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Sodium Chloride: A ubiquitous sodium salt that is commonly used to season food. It plays an important biological role in maintaining the osmotic tension of blood and tissues. The Osmolar concentration this and other Salts accounts for Salinity which influences the types of organisms that live in an Environment.

Transformation of E. coli Cells Using an Adapted Calcium Chloride Procedure

JoVE 10515

Source: Natalia Martin1, Andrew J. Van Alst1, Rhiannon M. LeVeque1, and Victor J. DiRita1
1 Department of Microbiology and Molecular Genetics, Michigan State University

Bacteria have the ability to exchange genetic material (DeoxyriboNucleic Acid, DNA) in a process known as horizontal gene transfer. Incorporating exogenous DNA…



JoVE 10670

A solvent is a substance, most often a liquid, that can dissolve other substances. Here, the substance being dissolved is called a solute. When a solvent and a solute combine, they form a solution that, at the molecular level, is a homogenous mixture of both the solvent and the solute. Water is a universal biological solvent. Its polar structure allows it to dissolve many other polar compounds. The ability of water to dissolve is governed by a balance between water molecules binding to each other and binding to the solute. A saturated solution contains the maximum amount of dissolvable solute. For example, salt (NaCl) is readily dissolved in water to create salt water, or saline. It dissolves because salt dissociates into its respective ions sodium (Na+) and chloride (Cl-). Water is polar, so its oxygen atom, being slightly negative, is attracted to the positive sodium ions. Several water molecules can bind to a single sodium ion, creating a sphere of hydration. Likewise, water’s hydrogen atoms are slightly positive and are attracted to the negative chloride ions, again creating a sphere of hydration around the chloride ions. These hydration shells keep the solute particles separated and dispersed, creating a solution. A saturated solution of salt water (at room temperature) contains about 26% sodium chloride. If more sa

 Core: Chemistry of Life

Protein Crystallization

JoVE 5689

Protein crystallization, obtaining a solid lattice of biomolecules, elucidates protein structure and enables the study of protein function. Crystallization involves drying purified protein under a combination of many factors, including pH, temperature, ionic strength, and protein concentration. Once crystals are obtained, the protein structure can be elucidated by x-ray diffraction and…


DNA Isolation and Restriction Enzyme Analysis- Concept

JoVE 10628

The revelation of DNA as the hereditary molecule in all organisms has led to enormous scientific and medical breakthroughs and significantly enhanced our understanding of ourselves and other organisms. DNA isolation and profiling have been the fundamental first steps for many of the advancements in the past century; from identification of gene function, to revolutions of agriculture and…

 Lab Bio

Diffusion and Osmosis - Prep Student

JoVE 10563

Preparation of Solutions for the Agar Cube Experiment
IMPORTANT: Wear gloves, goggles, and appropriate personal protective equipment – chemicals can be hazardous at high concentrations.
For the diffusion indicator solution, weigh out 1 g of phenolphthalein and add it to a beaker containing 100 mL of 95% ethanol.
To make the basic…

 Lab Bio

Nucleophilic Substitution

JoVE 10465

Source: Vy M. Dong and Daniel Kim, Department of Chemistry, University of California, Irvine, CA

Nucleophilic substitution reactions are among the most fundamental topics covered in organic chemistry. A nucleophilic substitution reaction is one where a nucleophile (electron-rich Lewis base) replaces a leaving group from a carbon…

 Organic Chemistry II

Community DNA Extraction from Bacterial Colonies

JoVE 10218

Source: Laboratories of Dr. Ian Pepper and Dr. Charles Gerba - Arizona University
Demonstrating Author: Luisa Ikner

Traditional methods of analysis for microbial communities within soils have usually involved either cultural assays utilizing dilution and plating methodology on selective and differential media or direct count assays.…

 Environmental Microbiology

Determining the Mass Percent Composition in an Aqueous Solution

JoVE 10172

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

Determining the composition of a solution is an important analytical and forensic technique. When solutions are made with water, they are referred to as being aqueous, or containing water. The primary component of a solution is referred to as…

 General Chemistry

Separation of Mixtures via Precipitation

JoVE 5558

Source: Laboratory of Dr. Ana J. García-Sáez — University of Tübingen

Most samples of interest are mixtures of many different components. Sample preparation, a key step in the analytical process, removes interferences that may affect the analysis. As such, developing separation techniques is an important endeavor not…

 Organic Chemistry

Freezing-Point Depression to Determine an Unknown Compound

JoVE 10137

Source: Laboratory of Lynne O' Connell — Boston College

When a solid compound is dissolved in a solvent, the freezing point of the resulting solution is lower than that of the pure solvent. This phenomenon is known as freezing-point depression, and the change in temperature is directly related to the molecular weight of the…

 General Chemistry

n-Butyllithium Titration

JoVE 10338

Source: Vy M. Dong and Diane Le, Department of Chemistry, University of California, Irvine, CA

This experiment will demonstrate a simple technique to titrate and obtain an accurate concentration of the organolithium reagent, n-butyllithium (n-BuLi). Organolithium reagents are extremely air- and moisture-sensitive and…

