membrane protiens unit 2 ap bio

Channel protein

An integral membrane protein that forms a hydrophilic channel allowing specific ions or polar molecules to cross the membrane, usually by facilitated diffusion down their concentration or electrochemical gradient.

Carrier protein

A membrane protein that binds a specific substance and changes shape to move it across the membrane. Carrier proteins can be used in facilitated diffusion or active transport.

Transport protein

A membrane protein that helps substances cross the cell membrane. Transport proteins include channel proteins and carrier proteins and can move substances either passively or actively.

Receptor protein

A membrane protein that binds a specific signaling molecule (ligand), such as a hormone, and triggers a cellular response through signal transduction.

Glycoprotein

A membrane protein with a carbohydrate chain attached. Glycoproteins are important for cell-cell recognition and help cells identify other cells.

Enzymatic membrane protein

A membrane protein that functions as an enzyme, catalyzing a specific chemical reaction at or near the cell membrane.

Cell-adhesion protein

A membrane protein that helps cells attach to other cells or to the extracellular matrix, helping maintain tissue structure.

Attachment protein

A membrane protein that connects the plasma membrane to the cytoskeleton inside the cell or the extracellular matrix outside the cell, helping maintain cell shape and organize the membrane.

How do membrane proteins help maintain homeostasis?

They regulate what enters and leaves the cell, receive signals, identify other cells, and help maintain the cell’s structure, allowing the cell to control its internal environment.

How are channel and carrier proteins different?

Channel proteins form hydrophilic passageways through the membrane, while carrier proteins bind substances and change shape to move them across the membrane.

How are receptor and transport proteins different?

Receptor proteins primarily receive signals and trigger cellular responses, while transport proteins move substances across the membrane.

How can a membrane protein be involved in active transport?

A carrier protein or pump can use energy, usually ATP, to move a substance against its concentration or electrochemical gradient.

Sodium-potassium pump

The sodium-potassium pump is a membrane transport protein that uses ATP to move 3 Na⁺ out of the cell and 2 K⁺ into the cell, helping maintain ion gradients and membrane potential.