Introduction to the Plasma Membrane

These flashcards cover essential concepts from the lecture on the plasma membrane, including its structure, function, and mechanisms involved in cell signaling and transport.

What is the Fluid-Mosaic Model composed of?

It is composed of a fluid bilayer made of phospholipids.

What are the characteristics of the phospholipid bilayer?

It is amphipathic, with hydrophilic (polar) heads and hydrophobic (nonpolar) tails.

How does cholesterol affect membrane fluidity at moderate and low temperatures?

At moderate temperatures, it maintains fluidity, and at low temperatures, it prevents the membrane from becoming too rigid.

What are integral (transmembrane) proteins?

Proteins embedded in the membrane that can transport substances in and out of the cell.

What is the function of glycoproteins?

They provide cell 'signature' ID tags.

What does selective permeability mean in regards to the plasma membrane?

Only certain molecules can pass through the phospholipid bilayer.

What is facilitated diffusion?

The process where molecules need assistance from transport proteins to move across the membrane.

What type of solution is ideal for plant cells and why?

Hypotonic solution, as the rigidity of the cell wall prevents bursting.

What is active transport?

The movement of ions against their concentration gradient, requiring energy.

What is the sodium-potassium pump?

An electrogenic pump that actively transports sodium ions out of the cell and potassium ions into the cell.

What is a characteristic of receptor-mediated endocytosis compared to pinocytosis?

Receptor-mediated endocytosis is more specific/selective than pinocytosis.

What occurs during the reception stage of cell signaling?

A signaling molecule binds to a receptor protein, activating it.

What are G-protein coupled receptors (GPCR)?

Membrane receptors that interact with G-proteins to trigger various cellular responses.

What is the significance of second messengers in signaling pathways?

They propagate the signal within the cell after the initial receptor-ligand interaction.

How does cAMP function in signal transduction?

cAMP activates protein kinases in a phosphorylation cascade, resulting in a cellular response.

What is the role of tyrosine kinase receptors in cellular signaling?

They become activated through dimerization and trigger a response by phosphorylating intracellular proteins.