 Organic Chemistry II

Grignard Reaction

JoVE 10337

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

This experiment will demonstrate how to properly carry out a Grignard reaction. The formation of an organometallic reagent will be demonstrated by synthesizing a Grignard reagent with magnesium and an alkyl halide. To demonstrate a common use…

 Organic Chemistry II


JoVE 10352

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

This experiment will demonstrate the concept of organocatalysis by illustrating the proper setup of a reaction that utilizes enamine catalysis. Organocatalysis is a form of catalysis that uses substoichiometric amounts of small organic…

 Organic Chemistry II

Serial Dilutions and Plating: Microbial Enumeration

JoVE 10507

Source: Jonathan F. Blaize1, Elizabeth Suter1, and Christopher P. Corbo1
1 Department of Biological Sciences, Wagner College, 1 Campus Road, Staten Island NY, 10301

Quantitative assessment of prokaryotes can be onerous given their abundance, propensity for exponential proliferation, species diversity within a population, and specific …


Conversion of Fatty Acid Methyl Esters by Saponification for Uk'37 Paleothermometry

JoVE 10158

Source: Laboratory of Jeff Salacup - University of Massachusetts Amherst

The product of an organic solvent extraction, a total lipid extract (TLE), is often a complex mixture of hundreds, if not thousands, of different compounds. The researcher is often only interested in a handful of compounds or, if interested in many, may need to remove unwanted constituents that…

 Earth Science

Histotypic Tissue Culture

JoVE 5787

Although two-dimensional tissue culture has been common for some time, cells behave more realistically in a three-dimensional culture, and more closely mimics native tissue. This video introduces histotypic tissue culture, where the growth and propagation of one cell line is done in an engineered three-dimensional matrix to reach high cell density. Here, we show the…


Scanning Electron Microscopy (SEM)

JoVE 5656

Source: Laboratory of Dr. Andrew J. Steckl — University of Cincinnati

A scanning electron microscope, or SEM, is a powerful microscope that uses electrons to form an image. It allows for imaging of conductive samples at magnifications that cannot be achieved using traditional microscopes. Modern light microscopes can achieve a…

 Analytical Chemistry

Standardized Measurement of Nasal Membrane Transepithelial Potential Difference (NPD)

1Department of Medicine and the Gregory Fleming James Cystic Fibrosis Center, University of Alabama at Birmingham, 2Department of Pulmonology and Tuberculosis, University Medical Center Utrecht, 3Center for Experimental Medicine, Queens University, Northern Ireland, 4Hadassah Hebrew University Medical Center, Jerusalem, 5Centro Fibrosi Cistica, Azienda Ospedaliera Universitaria Integrata, 6Service de Pneumologie et Allergologie Pédiatriques and Center de Ressources et de Compétence de la Mucoviscidose, Hôpital Necker Enfants Malades, 7INSERM U 1151, Institut Necker Enfants Malades

JoVE 57006


Measurement of Extracellular Ion Fluxes Using the Ion-selective Self-referencing Microelectrode Technique

1Department of Dermatology, Institute for Regenerative Cures, University of California, Davis, 2Departamento de Biologia, Centro de Biologia Molecular e Ambiental, Universidade do Minho, 3Department of Neurology and Center for Neuroscience, University of California, Davis Imaging of Dementia and Aging Laboratory, 4Department of Ophthalmology, Institute for Regenerative Cures, University of California, Davis

JoVE 52782


Screening for Functional Non-coding Genetic Variants Using Electrophoretic Mobility Shift Assay (EMSA) and DNA-affinity Precipitation Assay (DAPA)

1Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital, 2Medical Scientist Training Program, University of Cincinnati, 3Immunology Graduate Program, University of Cincinnati, 4Divisions of Biomedical Informatics and Developmental Biology, Cincinnati Children's Hospital

JoVE 54093


Creating a Structurally Realistic Finite Element Geometric Model of a Cardiomyocyte to Study the Role of Cellular Architecture in Cardiomyocyte Systems Biology

1Cell Structure and Mechanobiology Group, University of Melbourne, 2Systems Biology Laboratory, Melbourne School of Engineering, University of Melbourne, 3Department of Biomedical Engineering, University of Melbourne, 4School of Mathematics and Statistics, Faculty of Science, University of Melbourne, 5Department of Engineering Science, University of Auckland, 6Advanced Microscopy Facility, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, 7ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of Melbourne, 8School of Medicine, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, 9Living Systems Institute, University of Exeter

JoVE 56817


Generation and On-Demand Initiation of Acute Ictal Activity in Rodent and Human Tissue

1Division of Fundamental Neurobiology, Krembil Research Institute, 2Institute of Medical Science, Faculty of Medicine, University of Toronto, 3Institute of Biomaterials and Biomedical Engineering, University of Toronto, 4Division of Neurosurgery, Department of Surgery, University of Toronto, 5Division of Neurology, Department of Medicine, University of Toronto, 6Department of Physiology, University of Toronto

JoVE 57952

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