Cellular Transport and Ion Concentration

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Questions and Answers

What is the primary purpose of pumping two potassium ions into the cell and kicking out three sodium ions?

To establish a permanent static state in the cell

To facilitate the movement of anions into the cell

To create a concentration gradient for potassium (correct)

To maintain a neutral net charge in the cell

What is the typical charge of the molecules or atoms that potassium ions associate with in the cell?

Negative charge (correct)

Neutral charge

Variable charge

Positive charge

What is the function of the specific channels in the cell membrane?

To allow anions to move into the cell

To allow proteins to move out of the cell

To allow sodium ions to move into the cell

To allow potassium ions to move out of the cell (correct)

What happens to the potassium ions when they leak out of the cell through the specific channels?

They accumulate outside the cell Signup and view all the answers

What is the net charge of the potassium ions and their associated anions in the cell?

Neutral net charge Signup and view all the answers

What is the overall direction of potassium movement in a cell?

Out of the cell Signup and view all the answers

What is the purpose of maintaining a high concentration of potassium ions inside the cell?

To establish a concentration gradient Signup and view all the answers

What is the effect of the potassium ions leaking out of the cell on the concentration gradient?

The concentration gradient decreases Signup and view all the answers

What is left behind when potassium moves out of a cell?

Anions Signup and view all the answers

What is the characteristic of the anions that associate with potassium ions in the cell?

They have a negative charge Signup and view all the answers

What is the term for the negative charge that is generated when potassium moves out of a cell?

Membrane potential Signup and view all the answers

What are the two forces that act on potassium ions in a cell?

Concentration gradient and membrane potential Signup and view all the answers

What happens to the potassium ions when they move outside the cell?

They are attracted to the negative charge inside the cell Signup and view all the answers

What is the point at which the net movement of potassium is zero?

Equilibrium potential Signup and view all the answers

What is the value of the equilibrium potential for potassium in millivolts?

-92 Signup and view all the answers

What is the assumption made in the explanation of potassium movement?

The cell is only permeable to potassium Signup and view all the answers

What is the shape of the curve of potassium movement over time?

_plateau-shaped Signup and view all the answers

What is the relationship between the concentration gradient and membrane potential?

They are opposing forces Signup and view all the answers

What is the primary reason why the concentration of potassium ions is not considered to be significantly changed?

The number of moles of potassium ions is extremely large Signup and view all the answers

What is the result of potassium ions moving out of the cell?

The concentration of potassium ions inside the cell decreases Signup and view all the answers

What is the significance of the number 6.02 times 10 to the 23rd?

It is a fundamental constant in chemistry Signup and view all the answers

What is the purpose of multiplying 6.02 times 10 to the 23rd by 5?

To demonstrate the enormous number of potassium ions Signup and view all the answers

How many potassium ions are required to create a negative charge?

A handful of ions Signup and view all the answers

What happens to the concentration of potassium ions inside the cell if some ions move out?

It decreases slightly Signup and view all the answers

Study Notes

Creation of Concentration Gradient

A concentration gradient of 5 millimoles per liter of potassium is created by pumping in 2 potassium ions and kicking out 3 sodium ions.

Ion Distribution and Anions

Potassium ions find anions (negatively charged molecules or atoms) to sit next to, resulting in a neutral net charge.
Anions can be proteins, chloride, phosphate, or other molecules with a negative side chain.
Potassium ions are not alone in the cell, but accompanied by anions.

Ion Channels and Leakage

There are little gaps in the cell membrane, allowing potassium ions to leak out through specific channels.
These channels only allow potassium ions to pass through, not anions or other molecules.

Concentration Gradient and Membrane Potential

The concentration gradient drives potassium ions out of the cell.
The movement of potassium ions out of the cell leaves behind anions, generating a negative charge.
The negative charge creates a membrane potential that attracts potassium ions back into the cell.
The concentration gradient and membrane potential are opposing forces.

Equilibrium Potential

The concentration gradient and membrane potential eventually reach equilibrium, where the net movement of potassium ions is zero.
At this point, the membrane potential is approximately -92 millivolts for potassium ions.
The equilibrium potential depends on the specific ion and the cell's permeability.

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Description

Learn about the energy-dependent process of establishing a concentration gradient in cells, particularly the exchange of potassium and sodium ions. Understand how this gradient is maintained and its significance in cellular functions.