Question: You buy a sample of glucose that has the radioactive carbon-14 (14C) isotope at the second position (Carbon #2). All other carbon positions in the glucose molecule has the 12C isotope. 14C is only a label and does not alter the biochemical behavior of the molecules in which it is found. This glucose sample is mixed with all the enzymes derived from muscle cells, which initially contain no other 14C-labeled chemicals. A) Draw the Haworth structure of glucose and indicate which carbon is Carbon #2 using a different color. B) In order, draw every metabolic step involved in converting the 14C-labeled glucose molecule into 14C-labeled Pyruvate. See general instructions below. C) Convert 14C-labeled Pyruvate into 14C-labeled Acetyl-CoA. Show the product of each of the three steps catalyzed by pyruvate dehydrogenase complex. See general instructions below. D) Assume all the 14C-labeled Acetyl-CoA formed enters the citric acid cycle at the same time. Draw the citric acid cycle intermediates up to and including malate, and indicate the position of the 14C-label in each intermediate. See general instructions below. E) Continue to draw citric acid cycle intermediates up until a 14C-labeled CO2 molecule is generated by the cycle. How many turns of the citric acid cycle must be made before 14CO2 is released? Which enzymatic reaction in the citric acid cycle could first catalyze the release of 14CO2? See general instructions below. F) Can 14CO2 be released at a different step in the citric acid cycle? Explain your answer. General Instructions for sections B, C, D and E: Draw the chemical structure of the final molecule(s) that is formed by each enzyme in the catabolic pathways and includes the 14C-label. Intermediates such as cis-aconitate do not need to be included. To follow the 14C-atom through the pathways: i) Track the 14C-labeled carbon atom in every molecule by showing it in a different color ii) Include all carbon (C), oxygen (O) and hydrogen (H) atoms in all chemical structures. iii) Provide the names of the enzyme and coenzymes (if applicable) that are involved in the catalysis of each reaction. iv) Provide the name of each molecule produced by the process v) Indicate if the reaction is reversible or not using arrows.

Environmental science studies the interactions between the physical, chemical, and biological components of the environment, including their effects on all types of organisms. earth science (also known as geoscience), is an inclusive term for all sciences related to earth (geology, meteorology, oceanogr maphy, etc).  although environmental and earth science cover essentially the same material, environmental science places greater emphasis on the biological realm, while earth science places greater emphasis on the physical realm.    environmental and earth science study the interactions of four major systems or “spheres” (figure 8.6).  the  geosphere  consists of the core, mantle and crust of the earth.the  atmosphere  contains all of the earth’s air and is divided into troposphere, stratosphere, mesosphere, thermosphere and ionosphere.the  hydrosphere  contains all of the solid, liquid and gaseous water on earth, extending from the depths of the sea to the upper reaches of the troposphere where water is found.  ninety-seven percent of the hydrosphere is found in salty oceans, and the remainder is found as vapor or droplets in the atmosphere and as liquid in ground water, lakes, rivers, glaciers and snowfields.  the  biosphere  is the collection of all earth’s life forms, distributed in major life zones known as biomes:   tundra, boreal forest, temperate deciduous forest, temperate grassland, desert, savannah, tropical rainforest, chaparral, freshwater, and marine.although the four systems have their unique identities, there is substantial interaction between them.  environmental scientists study the effects of events in one sphere on the other spheres. for example, a volcanic eruption in the geosphere may cause profound direct and indirect effects on the hydrosphere, atmosphere and biosphere as follows: example 1 (volcano)    on may 18, 1980, mount saint helens, in the state of washington, erupted.  this event altered the surrounding environment, and provided scientists with an opportunity to study the effects of volcanic eruptions on the geosphere, hydrosphere, atmosphere and biosphere.  such studies are vital because volcanic eruptions will continue to occur, and will have increasing impact on humans as people continue to settle lands closer to dormant volcanoes. the following are but a few of the myriad of interactions resulting from a volcanic 

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