Concentration Gradient
Concentration Gradient - Related Videos
09:28
A Microfluidic Device for Quantifying Bacterial Chemotaxis in Stable Concentration Gradients
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Cited by 7 •
2010
This protocol describes the development of a microfluidic device for investigating bacterial chemotaxis in stable concentration gradients of chemoeffectors.
10:19
A CO2 Concentration Gradient Facility for Testing CO2 Enrichment and Soil Effects on Grassland Ecosystem Function
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Cited by 2 •
2015
The Lysimeter Carbon Dioxide Gradient Facility creates a 250 to 500 µl L-1 linear carbon dioxide gradient in temperature-controlled chambers housing grassland plant communities on clay, silty clay, and sandy soil monoliths. The facility is used to determine how past and future carbon dioxide levels affect grassland carbon cycling.
02:41
Concentration Cells
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2020
A concentration cell is a type of a voltaic cell constructed by connecting two almost identical half-cells, both based on the same half-reaction and using the same electrode, differing only in the concentration of one redox species. A concentration cell's potential, therefore, is determined only by the concentration difference of the particular redox species. Consider the following voltaic cell: From the given information, the cell potential of this concentration cell can be calculated using...
08:42
Density Gradient Ultracentrifugation
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2023
Density gradient ultracentrifugation is a common technique used to isolate and purify biomolecules and cell structures. This technique exploits the fact that, in suspension, particles that are more dense than the solvent will sediment, while those that are less dense will float. A high-speed ultracentrifuge is used to accelerate this process in order to separate biomolecules within a density gradient, which can be established by layering liquids of decreasing density in a centrifuge tube. The...
03:05
Gradient Centrifugation Based Purification of Nuclei: A Technique to Obtain Ultrapure Fraction of Intact Nuclei Using Density Gradient Centrifugation
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2023
In this video, we describe a simple and efficient protocol using gradient centrifugation to isolate single nuclei. Once isolated, these nuclei can be used for sequencing and genome analysis.
FAQs
Membrane selectivity determines which substances can respond directly to a gradient. A selectively permeable membrane may allow certain molecules or ions to cross while restricting others, so movement and exchange depend on both the concentration difference and membrane properties. This selectivity helps cells regulate internal composition rather than allowing all substances to equilibrate freely.
Energy-dependent transport allows cells to move substances against their natural tendency to diffuse from higher to lower concentration. Maintaining these differences preserves controlled ion and nutrient distributions across membranes. The stored gradient can then support essential functions, including regulation of cell conditions, waste removal, nerve signaling, and cellular energy production.
A concentration gradient can involve many substances, including ions, nutrients, and waste products, whereas an osmotic gradient specifically concerns differences that influence water movement across a selectively permeable membrane. This distinction matters because water balance depends on membrane permeability and the distribution of dissolved substances, while solute movement may occur through other transport processes.
Diffusion tends to reduce the difference between regions as molecules move down their concentration gradient. As the difference becomes smaller, the net movement and resulting chemical exchange generally decrease. Cells can counter this change by using energy-dependent transport, which reestablishes or maintains gradients needed for stable internal conditions and ongoing biological functions.
Differences in dissolved-substance concentration across a selectively permeable membrane can drive osmosis, the movement of water. The direction and extent of water movement depend on which substances are present and whether the membrane permits their passage. These relationships help explain how cells regulate water balance and avoid uncontrolled changes in their internal environment.
Gradients of ions across cell membranes provide an organized distribution that cells can use in specialized processes. In nerve signaling, changing ion distributions contributes to communication, while in cellular energy production, maintained gradients support the work required to generate usable cellular energy. These roles show why transport and homeostasis are closely connected to membrane gradients.