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Vocabulary Chapter 9 Energy

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1 Vocabulary Chapter 9 Energy
ATP ADP NAD NADP FAD Specific heat capacity Calorie Photosynthesis Light reaction Dark reaction Pigment Chlorophyll Choroplast Photolysis Ribulose biphosphate Phosphoglyceralderhyde Carbon fixation Cellular respiration Anaerobic Aerobic Glycolysis Pyruvate Cytochromes Lactic acid Alcohol Carbon dioxide Fermentation Carotenoids Phycobilins Citric acid Electron transport chain Glucose Kinase Isomerase Vocabulary Chapter 9 Energy

2 Glycolysis

3 The enzyme hexokinase phosphorylates (adds a phosphate group to) glucose in the cell's cytoplasm. In the process, a phosphate group from ATP is transferred to glucose producing glucose 6-phosphate. The enzyme phosphoglucoisomerase converts glucose 6-phosphate into its isomer fructose 6-phosphate. Isomers have the same molecular formula, but the atoms of each molecule are arranged differently. The enzyme phosphofructokinase uses another ATP molecule to transfer a phosphate group to fructose 6-phosphate to form fructose 1, 6-bisphosphate. The enzyme aldolase splits fructose 1, 6-bisphosphate into two sugars that are isomers of each other. These two sugars are dihydroxyacetone phosphate and glyceraldehyde phosphate. The enzyme triose phosphate isomerase rapidly inter-converts the molecules dihydroxyacetone phosphate and glyceraldehyde phosphate. Glyceraldehyde phosphate is removed as soon as it is formed to be used in the next step of glycolysis. Glycolysis steps 1-5

4 The enzyme triose phosphate dehydrogenase serves two functions in this step. First the enzyme transfers a hydrogen (H-) from glyceraldehyde phosphate to the oxidizing agent nicotinamide adenine dinucleotide (NAD+) to form NADH. Next triose phosphate dehydrogenase adds a phosphate (P) from the cytosol to the oxidized glyceraldehyde phosphate to form 1, 3-bisphosphoglycerate. The enzyme phosphoglycerokinase transfers a P from 1,3- bisphosphoglycerate to a molecule of ADP to form ATP. This happens for each molecule of 1,3- bisphosphoglycerate. The process yields two 3-phosphoglycerate molecules and two ATP molecules. The enzyme phosphoglyceromutase relocates the P from 3- phosphoglycerate from the third carbon to the second carbon to form 2-phosphoglycerate. The enzyme enolase removes a molecule of water from 2- phosphoglycerate to form phosphoenolpyruvic acid (PEP). This happens for each molecule of 2- phosphoglycerate The enzyme pyruvate kinase transfers a P from PEP to ADP to form pyruvic acid and ATP. This happens for each molecule of PEP. This reaction yields 2 molecules of pyruvic acid and 2 ATP molecules. Glycolysis steps 6-10

5 Glycolysis literally means "splitting sugars
Glycolysis literally means "splitting sugars." In glycolysis, glucose (a six carbon sugar) is split into two molecules of a three-carbon sugar. Glycolysis yields two molecules of ATP (free energy containing molecule), two molecules of pyruvic acid and two "high energy" electron carrying molecules of NADH. Glycolysis can occur with or without oxygen. In the presence of oxygen, glycolysis is the first stage of cellular respiration. Without oxygen, glycolysis allows cells to make small amounts of ATP. This process is called fermentation. In summary, a single glucose molecule in glycolysis produces a total of 2 molecules of pyruvic acid, 2 molecules of ATP, 2 molecules of NADH and 2 molecules of water. Although 2 ATP molecules are used in steps 1-3, 2 ATP molecules are generated in step 7 and 2 more in step 10. This gives a total of 4 ATP molecules produced. If you subtract the 2 ATP molecules used in steps 1-3 from the 4 generated at the end of step 10, you end up with a net total of 2 ATP molecules produced. For a detailed view of the 10 steps Summary of Glycolysis

