Photosynthesis and Cellular Respiration - PDF

521 Energy for Cells  Types of Energy Energy Metabolism – The capacity to do work – Light, heat, electrical, etc – Total of all the chemical Potential Energy...

521 Energy for Cells  Types of Energy Energy Metabolism – The capacity to do work – Light, heat, electrical, etc – Total of all the chemical Potential Energy reactions that take place – Stored energy within a cell – Sugar, ATP – Includes all of the building Kinetic Energy up and breaking down of – Energy of Motion substances in a cell Chemical Energy – Relies on chemical energy – Energy stored in bond in the atoms within the cell between molecules – Once bonds are broken the energy is released – Energy in food is stored as potential energy in chemical bonds  Photosynthesis The process by which an organism captures the energy of the sun to convert CO2 and water into glucose https://www.youtubeeducation.c om/watch?v=uixA8ZXx0KU  Photosynthesis Light energy is converted into chemical energy. light 6 carbon dioxide + 6 water → glucose + 6 oxygen or light 6CO2 + 6H2O → C6H12O6 + 6O2  Importance of Photosynthesis 1. It is the chief source of energy on earth. 2. It supplies most of the oxygen found in the atmosphere. 3. It is the first step in food chains.  Who Uses Photosynthesis? Organisms that carry on photosynthesis are called autotrophs or producers. They contain chlorophyll inside cell organelles called chloroplasts. Who Doesn’t Use Photosynthesis? Organisms that are not able to carry on photosynthesis are called heterotrophs or consumers and capture their food. They depend on plants directly or indirectly as their source of food.  Autotroph or Heterotroph Horse Algae Human Cat Corn  Autotroph or Heterotroph Horse heterotroph Algae autotroph Human heterotroph Cat heterotroph Corn autotroph  Chloroplast Energy is put into this system during a ‘Light reaction’ in the Thylakoid. Sugars are created during a ‘synthesis reaction’ that can take place in the dark. ‘dark reaction’ or ‘Calvin Cycle’  What is Light?* Visible light makes up a very small portion of the range of radiations known as the electromagnetic spectrum. – All light travels as a wave that behaves as a particle – Composed of small packets of energy called photons – Wave Model of Light: amount of energy in light is inversely proportional to its wavelength  Photosynthetic Pigments* In order to capture sunlight, plants require special pigments. pigment is any substance that can absorb light. Several types of pigments are necessary to trap the full light spectrum. These pigments consist of colours red, orange, yellow, green, blue, and violet  Pigments - Chlorophyll Two Types: Present in the largest Chlorophyll A numbers compared to – This is the primary other pigments photosynthesis pigment. It directly converts light Capture red and blue light energy to chemical while reflecting green energy. Chlorophyll B Makes leaves appear green – Absorbs light energy and transfers it to chlorophyll A.  Carotene & Xanthophylls Carotenes – Orange in colour Xanthophylls – Yellow in colour Both absorb light in the regions of the colour spectrum not covered by chlorophyll  Light Reaction vs. Dark Reaction Light Reaction (Photo) Dark Reaction (Synthesis) Requires light AKA Calvin Cycle Takes place on the thylakoid Does not require light, but membrane of the chloroplast. does depend upon the high Chlorophyll captures the sun’s energy chemical products energy and uses it to produce made in the light reaction. oxygen and high energy Occurs in the stroma. compounds which are used in Produces glucose the dark reaction. (NADPH, ATP)  Rate of Photosynthesis – 4 Factors 1. Light Intensity 3. Water – The more light, the – when in short supply, more photosynthesis photosynthesis slows down 2. Temperature 4. Minerals – below 0oC and above – When in short supply, 35oC, little photosynthesis slows photosynthesis down  Reactants H 2O CO2 Light NADP+ ADP + P Light Dependent Calvin Reaction Cycle ATP NADPH Chloroplast C6H12O6 O2 Products Glucose  Cellular Respiration This is the process of releasing energy, within a cell, through a complex series of chemical reactions. It occurs in the mitochondria, and consists of the step-by-step breakdown of a nutrient, most commonly glucose, in order to release energy. Glucose is broken down into two three carbon molecules called pyruvate – glycolysis The pyruvate molecules then enter the Kreb’s Cycle  As the carbon molecules move through the cycle, they give off energy. This energy is then stored in the cell in the form of ATP. □ C6H12O6 + 6O2 🡪 6CO2 + 6H2O + ATP glucose + oxygen 🡪 carbon dioxide + water + ATP Steps in Cellular Respiration  Respiration occurs in all cells and can take place either with or without oxygen present. Aerobic Respiration: requires oxygen Occurs in the mitochondria of the cell Total of 36 ATP molecules produced General formula for aerobic respiration: C6H12O6 + 6O2 6 CO2 + 6H2O + 36 ATP glucose + oxygen carbon dioxide + water + energy Human cells contain a specialized structure – the mitochondrion – that generates energy.  Electrons carried in NADH Mitochondria Electrons In Cytoplasm carried in NADH and Glucose Krebs FADH2 Electron Glycolysis Transport Chain Cycle 2 2 32 Summary: st 4 steps: 1 glycolysis 2nd transition stage 3rd Krebs cycle 4th Electron Transport Chain (ETC)  Importance of ATP formation The energy stored in glucose is not readily available to all cell parts, whereas ATP is. Releases energy in the cell with greater control than if the energy came directly from glucose. The ATP acts as the intermediary between energy-releasing (exergonic) and energy-requiring (endergonic) reactions in the cell. What is ATP? Adenosine Triphosphate A high-energy compound found within cells Composed of a molecule of adenosine and three phosphate molecules. – The phosphates are held to the adenosine by high energy bonds The bonds break, releasing energy along with ADP (adenosine diphosphate) and a phosphate  Aerobic vs. Anaerobic Respiration Aerobic Respiration Anaerobic Respiration Glucose is completely oxidized Glucose is broken down in the absence into CO2 and H2O in the presence of oxygen to release energy. of O2 to release energy. Instead of carbon dioxide and water, The most common form of anaerobic respiration produces lactic glucose breakdown. acid Maximum amount of energy to It creates little energy for the cell — 2 be released from the glucose — molecules of ATP 36 molecules of ATP. It occurs in smaller organisms and in Ongoing in all cells most of the larger organisms when oxygen is not time to produce energy. present. It occurs in the cytoplasm of plant and animal cells.  The first step in anaerobic respiration is also glycolysis. Diagram Anaerobic Respiration Cytoplasm Alcoholic fermentation C6H12O6 Bacteria, Yeast 2 ATP glycolysis glucose Lactic acid fermentation Muscle cells 2 ATP Aerobic Respiration Krebs ETC Cycle 36 ATP Mitochondria  Two Anaerobic Respiration Alcohol Fermentation: C6H12O6 2 C2H5OH 2 CO2 (glucose) (ethyl alcohol) + (carbon dioxide) Lactic Acid Fermentation: C6H12O6 2 C 3 H 6 O3 (glucose) (lactic acid)