5Aerobic Respiration aerobic = with oxygen C6H12O6 + O > CO2 + H2O + ATPThree process occur in aerobic respiration1. Glycolysisglucose2 pyruvic acidPEPCCCoccurs in the cytoplasmoxygen is not requiredelectron acceptor is nicotinamide adenine dinucleotideNAD --> NADH
9Aerobic Respiration cont’d 3. Electron transportelectrons transferred from NADH, FADH2 to oxygen and water is formedoxidative phosphorylationATP synthase complexprotons pumped across membraneoccurs in mitochondriaconversion equivalents:NADH = 3 ATPFADH2 = 2 ATP
11Aerobic Respiration cont’d Energy from aerobic respirationGlycolysisnet gain of 6 ATPpyruvic acid --> acetyl-CoA2 NADH = 6 ATPKrebs Cycle2 ATPElectron Transport6 NADH = 18 ATP2 FADH2 = 4 ATPoxidative phosphorylationTotal = 36 ATP / glucose39% of energy available61% of energy is lost as heat
12Anaerobic Respiration (without oxygen)1. ethanol fermentationglucose ---> pyruvic acid ---> ethyl alcohol + CO2 + ATPC6H12O > 2C2H5OH + 2CO ATP25% of energy of aerobic respirationoccurs in some plants and microorganisms including yeasts
13Alcohol FermentationAncient Eqyptian wall painting: historical record of wine-making~ 5000 yrs ago, perhaps earlierGrapes were picked, crushed by foot, juice collected in jugs, then fermented producing wine.
14Anaerobic Respiration cont’d 2. lactic acid fermentationglucose ---> pyruvic acid ---> lactic acid + ATPC6H12O > 2C3H6O ATP22% of energy of aerobic respirationmammalian muscle and some microorganisms
23What is the connection between respiration and photosynthesis?
24A review: Carbon flow: from atmosphere through photosynthesis in autotrophsthrough cellular respiration in autotrophs and heterotrophsback into atmosphere
25Carbon CycleCarbon atom movement. Numbers are estimates of carbon expressed in billions of metric tons stored in reservoirs (2000 data)CARBON + OXYGEN -> CO2 + heatCarbon released by respiration and combustion now exceeds the amount fixed by photosynthesis, by 3 billion metric tons/year.
27Production of CO2 fossil fuels produces 70% of CO2 emmisions U.S. 24%EU 15%China 15%Russia 6%India 5%Japan 5%per capita CO2 emmissions (tons/capita)U.S. 5.4EU 2.6China 0.8Russia 2.9India 0.3Japan 2.5
30Global Response to global warming Kyoto Protocolprotocol to the international Framework Convention on Climate Change with the objective of reducing Greenhouse gases that cause climate changeagreed on 11 December 1997 at the 3rd Conference of the Parties to the treaty when they met in Kyoto, and entered into force on 16 February 2005.Participation in the Kyoto Protocol, as of December 2011,Brown = Countries that have signed and ratified the treaty (Annex I & II countries in dark brown)Blue = No intention to ratify at this stageDark blue = Canada, which withdrew from the Protocol in December 2011 Grey = no position taken or position unknownUnited States although a signatory to the Kyoto Protocol, has neither ratified nor withdrawn from the Protocolboth Clinton and Bush administrations have refused obtain senate ratificationreasons:top emitters excluded (China, India)cause U.S. economic strain to meet requirements
31Correlation Between Historic CO2 Levels and Historic Temperatures: Ice core data Most important, we can look at isotopes of oxygen. In cold years, water molecules with slightly-lighter oxygen atoms evaporate more easily than water slightly-heavier isotopes. Consequently, by looking at the proportions ofheavier and lighter oxygen atoms (isotopes), climatologists can reconstruct temperatures over time, and map temperature changes against CO2 concentrations and other atmospheric components.The first very long The longest ice record was from the ever collected is the Vostok ice core , which reached3,100 m into the Antarctic ice, and gives us a record of both global temperatures and atmospheric CO2 over the past 420,000 years (fig. 9.8). A team of Russian scientists worked for 37 years at the Vostok a site, about 1,000 km from the South Pole to extract this ice core. A similar core , nearly as long as the Vostok, has been drilled from the Greenland ice sheet. More recently the European Project for Ice Coring in Antarctica (EPICA) has produced a record reaching back over 800,000 years.Other glaciers throughout the world have also now been cored. All these cores show that climate has varieddramatically over time, but that there is a close correlation between atmospheric temperatures and CO2 concentrations.3131
32http://cdiac.esd.ornl.gov/ Carbon Dioxide Information Analysis Center Air samples at Mauna Loa, Hawaii are collected continuously from air intakes at the top of four 7-m towers and one 27-m tower. Four air samples are collected each hour for the purpose of determining the CO2 concentrationCarbon Dioxide Information Analysis Center
35What Causes Natural Climatic Swings? Modest climate changes correspond to an 11-year cycle in the Sun’s intensityMilankovitch Cycles are caused by changes in the Earth’s orbit (100,000 yr), rotation (40,000 yr) and the wobble of its axis (26,000 yr)Ice core records also show that there have been repeated climate changes over time. What causes these periodic (repeated) changes? Modest changes correspond to an 11-year cycle in the sun's intensity. About every 11 years there is a peak in incoming solar energy. More dramatic changes are associated with periodic shifts in the earth’s orbit and tilt (fig. 9.9). These are known as the Milankovitch cycles, after the Serbian scientist Milutin Milankovitch, who first described them in the 1920s. There are three of these cycles: (1) The earth’s elliptical orbit stretches and shortens in a 100,000- year cycle. (2) , while the earth's axis of rotation changes its angle of tilt in a 40,000- year cycle. (3) Furthermore, over a 26,000-year period, the axis wobbles like an out- of-balance spinning top.9-3535
36temperature/precipitation changes from the 20th Century The impacts of global change are not likely to be distributed evenly throughout the world. For instance, the following graph of the world shows that estimates of temperature and precipitation changes very in different parts of the world.
37Possible Implications of and Debate Surrounding Global Warming More heat wavesMore extreme storm activityChanges in rainfall, snowfall patternsEcosystem effectsHigher sea levelsMore diseaseWinners: Siberia, ScandinaviaLosers: most of U.S. (particularly SE; Washington may be nicer), island statesThe potential impacts of global warming are numerous, and it is difficult to discount much of anything important. Depending on the location and current weather conditions, future climates could be hotter or cooler, show more or less precipitation, show more extreme storm activity, flooding of coastal areas, and potentially result in the increased spread and incidence of disease. One of the major impacts of climate change could be the migration or extinction of species not adapted to the future climate. In particular, where mountains range from east vs. west instead of north vs. south, extinctions are likely since the species dependent on previous conditions could not move north or south to adjust their environments.
39Consequences of Global Warming uncertaintywhy?testing the predictionsProbable environmental alterations from GW:changing climate and weather patternsintensity of weather increasedrising sea levels - 3’ higher all around the world in 100 yearsshifting climate zones causing ecosystem devastation and species losses
40Consequences of CO2 increase CO2 as a Greenhouse Gasthird most abundant gas in atmosphereabsorbs heat energy reflected by earthacts as a blanket around earthproduces the greenhouse effectThis is normal, and good!Excessive greenhouse gas accumulation?increase GH gas; increase heat absorptionincreased heat of earthGlobal Warming
41CO2 in atmosphere key component of nature’s thermostat If carbon cycle removes too much CO2If carbon cycle generates too much CO2earth coolsearth warms