Chapter 10 Photosynthesis Photosynthesis plants algae cyano bacteria sulfur bacteria and protists are capable of this process evolved in the cyano bacteria Photoautotroph photo light energy is used to make ATP auto organic compounds like carbohydrates are made from inorganic compounds sometimes called producers they produce all the organic molecules that are used by the other organisms that cant go through photosynthesis Chemoheterotroph chemo chemical energy is used to make ATP hetero organic compounds are obtained from others commonly called consumersconsume the organic molecules 6CO2 12H2O light C6H12O6 06 6H20 CO2 2H20 CH20 02 H20 simplified cellular respiration in reverse o o o o Endergonic reaction energy in from light Leaf Anatomy Upper epidermis Lower epidermis Stoma hole in the leaf usually on the underside of the leaf mostly in the lower epidermis allow oxygen gas out of the leaf and CO2 to go into the leaf o Cuticle made of wax purpose is to prevent transpiration the evaporation of water from a plant they would quickly wilt o Mesophyll central region of the cell 1 Upper layer gives most of the sunlight composed of tightly packed vertical cells called the palisade mesophyll 2 Under the palisade mesophyll is the spongy mesophyll gets less sunlight o Veins 1 Xylem cells xylem sap water and minerals type of cells that carry xylem sap up the cells 2 Phloem cells smaller on the lower side of the vein conduct phloem sap rich in sucrose cells of the root of the cells need sugar for energy cells ex phloem sap moves to the roots Van Niel Standford 1930s studied sulfur bacteria capable of photosynthesis called this because they use hydrogen sulfide 2H2S in photosynthesis instead of water when they undergo photosynthesis you can see specs of yellow which is sulfur Radioisotopes radioactive oxygen called Oxygen 18 To find out where oxygen comes from in photosynthesis experiments were done using radioactive isotopes C02 2H20 CH2O O2 H20 o Example of a redox reaction involves both an oxidation loss of electrons or hydrogen and a reduction addition of electrons or hydrogen o In photosynthesis water is oxidized and carbon dioxide is reduced o Cellular respiration exergonic photosynthesis endergonic Photosynthesis o 2 sub reactions 1 Light dependent reaction this depends on sunlight energy to proceed H20 02 o Combine ADP and a phosphate to make ATP this process is done through chemiosmosis in the thylakoid o Water is oxidized the two hydrogens left over are given to a hydrogen truck NADP which is reduced by taking in the hydrogen and you get NADHPH H 2 Light independent reaction Calvin cycle does not require light uses the products of the light dependent reaction CO2 CH2O o ATP is consumed the reduced NADPH H is oxidized the CO2 is reduced to make the carbohydrate CH20 Name the two products produced in the light dependent reaction that are consumed or used in the light independent reaction NADPH H and ATP o Plants do have mitochondria for cellular respiration Light in photosynthesis part of the electromagnetic spectrum o Composed of photons have particle and wave like properties crest to crest or trough to through is one wave link o The energy of a photon is inversely proportion to the wave linkEx wave link goes down shorter energy goes up Pigments o As light meets matter light can be 1 Reflected 2 Transmitted 3 Absorbed o Pigment is any substance that absorbs visible light Blue pigment reflects or transmits blue wavelengths All of the other visible wavelengths of light are absorbed Color you see absorbs everything except what you see o Spectrophotometer spectro spectrum of visible light photo light meter measure measures the spectrum of light Engalmann 1883 aerobic bacteria swim to the most oxygen they swim to the purples and blues reds and oranges rather than green Chlorophyll A CH3 in porphynn nng Chlorophyll B CHO in porphytin nng o Accessory pigments allow the plant to absorb lights that aren t green Ranthophylls yellow Carotenoid orange Deciduous trees during fall the trees look yellow orange because the chlorophyll has been broken down to allow for green leaves in spring Pigment molecules have a porphynn suurounds a metal ion ring Cytochromes chlorophyll and hemoglobin Has a hydrocarbon tail that attaches to a thylakoid Action spectrum of photosynthesis measures the release of oxygen Photo excitation of chlorophyll uses fluorescence o Black light is a form of uv light o When the photon goes to the pigment it excites the pigment the energy goes up to a higher electron shell then falls back down to the original orbital and releases energy and a pigment we can see with our own eyes a photon with a longer wavelength second law of thermodynamics Light dependent reaction of photosynthesis o Plants absorb light through a photosystem o Light harvesting complex composed of 300 pigments and proteins o Reaction center 2 chlorophyll molecules and a primary electron accepter o Photosystem found in thrlakoid membranes Photosystem II P680 the wavelength of photon that the system will absorb Photosystem I P700 Makes NADH H and ATP Linear noncyclic electron flow 2 reactions Picture diagram o NADP reduced once all reduced goes to cyclic electron flow o Electrons flow downhill releasing energy for the synthesis of ATP for chemiosmosis Cyclic electron flow o The light independent reaction Calvin Cycle o Uses more ATP than NADPH H o The electron goes through the first ETS Chemiosmosis creation of a trans membrane proton gradient the gradient is a source of potential energy for cellular work not always for ATP synthesis o Seen in plants animals and bacteria can be used in plants for secondary active transport o Review notes from last exam Chemiosmosis in the thylakoid the protons are pumped from the stroma space between grana into the thylakoids of the grana high concentration of protons in the thylakoid space once the trans membrane proton gradientthey can then flow downhill and create ATP o Granum stack of thylakoids o Photosystem along the thylakoid o PH in thylakoid space 5 o PH in stroma 8 o Some of the protons in the thylakoid space come from the photolysis of water occurs in the thylakoid space bonus o ATP and NADP products are released into the stroma for the calvin cycle Calvin Cycle light independent reaction o Uses ATP and reduced NADP to make a carbohydrate the whole point of photosynthesis o About half of glycolysis in reverse o Sub reaction o Occurs in the stroma of the chloroplast o