Question

in a mammalian cell, by how many mv does the nernst potential of an ion increase if the external ion concentration is doubled?

Answer 1

In a mammalian cell, the Nernst potential of an ion typically increases by about 17.4 mV when the external ion concentration is doubled, as calculated using the Nernst Equation at room temperature (25°C) for monovalent ions.

Step-by-step explanation:

The question relates to how the Nernst potential of an ion changes in a mammalian cell if the external ion concentration is doubled. The Nernst Equation is used to determine the equilibrium potential (also known as the Nernst potential) for an ion, based on the concentrations of that ion inside and outside the cell. Using the Nernst equation, when the concentration of an ion outside the cell is doubled, the equilibrium potential for that ion will change according to the formula:

E = (RT/zF) * ln([ion outside]/[ion inside])

Where:

• R is the ideal gas constant
• T is the temperature in Kelvin
• z is the charge of the ion
• F is Faraday's constant
• ln is the natural logarithm

Since the Nernst equation involves a natural logarithm of the ratio of external to internal ion concentration, when the external concentration is doubled, the change in mV is not simply double but will be calculated based on the natural logarithm of the new ratio. At room temperature (25°C), which is commonly used for these calculations, the equation simplifies, and a doubling of the external concentration typically leads to an increase of about 17.4 mV in the Nernst potential for monovalent ions like Na+ or K+.

Answer 2

The increase in Nernst potential when the external ion concentration is doubled depends on various factors and requires the application of the Nernst equation to determine the exact change in millivolts.

Step-by-step explanation:

In a mammalian cell, if the external ion concentration is doubled, we can calculate the change in the Nernst potential of an ion using the Nernst equation, which is given by:

E = (RT/nF) ln([ion outside]/[ion inside])

Where:

• R is the gas constant (8.314 J/(mol·K))
• T is the temperature in kelvins
• n is the number of moles of electrons
• F is the Faraday constant (96,485 C/mol)
• [ion outside] is the concentration of the ion outside the cell
• [ion inside] is the concentration of the ion inside the cell

If the external ion concentration is doubled, the ratio of [ion outside]/[ion inside] increases, thus increasing the Nernst potential. However, the exact value of the increase in millivolts (mV) depends on the temperature and the charge of the ion involved (n).