ATP, Photosynthesis, Cellular Respiration

Unit 4 Study Guide Cellular Energy: ATP, Photosynthesis, Cellular Respiration Energy Overview • Energy comes in multiple forms o Examples: thermal (heat), radiant (light), kinetic/mechanical (movement), electricity (moving electrons), chemical (stored in bonds between atoms), and more • Law of Conservation of Energy o States that energy cannot be created or destroyed, but only cycles and transfers between different forms o Ex: In photosynthesis, light energy is transferred into electricity in the chloroplast. This electricity is then transformed into chemical energy in the form of ATP and glucose. • ATP (Adenosine Triphosphate) o The cell’s energy molecule o Made of a molecule called adenosine bonded to three phosphate groups o The bond connecting the last phosphate group has the most energy ▪ You break the bond to release energy (A-P-P-P becomes A-P-P + P) and make ADP ▪ You make the bond between ADP and a phosphate group to store energy (A-P-P + P becomes A-P-P-P) Photosynthesis Light • Small particles called photons moving as a wave. • We can detect light in the middle called the Visible Spectrum. We see the visible spectrum as colors. • Light can be absorbed (taken in) or reflected (bounced back). Whatever colors are bounced back to our eyes are the colors we see. Leaves appear green because only green light is reflected back to our eyes. Pigments • Chemicals that can absorb light and capture its energy • Chlorophyll is the plant’s main pigment o It is found inside the chloroplasts, the small organelles found in the cells of leaves. o Absorbs all wavelengths of light except for green. o Captures the sunlight energy so that plants can do photosynthesis. • Plants have other pigments that are not made in significant quantities like chlorophyll - this allows the plant to absorb sunlight from multiple different wavelengths of light Photosynthesis • The way plants and algae make food from sunlight energy and carbon dioxide. • Divided into two parts, the light dependent reactions and the light independent reactions (also known as the Calvin Cycle or the Dark Reactions) 1. Light Dependent Reactions Where? Thylakoid Membrane of the chloroplast in the leaf cells When? Only occurs when light is present Needs? Sunlight, H2O (water) from the roots Makes? O2 (oxygen), ATP What? Light hits the chlorophyll in the thylakoid membrane of the chloroplast. The chlorophyll captures the light energy and uses it to break water apart. When water is broken it forms oxygen gas, hydrogen ions (H+), and electrons. The electrons move through the membrane to produce electrical energy. This electrical energy is used to move all of the H+ to one side of the membrane (creates a concentration gradient). The H+ then flows down their concentration gradient through a special membrane protein called ATP Synthase. The movement of the H+ powers the ATP Synthase to make ATP. 2. Light Independent Reactions Where? Stroma of the chloroplast in the leaf cells When? Any time, even when it is dark outside Needs? ATP from the light dependent reactions, CO2 (carbon dioxide) from the air Makes? C6H12O6 (glucose) What? The ATP made in the light dependent reactions is used to take six individual molecules of carbon dioxide (CO2) and form bonds between them to create the six-carbon glucose molecule. CO2 → C6H12O6 Photosynthesis Equation 6CO2 + 6H2O → C6H12O6 + 6O2 Cellular Respiration and Fermentation • The process of cells turning food (glucose) into energy (ATP) • Every single living thing does some part of cellular respiration. Prokaryotes only perform glycolysis. Eukaryotes (cells with mitochondria) can perform all steps of cellular respiration. Mitochondria Structure Anaerobic vs. Aerobic • • • Some parts of cellular respiration occur with oxygen and some do not need oxygen to occur. Using oxygen allows cells to get more energy, but not all cells can use it. Aerobic means with oxygen o Cells with a mitochondria (eukaryotes like plants and animals) can do this type of respiration o Includes the Citric Acid Cycle and Electron Transport Chain Anaerobic means without oxygen o All cells can do this type of respiration (does not need a mitochondria) o Includes Glycolysis and fermentation Glycolysis What? Split glucose in half to form two molecules of pyruvate. Lysis means break, glycol refers to glucose. Where? Cytoplasm (aka cytosol) of the cell When? Anaerobic – happens any time. Does not need oxygen. Needs? C6H12O6 (glucose), 2 ATP Makes? 4 ATP (2 net ATP), 2 molecules of pyruvate, NADH (to carry electrons around the cell) Citric Acid Cycle What? Breaking pyruvate down to capture energy stored in the bonds. Produces CO2 as a waste product. Happens TWICE! Once for each pyruvate from glucose. Where? Stroma of the mitochondria. When? Aerobic – only happens when oxygen is present. Needs? Pyruvate Makes? 2 ATP, three molecules of CO2, NADH, FADH2 per cycle Since there are two pyruvates per glucose, the final totals per molecule of glucose are: 4 ATP, 6 molecules of CO2 Electron Transport Chain What? Transporting electrons through the mitochondria and capturing their energy to produce ATP. The movement of electrons through the membrane creates a concentration gradient of H+. The electrons are finally captured by O2, converting it into H2O. As the H+ moves down its concentration gradient it power a membrane protein called ATP Synthase to produce ATP. Where? Cristae/Inner membrane of the mitochondria. When? Aerobic – only happens when oxygen is present. Needs? O2 (oxygen) to capture the electrons at the end, NADH/FADH2 from glycolysis and the citric acid cycle Makes? 32 ATP, H2O (water) Cellular Respiration Equation C6H12O6 + O2 → CO2 + H2O + 38 ATP