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October, 2006
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What is Photosynthesis?

JoVE 10748

Photosynthesis is a multipart, biochemical process that occurs in plants as well as in some bacteria. It captures carbon dioxide and solar energy to produce glucose. Glucose stores chemical energy in the form of carbohydrates. The overall biochemical formula of photosynthesis is 6 CO2 + 6 H2O + Light energy → C6H12O6 + 6 O2. Photosynthesis releases oxygen into the atmosphere and is largely responsible for maintaining the Earth’s atmospheric oxygen content. Photosynthetic reactions occur in chloroplasts, specialized membrane-enclosed compartments in the plant cell. Chloroplasts consist of coin-like stacks of thylakoids. One such stack is called a granum. The thylakoid membranes are enriched with chlorophyll, a green pigment that gives plants and especially their leaves their green color. The chlorophyll molecule absorbs light energy in the form of photons from violet-blue, and orange and red wavelengths. The photons initiate a cascade that powers the reactions of Photosystem II and Photosystem I that produce ATP and NADPH. These two molecules are then used to power the light-independent reactions of the Calvin Cycle that take place in the stroma of the chloroplast to produce complex carbohydrates. Some plants, like corn and cacti that grow in dry, hot climates, use modi

 Core: Biology

Electron Carriers

JoVE 10744

Electron carriers can be thought of as electron shuttles. These compounds can easily accept electrons (i.e., be reduced) or lose them (i.e., be oxidized). They, therefore, play an essential role in energy production because cellular respiration is contingent on the flow of electrons.

Over the many stages of cellular respiration, glucose breaks down into carbon dioxide and water. Electron carriers pick up electrons lost by glucose in these reactions, temporarily store the electrons and input them into the electron transport chain. Two such electron carriers are NAD+ and FAD, which are both derived from B vitamins. The reduced forms of NAD+ and FAD, NADH and FADH2, respectively, are produced during earlier stages of cellular respiration (glycolysis, pyruvate oxidation, and the citric acid cycle). The reduced electron carriers NADH and FADH2 pass electrons into complexes I and II of the electron transport chain, respectively. In the process, they are oxidized to form NAD+ and FAD. Additional electron carriers in the electron transport chain are flavoproteins, iron-sulfur clusters, quinones, and cytochromes. With the assistance of enzymes, these electron carriers eventually transfer the electrons to oxygen molecules. The electron carriers become oxidized as they donate electrons and re

 Core: Biology

Sensory Exam

JoVE 10113

Source:Tracey A. Milligan, MD; Tamara B. Kaplan, MD; Neurology, Brigham and Women's/Massachusetts General Hospital, Boston, Massachusetts, USA

A complete sensory examination consists of testing primary sensory modalities as well as cortical sensory function. Primary sensory modalities include pain, temperature, light touch, vibration,…

 Physical Examinations III

Nuclear Magnetic Resonance (NMR) Spectroscopy

JoVE 5680

Source: Laboratory of Dr. Henrik Sundén – Chalmers University of Technology

Nuclear magnetic resonance (NMR) spectroscopy is a vital analysis technique for organic chemists. With the help of NMR, the work in the organic lab has been facilitated tremendously. Not only can it provide information about the structure…

 Organic Chemistry

Passaging Cells

JoVE 5052

Cell lines are frequently used in biomedical experiments, as they allow rapid culture and expansion of cell types for experimental analysis. Cell lines are cultured under similar conditions when compared to freshly-isolated, or primary, cells, but with some basic important differences: (i) cell lines require their own specific growth factor cocktails and (ii) their growth must be more closely…

 Basic Methods in Cellular and Molecular Biology

Palladium-Catalyzed Cross Coupling

JoVE 10353

Source: Vy M. Dong and Faben Cruz, Department of Chemistry, University of California, Irvine, CA

This experiment will demonstrate the concept of a palladium-catalyzed cross coupling. The set-up of a typical Pd-catalyzed cross coupling reaction will be illustrated. Pd-catalyzed cross coupling reactions have had a profound effect on how…

 Organic Chemistry II

Mössbauer Spectroscopy

JoVE 10448

Source: Joshua Wofford, Tamara M. Powers, Department of Chemistry, Texas A&M University 

Mössbauer spectroscopy is a bulk characterization technique that examines the nuclear excitation of an atom by gamma rays in the solid state. The resulting Mössbauer spectrum provides information about the oxidation state, spin…

 Inorganic Chemistry

Near-infrared Fluorescence Imaging of Abdominal Aortic Aneurysms

JoVE 10394

Source: Arvin H. Soepriatna1, Kelsey A. Bullens2, and Craig J. Goergen1

1 Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana

2 Department of Biochemistry, Purdue University, West Lafayette, Indiana

Near-infrared fluorescence (NIRF) imaging…

 Biomedical Engineering

Coordination Chemistry Complexes

JoVE 10179

Source: Laboratory of Dr. Neal Abrams — SUNY College of Environmental Science and Forestry

Transition metals are found everywhere from vitamin supplements to electroplating baths. Transition metals also make up the pigments in many paints and compose all minerals. Typically, transition metals are found in the cationic form since they …

 General Chemistry
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