08-Cell_metabolism - BSCI330 Cell biology and physiology...

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BSCI330 – Cell biology and physiology Fall 2009 LAB MANUAL – Lab Exercise #8 Carpenter et al. 2009. BSCI330 Laboratory Manual. University of Maryland, College Park. 1 EXERCISE 8: CELLULAR METABOLISM Enzymes play critical roles in promoting and controlling the various chemical reactions that occur in cells. Cumulatively, all of these chemical reactions are referred to as metabolism , and it is through the many interrelated metabolic pathways that a cell channels and manipulates a continuous flow of energy to carry out the work needed to sustain life. The scientific discipline of biochemistry is essentially the study of how these metabolic pathways function and interact with each other. We will be examining various aspects of cellular metabolism over a two-week period. During the first week you will complete two experiments related to anabolic metabolism (synthesis). On the second week you will do one experiment related to catabolic metabolism (disassembly). Don’t forget to think and write predictions for ALL experiments in your lab notebook before class. Week 1: Anabolic Metabolism Experiment 1—Photosynthesis: The Hill Reaction Photosynthesis is the fundamental reaction in which radiant light energy is absorbed by the chloroplast pigment chlorophyll and converted into chemical energy in the molecular form of ATP and NADPH. This chemical energy is then used to drive the Calvin cycle in the production of three-carbon sugars, which are subsequently converted to various types of carbohydrates. We will discuss the production of carbohydrates in Experiment 2. Light + CO 2 + 2H 2 O n (CH 2 O) + H 2 O + O 2 Directly or indirectly, the living world derives its carbon, hydrogen, oxygen and energy from the photosynthetic activity of autotrophs such as green plants. Carbon and hydrogen are fixed into the carbohydrate products of photosynthesis, while oxygen is released as a secondary product. The fixed carbon and hydrogen are eventually used as fuel by heterotrophs such as ourselves. This fuel is burned or oxidized with available oxygen, yielding carbon dioxide and water and thus completing the biological cycle. It is impossible to imagine how cellular life could exist on earth without the continuing action of photosynthesis to channel new energy into the biosphere. Photosynthesis takes place in specialized organelles called chloroplasts , which are bound by a double-membrane envelope. The outer membrane is permeable to many kinds of macromolecules due to the presence of porins. The inner membrane is much less permeable and contains specialized molecular transporters. Within the chloroplast is a third system of membranous structures, a series of flattened sacs called thylakoids . The inner compartment or lumen of the thylakoid system is physically separate from the rest of the chloroplast interior or stroma . Thylakoid membranes are often arranged in stacks called grana , interconnected by extensions referred to as stroma thylakoids. Most of the photosynthetic machinery,
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This note was uploaded on 12/15/2009 for the course BSCI 330 taught by Professor Payne during the Spring '08 term at Maryland.

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08-Cell_metabolism - BSCI330 Cell biology and physiology...

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