to make sugar (glucose). That sugar is used as their food supply and can be used to create energy ATP. Luckily for us, during photosynthesis, Oxygen is released as a waste product – and that is the Oxygen we breathe. 3 Formula for Photosynthesis: Water + CO2 + Energy from Sun Glucose (sugar) + Oxygen 6H2O + 6CO2 + Energy from Sun Glucose (C6H12O6) + 6O2 The energy from the sun is stored in the bonds of glucose to be used later by the plant OR animals that feed on the plants. When needed, the glucose is broken down in the process of respiration to release that energy (ATP) stored in glucose bonds. How do plants trap sunlight energy for photosynthesis? Plants have a green pigment called CHLOROPHYLL that absorbs sunlight CHLOROPHYLL is found in CHLOROPLASTS in stacked membranes called thylakoids. In the thylakoids the chlorophyll is arranged in clusters called photosystems. 4 2 Stages of Photosynthesis: Light-Dependent & Light-Independent Reactions Light-Dependent Reactions: requires light from sun - Light is absorbed by chlorophyll to produce high energy electrons in the thylakoid membranes. - These electrons move to an electron transport chain (ETC). As electrons move thru ETC energy is released to form ATP. - At end of ETC more light is absorbed to raise energy level of electrons. These high energy electrons are passed to electron carrier NADP+ to form NADPH. - Electrons removed from chlorophyll are replaced with electrons taken from the splitting of water. Enzymes in chloroplast break apart water to use its electrons leaving hydrogen ions and oxygen ions behind – these OXYGEN ions are released to form most of the oxygen in the atmosphere. Light-Dependent reactions produce: ATP (energy), and highenergy electrons carried by NADPH, and OXYGEN as a byproduct released into atmosphere (how we get our oxygen) 5 Light-Independent reactions: Does not require light - Takes ATP and NADPH produced by the Light-Dependent reactions and stores it in bonds forming glucose - CO2 in the atmosphere is used in a series of reactions called the CALVIN CYCLE to produce glucose (C6H12O6) 6 turns of the Calvin Cycle makes 1 glucose molecule Light-Dependent reactions absorb energy from sun, this energy is then used in the Light-Independent reactions to build high energy bonds of glucose. 6 Chapter 9 – Respiration How do we break apart the glucose sugar to get the energy stored in its bonds? Through the process of RESPIRATION Respiration: process of breaking down glucose to use its high energy electrons to make ATP (energy) When we are hungry, we get weak because we lack energy. We need to eat (take in glucose) so we can break it down and create energy. Food contains chemical energy and when digested the chemical bonds break and release energy for cells to use. Calorie: used to measure energy stored in food Carbs & Proteins = 4000 kilocalories (4 Calories) of energy per gram Fats = 9000 kilocalories (9 C) of energy per gram Glucose bonds in food are broken a little at a time during respiration in the cytoplasm of cells with the help of enzymes. RESPIRATION: breaking down glucose to produce energy. During respiration, glucose and oxygen react to produce ATP (energy). During the reaction CO2 and H2O are released as waste while the ATP is being made Glucose (C6H12O6) + 6O2 6H2O + 6CO2+ 34 ATP (Energy) !! Respiration is the reverse of Photosynthesis !! Photosynthesis: 6H2O + 6CO2 + Energy from Sun Glucose (C6H12O6) + 6O2 7 Glycolysis: process of breaking down glucose Glyco: glucose lysis: break down (lysosomes) Need energy to start glycolysis; requires 2 ATP -Start with Glucose (6 Carbon sugar) -Add 2 phosphates from ATP (turns to ADP) -breaks into two 3 Carbon sugars with a phosphate called PGAL -Add another phosphate to these 2 PGALs -2 NAD+ steals 2 pairs of high energy electrons and H atoms, becomes NADH -4 ADP steal the 2 phosphates and become 4 ATP energy molecules. -NADH gets rid of high-energy electrons by passing them to Oxygen. - Left with two 3 Carbon Pyruvic Acid GLYCOLYSIS – net gain of 2 ATP, 4 NADH that give electrons to O. IF OXYGEN IS NOT PRESENT TO TAKE THOSE ELECTRONS: FERMENTATION TAKES PLACE. 8 FERMENTATION (Anaerobic Respiration): When OXYGEN IS NOT PRESENT. If Oxygen is not present at end of Glycolysis, fermentation occurs. 2 Types of fermentation: 1. Lactic Acid Fermentation: pyruvic acid accumulates due to glycolysis and is converted to lactic acid. Vigorous exercise causes cells to run out of oxygen and fermentation occurs with build up of lactic acid. This build up of lactic acid cause burning or soreness in muscles. 2. Alcoholic Fermentation: Occurs in Yeasts. Pyruvic acid breaks down into alcohol and CO2. The CO2 causes bread to rise, have bubbles, bubbles in beer. Alcohol produced as a byproduct. AEROBIC RESPIRATION: Occurs when OXYGEN IS PRESENT Gylcolysis only produces a net gain of 2 ATP, not much energy. For more energy, the cell turns to Respiration - the reason why we BREATHE in OXYGEN: Respiration: breaking down food in presence of Oxygen to release more energy. - Occurs in Mitochondria (power house) Formula for Respiration: Glucose (C6H12O6) + 6O2 6H2O + 6CO2+ 34 ATP (Energy) After glycolysis the 2 pyruvic acids produced then go through another series of reactions called the KREBS CYCLE to produce more energy. Oxygen is required for these reactions, and that is why we breathe in Oxygen so that it can be used during respiration to help break down food and release its energy. 9 Krebs Cycle 1. One carbon from pyruvic acid breaks off released as CO2 in presence of co-enzyme A. 2. The other carbons join with 4 carbons to make citric acid. 3. Citric acid broken down in series of steps releasing CO2 and high energy electrons go to electron carriers NAD+ and FAD to form NADH and FADH2. 4. NADH and FADH2 take their electrons into mitochondria’s inner membrane and go thru electron transport chain (ETC) 5. ETC: electrons are passed gradually dropping energy level while their energy is picked up by ADP to make ATP. 6. At end of chain, OXYGEN picks up the electrons and 2 H+ ions to make H2O. This is why we breathe in Oxygen, so it can pick up these electrons. H2O and CO2 are released as byproducts. Krebs Cycle 10 CELLULAR RESPIRATION – the whole process of getting energy: Glucose Glycolysis 2 Pyruvic acid + 2 ATP Krebs Cycle & Electron Transport Chain (Oxygen needed here) 34 ATP produced Total energy produced during Respiration = 2 ATP from Glycolysis + 34 ATP from Krebs Cycle & Electron Transport Chain = 36 ATP Oxygen picks up electrons at the end of the Electron Transport Chain, combines with H+ and forms H2O Respiration releases CO2 and H2O while producing the ATP Glucose (C6H12O6) + 6O2 6H2O + 6CO2+ 34 ATP (Energy) ATP SYNTHASE ENZYME: helps turn ADP into ATP energy in the Electron Transport Chain 11 Review Photosynthesis Respiration Autotrophs Heterotrophs & Autotrophs Chloroplasts Mitochondria Reactants: H20 + CO2 + Sun energy Reactants: C6H12O6 + O2 Products: C6H12O6 + O2 Products: H20 + CO2 + 34 ATP Aerobic Respiration – Oxygen present Anaerobic- NO Oxygen = Fermentation 12