{"id":167,"date":"2022-03-05T18:18:20","date_gmt":"2022-03-05T23:18:20","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/biology1190chemistry\/?post_type=chapter&p=167"},"modified":"2022-04-29T13:52:21","modified_gmt":"2022-04-29T17:52:21","slug":"gradients-and-potentials","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/biology1190chemistry\/chapter\/gradients-and-potentials\/","title":{"raw":"Gradients and potentials","rendered":"Gradients and potentials"},"content":{"raw":"Recall: solutions are homogenous mixtures of a solute in a solvent<\/a>. Sometimes solutes are found at uneven concentrations within a solution. The concentration <\/strong>of a solute in a solution is the amount of solute per volume, usually measured in moles per litre or molarity <\/strong>(M) or as the percent mass of solute per volume (%). If the concentration of a solute is non-uniform within a solution, this results in a concentration gradient<\/strong> within that solution. A gradient<\/strong> refers to a difference in the distribution of matter<\/strong> within a system.\r\n\r\n \r\n\r\n[caption id=\"attachment_488\" align=\"aligncenter\" width=\"620\"]\"Figure Figure 13: Beaker containing a solution with a gradient of solute.[\/caption]\r\n\r\nConcentration gradients are a form of chemical potential energy<\/strong>. This is because solutes tend to move from high concentration to low concentration<\/strong>. This phenomenon is known as diffusion<\/strong> and you will discuss it further in lab and lecture. Solutions move toward even mixing or equilibrium<\/strong>. Therefore, a concentration gradient within a solute represents a chemical potential <\/strong>where the molecules have the potential <\/em>to move to an area of lower concentration within the solution. A potential<\/strong> refers to a difference in the distribution of energy <\/strong>within a system.\r\n\r\nRecall that charged atoms are called ions<\/a>. Ions form a chemical concentration gradient within a solution but they also bear charges. If the charge distribution within a solution is non-uniform, this results in an electrical gradient. <\/strong>Electrical gradients result in one part of the solution being more negatively charged and another part of the solution being more positively-charged. The resulting non-uniform distribution of charge is an electrical potential <\/strong>because negative charges tend to move toward areas of positive charge and vice versa. Ion gradients represent both <\/em>a chemical concentration gradient AND an electrical gradient. The sum of these two gradients is collectively referred to as an electrochemical gradient<\/strong> and the difference in chemical and electrical energy within that system is called an electrochemical potential.<\/strong>\r\n\r\nElectrochemical gradients and the resulting electrochemical potentials are biologically important. Cells actively maintain electrochemical gradients across their membranes to ensure that electrochemical signals can be sent from the brain, along nerves, to muscle and gland cells. Electrochemical gradients across cell membranes ensure that cells can generate energy. You will have a fuller understanding of these processes by the completion of this course.\r\n\r\n
Activity:<\/strong> A salt crystal containing ~10% salt concentration is dropped into different beakers containing saline solutions of varying concentrations. Select an arrow and drag and drop it to the correct position on the diagram below to show what direction salt will move in solution<\/strong>.<\/div>\r\n\r\n[h5p id=\"72\"]\r\n\r\n ","rendered":"

Recall: solutions are homogenous mixtures of a solute in a solvent<\/a>. Sometimes solutes are found at uneven concentrations within a solution. The concentration <\/strong>of a solute in a solution is the amount of solute per volume, usually measured in moles per litre or molarity <\/strong>(M) or as the percent mass of solute per volume (%). If the concentration of a solute is non-uniform within a solution, this results in a concentration gradient<\/strong> within that solution. A gradient<\/strong> refers to a difference in the distribution of matter<\/strong> within a system.<\/p>\n

 <\/p>\n

\"Figure
Figure 13: Beaker containing a solution with a gradient of solute.<\/figcaption><\/figure>\n

Concentration gradients are a form of chemical potential energy<\/strong>. This is because solutes tend to move from high concentration to low concentration<\/strong>. This phenomenon is known as diffusion<\/strong> and you will discuss it further in lab and lecture. Solutions move toward even mixing or equilibrium<\/strong>. Therefore, a concentration gradient within a solute represents a chemical potential <\/strong>where the molecules have the potential <\/em>to move to an area of lower concentration within the solution. A potential<\/strong> refers to a difference in the distribution of energy <\/strong>within a system.<\/p>\n

Recall that charged atoms are called ions<\/a>. Ions form a chemical concentration gradient within a solution but they also bear charges. If the charge distribution within a solution is non-uniform, this results in an electrical gradient. <\/strong>Electrical gradients result in one part of the solution being more negatively charged and another part of the solution being more positively-charged. The resulting non-uniform distribution of charge is an electrical potential <\/strong>because negative charges tend to move toward areas of positive charge and vice versa. Ion gradients represent both <\/em>a chemical concentration gradient AND an electrical gradient. The sum of these two gradients is collectively referred to as an electrochemical gradient<\/strong> and the difference in chemical and electrical energy within that system is called an electrochemical potential.<\/strong><\/p>\n

Electrochemical gradients and the resulting electrochemical potentials are biologically important. Cells actively maintain electrochemical gradients across their membranes to ensure that electrochemical signals can be sent from the brain, along nerves, to muscle and gland cells. Electrochemical gradients across cell membranes ensure that cells can generate energy. You will have a fuller understanding of these processes by the completion of this course.<\/p>\n

Activity:<\/strong> A salt crystal containing ~10% salt concentration is dropped into different beakers containing saline solutions of varying concentrations. Select an arrow and drag and drop it to the correct position on the diagram below to show what direction salt will move in solution<\/strong>.<\/div>\n
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