BIOLOGY 111 1st Edition Lecture 12 Outline of Last Lecture I. Energy FlowII. Cellular RespirationIII. Redox ReactionsIV. Pathways of Cellular RespirationV. Cancer CellsVI. Catabolism VII. Feedback Inhibition Outline of Current Lecture I. PhotosynthesisII. Photosynthesis in PlantsIII. Light Reactions and Calvin CycleIV. Nature of SunlightV. PhotosystemsCurrent LecturePhotosynthesis- Converts sunlight to chemical energy that is stored in sugar and other organic molecules- The products of cellular respiration become the reactants for photosynthesis- Electrons are stripped of the water molecule produced in cellular respiration and transferred to CO2 to reduce the carbon to a carbohydrate level - This requires lots of energy- Releases O2 as a byproduct Photosynthesis in Plants- Occurs in the chloroplasts located mostly in the mesophyll cells (of the leaves of plants)- Within the chloroplasts there areThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Thylakoids – third membrane system that segregates the stroma from the thylakoid region within the thylakoid space- Granum – thylakoid sacs are stacked in columns - The stroma – fluid filled region between the thylakoid membrane and inner membrane- Chlorophyll – located in thylakoid membrane and they are what gives plants their green color Light Reactions and the Calvin cycle- The thylakoid region is the site of light reactions inside the chloroplasts- The “photo” part of photosynthesis- Converts solar energy into chemical energy - Light reactions use solar energy to make ATP and NADPH- Water is split to provide electrons and protons and give of O2 as a byproduct - This supplies chemical energy and reducing power to the Calvin cycle- The Calvin cycle occurs in the stroma of chloroplasts- The “synthesis” part of photosynthesis- The calvin cycle incorporates CO2 into organic molecules (carbon fixation) and convert them into sugarNature of Sunlight- Light is an electromagnetic wave- Electromagnetic waves are disturbances of electrical and magnetic fields (not disturbances of the medium through which light travels)- Wavelength – distance between the crests of electromagnetic waves- High energy is associated with shorter wavelengths - Low energy is associated with longer wavelengths- Visible light is 380-750nm in wavelength- Light is either absorbed, transmitted or reflected - When light is reflected off a surface, we see that color (i.e. green light is reflected back off of a plants leaves because the wavelengths associated with green are reflected) - Black light is all absorbed- White is all reflected Photosystems- A photosystem is composed of a reaction center complex surrounded by several light-harvesting complexes.- When a pigment molecule absorbs a photon, the energy transferred from pigment molecule to pigment molecule in like a wave.- They each get pushed up to an excited-state (one at a time) but then are each brought back down to their ground-state, passing their energy to excite the next one - Inside the reaction center complex, is a molecule capable of accepting electrons (primary electron acceptor)- When this molecule gets excited, the electron does not go back down to ground-state, instead it is transferred from p680 down an electron transport chain to another primary acceptor p700.- Each photoexcited electron passes from the primary electron acceptor of photosystem 2 to photosystem 1 (photosystem 2 is before photosystem one becauseof the difference in times they were discovered and