Cell Metabolism and Membrane Permeability

This set of vocabulary flashcards covers the fundamentals of cell metabolism, membrane structure, and the specific mechanisms of molecular transport through the lipid bilayer.

Cell metabolism

The set of chemical reactions occurring within a cell, involving the intake of required materials and the elimination of produced wastes.

Selectively permeable

A property of plasma membranes that allows them to regulate molecular traffic by permitting certain substances to cross while preventing others.

Hydrophobic nonpolar molecules

Substances such as hydrocarbons that can dissolve in the lipid bilayer of the membrane and cross it easily.

Phospholipid bilayer

The main component of the plasma membrane, consisting of hydrophilic heads and hydrophobic tails that create a barrier.

Nonpolar covalent bonds

Chemical bonds where electrons are shared equally between atoms because the atoms are the same element or the molecule has a balanced linear structure.

Oxygen ($O_2$)

A small, nonpolar molecule with a double bond that can diffuse across the cell membrane because its electrons are shared equally.

Carbon dioxide ($CO_2$)

A small, hydrophobic, and linear molecule with two double bonds that can diffuse across the cell membrane due to equal electron sharing.

Polar molecules

Substances such as sugars or ions that do not cross the membrane easily because they have a charge that cannot pass through the hydrophobic tails of the lipid bilayer.

Transport proteins

Proteins embedded in the phospholipid bilayer that provide a way of passage, such as a tunnel or a shuttle, for specific atoms, ions, or molecules.

Sodium ion ($Na^+$)

An ion with a $+1$ positive charge that requires a specific transport protein to cross the plasma membrane.

Channel proteins

A type of transport protein that has a hydrophilic channel that certain molecules or ions can use as a tunnel to cross the membrane.

Aquaporins

A specific type of channel protein that allows only water ($H_2O$) molecules to pass through the cell membrane.

Carrier proteins

Transport proteins that bind to specific molecules or ions and change shape to shuttle them across the membrane.

Potassium ion ($K^+$)

An ion with a $+1$ charge that can be moved across the membrane by a specific carrier protein that undergoes a shape change when the ion binds.