EBIO 1210: Connections
EBIO 1210: Connections EBIO 1210
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This 5 page Class Notes was uploaded by Amy Campbell on Wednesday October 12, 2016. The Class Notes belongs to EBIO 1210 at University of Colorado at Boulder taught by William Adams, Scott Taylor, Derek Sweeney in Fall 2016. Since its upload, it has received 20 views. For similar materials see General Biology 1 in Biology at University of Colorado at Boulder.
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Date Created: 10/12/16
Photosynthesis and Plants- The Foundation of the Biosphere and Human Civilization Oxygen Photosynthesis is the source of O2, Without O2 multi- celled organisms (that depend on cellular respiration) would not have arisen, and life would be restricted to single-celled bacteria Ozone Layer Without O2 in the atmosphere, the ozone (O3) layer would not have formed. O3 shields against the most intense ultraviolet (UV) radiation, which contributed to allowing evolution of life into the terrestrial environment What do we get from the ﬁxation of all of that atmospheric CO2? Food! In all ecosystems, it is the primary producers that produce food (energy-rich molecules with C-H bonds), and consumers eat the food. Green plants use the energy of sunlight to convert CO2 to sugar by photosynthesis. the sugars are the source of thousands of compounds within plants, including the major components of the worlds food supply. Plants are a source of materials: the cell was provide structural support for the plant and also provide ﬁbers and building materials for humans, insects, birds, and many other organisms. Source of fuel and energy: Wood and peat from living plants. Coal, oil, and natural gas from plants/algae altered over time. Plants are a sink for CO2 The same CO2 that was ﬁxed by photosynthesis over the course of millions of years is now released over a few decades. Photosynthesis Atmospheric CO2 levels show annual winter increases and summer decreases due to changes in photosynthetic uses sunlight to activity. make sugars and O2 Aerobic Cellular Biofuels Respiration burns Renewable energy - one candidate = biofuels sugars with O2 and Biofuels: CO2 ﬁxed one year; burnt as biofuel the next year; Co2 and water, ﬁxed again the following year… ideally no net increase in extracting energy CO2 to make ATP for Production: Yeasts use alcoholic fermentation to convert cellular work. hexoses (from corn starch or sugar cane sucrose or cellulose) into ethanol for fuels Identify the role of Estimated reduction in greenhouse gas emissions if photosynthesis as petroleum furl was replaced by ethanol. a producer of food, 1. Ethanol from corn starch = -22% fuels, and materials Starch: major storage carbohydrate in corn grains or potato tubers Ethanol Generation using corn Starch Starch is easy to convert to hexoses However: Annual crop, high input of Identify the role of fertilizer (produced with fossil fuels): only photosynthesis as small portion of plant mass used a CO2 sink Huge food versus fuel conﬂict: Price of corn has more than tripled over the last decade 2. Ethanol from sucrose = -56% Sucrose: major carbohydrate in sugar cane & sugar beat; only 1 step to split sucrose into hexoses (for conversion to ethanol) Ethanol Generation using sucrose from sugarcane Sucrose is easy to convert to hexoses Seven harvests of cane before replanting is necessary Cane waste is burned for power and heat Still: food vs food conﬂict. 3. Ethanol from plant cellulose (cellulosic ethanol) = -91% Compare and Cellulosic ethanol: makes up the tightly packed Contrast sucrose, ﬁber structure of plant cell walls. Only some starch, and microbes have enzymes to break bond in cellulose as bases cellulose (cows and termites have microbial for biofuels symbionts that can) Grasses discussed as biofuel crops for “cellulosic” ethanol production are C4 plants Rapidly growing tree hybrid poplar discussed as another new biofuel crop is a C3 plant Still: Food vs fuel conﬂict for land area and water resources. 3 plant species with promise for cellulosic ethanol C3 vs C4 plants production: -switchgrass (C4) When leaf pores (stomates) open to allow CO2 to move in, a -Hybrid popular lot of H2O is lost at the same time. (C3) C3 plants open their pores more widely -miscanthus lose 400-500g H2O per g CO2 ﬁxed. giganteus (C4) C4 plants do not open their pores as widely lose 250-300 g H2O per g CO2 ﬁxed. C4 pathway (example: sugarcane): C4 plants possess an additional enzyme in their outer cells that ﬁxes CO2 very eﬃciently under low internal CO2 concentrations But C4 plants use two CO2 -ﬁxing cycles that both use ATP energy. They re-release the CO2 and the Relate the Calvin Cycle re-ﬁxes CO2 eﬃciently. diﬀerences Advantages of C4 plants: between C3 and ﬁx CO2 with leaf pores (stomates) less widely open C4 plants to their and need less water ecological Advances in dry, sunny climates advantages and Advantages of C3 plants: disadvantages. C3 plants need less energy since they run only one, not two cycles Advantage in less sunny, but moister climates Biofuels from Fats Identify fat as the basis for biodiesel. Problem with biodiesel directly from oil crops: The Environment Controls our Genes Devastation of tropical forests; Food food vs fuel Sugar & some starches: activate genes that promote fat Storage Slowly-digested carbohydrates: activate genes that promote fat burning Glycemic index (GI) = rapidity of conversion to glucose High GI: Chronic elevated blood glucose Sugar or rapidly digested amylopectin... regular soft drinks, candy, white bread, white rice, baking potatoes, pancakes (white ﬂour), bagel (white ﬂour) Low GI: Balanced blood glucose level Slowly digested amylose and cellulose Vegetables, whole fruit, multi-grain/whole grain bread, whole grains, sweet potatoes, spices Glycemic load (GL) = GI x amount of food consumed Diets with high GL can lead to chronic high blood glucose level and result in insulin insensitivity + lifestyle-related type 2 diabetes Chronic high blood glucose level (and even more so fructose) also elevates risk for pro-inﬂammatory diseases Proteins in blood become glycated; looks like sugar coat of bacteria; this turns on inﬂammation Sugar attachment (glycation) as basis for recognition by immune cells Membrane glucolipids and glycoproteins Relate the function in normal cell-to-cell recognition concepts of (ABO blood type) as well as in many glycemic index of diseases involving overstimulation of the diﬀerent immune response. carbohydrates and High GL diet: chronic high blood glucose glycemic load to High GL & saturates fat: visceral obesity human health High omega-6: omega-3 fat ratio is oﬀ Cholesterol and Cardiovascular Disease Inﬂammation & plaque result from white blood cell recruitment, which is triggered by the presence of glycated, oxidized LDL High LDL: result of high saturated fat intake Glycation: result of chronic high blood sugar Oxidation: result of low fruit/vegetable (antioxidant) intake Yin and Yang of Inﬂammation Good inﬂammation: from injury/infection… inﬂammation involves “calling” white blood cells to engulf and destroy injured body cells and invaders Bad inﬂammation: Overstimulation of inﬂammation causes white blood cells to attack uninjured body cells Low/no belly fat: low investment in defense, weak immune system response Moderate belly fat: adequate investment in defense, strong immune response excessive belly fat: excessive investment in defense, overstimulates immune response More problems with High Fructose Corn Syrup another part of blood sugar control is the signaling of satiety fructose does NOT enhance production of hormones that signal satiety
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