BIOL 1543 Custom Edition Lecture 2 Outline of Last Lecture I Energy is the capacity to perform work II Laws of Thermodynamics III Heat loss during energy transformation IV Chemical reactions either store or release energy V Cellular chemical reactions VI Amazing ATP VII Enzymes VIII Specific enzymes catalyze each cellular reaction IX Membranes X Membrane phospholipids form a bilayer XI Cell Membranes XII Passive tranport XIII Facilitated transport XIV Cells expend energy for active transport XV Exocytosis and endocytosis XVI Cellular respiration XVII Breathing XVIII Cellular respiration banks energy in ATP molecules XIX Stages of Cellular respiration XX Electron transport These 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 XXI Overview Outline of Current Lecture I Photosynthesis II Life s energy cycle III Photosynthesis IV Life s energy producers V Photosynthesis occurs in chloroplast VI Plants produce O2 gas by splitting water VII Photosynthesis occurs in two stages VIII THE LIGHT REACTIONS CONVERTING SOLAR ENERGY TO CHEMICAL ENERGY IX Photosystems capture solar power X The light reactions XI The Calvin Cycle Converting Co to Sugars 2 XII Photosynthesis Reviewed XIII Fermentation XIV Fermentation in muscle cells XV Interconnections between molecular breakdown and synthesis Current Lecture I Photosynthesis a The fuel for respiration ultimately comes from photosynthesis i All organisms can harvest energy from organic molecules ii Plants can make these molecules from inorganic sources by the process of photosynthesis II Life s energy cycle a Photosynthesis and cellular respiration provide energy for life i Cellular respiration makes ATP and consumes O2 during the conversion of glucose to CO2 and H2O ii Photosynthesis uses solar energy to produce glucose and O2 from CO2 and H2O III Photosynthesis a Photosynthesis is the process by which certain organisms use light energy to make sugar and oxygen gas from carbon dioxide and water IV Life s energy producers a Autotrophs are the producers of the biosphere i Autotrophs produce their own food and sustain themselves without eating other organisms ii Plants algae and some bacteria are photoautotrophs iii Photoautotrophs produce food consumed by virtually all organisms iv Chemoautotrophs are the other form of autotroph and are limited in number V Photosynthesis occurs in chloroplasts a In plants photosynthesis occurs primarily in chloroplasts in the leaves The chloroplasts contain stroma and stacks of thylakoids called grana b the stoma is a hole that allows for gas exchange c the fluid inside the chloroplast is stroma not to get confused with stoma VI Plants produce O2 gas by splitting water a The O produced by photosynthesis is made from the oxygen atoms in 2 water VII Photosynthesis occurs in two stages a The complete process of photosynthesis consists of two linked sets of reactions the light reactions and the Calvin cycle b The light reactions stage 1 in thylakoids convert light energy to chemical energy producing O and high energy electrons occurs in the 2 thylakoids c The Calvin cycle Stage 2 AKA the dark stage in the stroma assembles sugar molecules from CO using ATP and the high energy electrons from 2 the light reactions G3P builds sugar and is the output in this reaction stage VIII THE LIGHT REACTIONS CONVERTING SOLAR ENERGY TO CHEMICAL ENERGY a Visible radiation drives the light reactions i Certain wavelengths of visible light absorbed by pigments drive the light reactions of photosynthesis IX Photosystems capture solar power a Thylakoid membranes contain multiple photosystems that absorb light energy which excites electrons b Each photosystem consists of i Light harvesting complexes of pigments around the edge ii A reaction center that receives excited electrons from chlorophyll X The light reactions a In the light reactions electron transport chains generate ATP and highenergy electrons i Electron transport from photosystem II to I provides energy to make ATP ii Photosystem I creates high energy electrons iii Photosystem II splits water releasing O2 b Chemiosmosis powers ATP synthesis in the light reactions i The electron transport chain pumps H into the thylakoid space ii The diffusion of H back across the membrane through ATP synthase produces ATP XI The Calvin Cycle Converting Co to Sugars 2 a ATP powers sugar synthesis in the Calvin cycle b Light is not required c The Calvin cycle i Occurs in the chloroplast s stroma ii Using carbon from CO2 electrons from NADPH and energy from ATP the cycle constructs G3P which is used to build glucose and other organic molecules like starch and cellulose 1 CO2 and ATP in and G3P out XII Photosynthesis Reviewed a Photosynthesis uses light energy to make food molecules XIII Fermentation a Fermentation is an anaerobic alternative to cellular respiration b Under anaerobic conditions many kinds of cells can use glycolysis alone to produce small amounts of ATP i In lactic acid fermentation type 1 NADH is oxidized to NAD as pyruvate is reduced to lactate in humans 2 2 NADH NAD 2 NADH 2 NAD GLYCOLYSIS 2 ADP 2 P 2 ATP Glucose 2 Pyruvate 2 Lactate ii In alcohol fermentation type 2 NADH is oxidized to NAD while converting pyruvate to CO and ethanol produce beer and bread 2 this way XIV Fermentation in muscle cells a lactic acid fermentation present in worked muscles gives a burst of energy for a short time i feeling the burn you are running out of oxygen and your body switches over to the lactic acid fermentation to exceed the normal biological amount of oxygen ii Micro trauma at a cellular level causes sore muscles after exercising XV Interconnections between molecular breakdown and synthesis a Cells use many kinds of organic molecules as fuel for cellular respiration b Carbohydrates fats and proteins can all fuel cellular respiration when they are converted to molecules that enter glycolysis or the citric acid cycle c Lactic acid fermentation will give us a burst of energy for a short amount of time Food such as peanuts Carbohydrates Sugars Fats Proteins Glycerol Fatty acids Amino acids Amino groups Pyruvate Glucose G3P GLYCOLYSIS Acetyl ATP CITRIC ACID CYCLE OXIDATIVE PHOSPHORYLATION Electron Transport and Chemiosmosis d Food molecules provide raw materials for biosynthesis i Cells use some food molecules and intermediates from glycolysis and the citric acid cycle as raw materials burned for