6 Glucose & Pyruvate Molecule

7 Transition Rx from pyruvate to acetyl Co A

8 Citric Acid Cycle


10 Photosynthesis is the process of converting light energy to chemical energy and storing it in the bonds of sugar. This process occurs in plants and some algae. Plants need only light energy, CO2, and H2O to make sugar. The process of photosynthesis takes place in the chloroplasts, specifically using chlorophyll, the green pigment involved in photosynthesis. Photosynthesis takes place primarily in plant leaves, and little to none occurs in stems, etc. The parts of a typical leaf include the upper and lower epidermis, the mesophyll, the vascular bundle(s) (veins), and the stomates. The upper and lower epidermal cells do not have chloroplasts, thus photosynthesis does not occur there. They serve primarily as protection for the rest of the leaf. The stomates are holes which occur primarily in the lower epidermis and are for air exchange: they let CO2 in and O2 out. The vascular bundles or veins in a leaf are part of the plant's transportation system, moving water and nutrients around the plant as needed. The mesophyll cells have chloroplasts and this is where photosynthesis occurs. 6H2O + 6CO2  > C6H12O6+ 6O2 Photosynthesis

11 In the Light Dependent Processes (Light Reactions) light strikes chlorophyll a in such a way as to excite electrons to a higher energy state. In a series of reactions the energy is converted (along an electron transport process) into ATP and NADPH. Water is split in the process, releasing oxygen as a by-product of the reaction. The ATP and NADPH are used to make C-C bonds in the Light Independent Process (Dark Reactions). In the Light Independent Process, carbon dioxide from the atmosphere (or water for aquatic/marine organisms) is captured and modified by the addition of Hydrogen to form carbohydrates (general formula of carbohydrates is [CH2O]n). The incorporation of carbon dioxide into organic compounds is known as carbon fixation. The energy for this comes from the first phase of the photosynthetic process. Living systems cannot directly utilize light energy, but can, through a complicated series of reactions, convert it into C-C bond energy that can be released by glycolysis and other metabolic processes. Photosystems are arrangements of chlorophyll and other pigments packed into thylakoids. Many Prokaryotes have only one photosystem, Photosystem II (so numbered because, while it was most likely the first to evolve, it was the second one discovered). Eukaryotes have Photosystem II plus Photosystem I. Photosystem I uses chlorophyll a, in the form referred to as P700. Photosystem II uses a form of chlorophyll a known as P680. Both "active" forms of chlorophyll a function in photosynthesis due to their association with proteins in the thylakoid membrane. Photosynthesis

12 Chloroplast

13 When a photon of light strikes a pigment molecule, the energy is passed from molecule to molecule until it reaches the reaction center which contains a particular form of chlorophyll a. The reaction-center chlorophyll of photosystem I is known as P700 because this pigment is best at absorbing light having a wavelength of 700 nm (the far-red part of the light spectrum). The chlorophyll at the reaction-center of photosystem II is called P680 because its absorption spectrum has a peak of 680 nm (in the red part of the light spectrum). These two pigments, P700 and P680, are actually identical chlorophyll a molecules. However, their association with different protein molecules in the thylakoid membrane accounts for the slight differences in light- absorbing properties. At the reaction center, the absorbed light energy drives an oxidation- reduction reaction (loss and gain of electrons). An excited electron from the reaction-center chlorophyll is captured by a specialized molecule called the primary acceptor. Light drives the synthesis of NADPH2 and ATP, the two main products of the light- dependent reactions, by energizing the two photosystems embedded in the thylakoid membranes of the chloroplast. The removal of hydrogen and electrons from water by photosystem II in the light produces O2, the other major product of the light reactions of photosynthesis. Light reaction

14 Dark reaction ( Calvin Cycle)
Dark reactions don't require light, but they aren't inhibited by it, either. For most plants, the dark reactions take place during daytime. The dark reaction occurs in the stroma of the chloroplast. This reaction is called carbon fixation or the Calvin cycle. In this reaction, carbon dioxide is converted to sugar using ATP and NADPH. Carbon dioxide is combined with a 5-carbon sugar to form a 6- carbon sugar. The 6-carbon sugar is broken into two sugar molecules, glucose and fructose, which can be used to make sucrose. The reaction requires 72 photons of light. Dark reaction ( Calvin Cycle)

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