Cell Membrane Structure and Function

These flashcards cover key concepts related to the structure and function of cell membranes, including their composition, transport mechanisms, and the role of various proteins.

Fluid Mosaic Model

A model that describes the structure of the cell membrane as a fluid combination of lipids and proteins.

Selective Permeability

The ability of the cell membrane to regulate what enters and exits the cell.

Phospholipid Bilayer

A double layer of phospholipids that makes up the cell membrane, with hydrophobic tails facing inward and hydrophilic heads facing outward.

Amphipathic

Molecules that have both hydrophobic (water-repellent) and hydrophilic (water-attracting) properties.

Transmembrane Proteins

Integral proteins that span the entire membrane and are involved in transporting substances across the membrane.

Peripheral Proteins

Proteins that are attached to the surface of the cell membrane and do not span the membrane.

Diffusion

The passive movement of molecules from an area of high concentration to an area of low concentration.

Osmosis

The diffusion of water molecules across a selectively permeable membrane.

Hypertonic Solution

A solution with a higher concentration of solute compared to another solution, which can cause a cell to shrink.

Hypotonic Solution

A solution with a lower concentration of solute compared to another solution, which can cause a cell to swell or burst.

Isotonic Solution

A solution where the concentration of solute is the same inside and outside the cell, leading to no net movement of water.

Active Transport

The movement of substances across a cell membrane against their concentration gradient, requiring energy (ATP).

Sodium-Potassium Pump

An active transport mechanism that moves sodium ions out of the cell and potassium ions into the cell against their concentration gradients.

Exocytosis

The process by which a cell expels materials in vesicles that fuse with the plasma membrane.

Endocytosis

The process by which a cell takes in materials by engulfing them in a vesicle derived from the plasma membrane.

Facilitated Diffusion

A passive transport process that uses transport proteins to help move molecules across the cell membrane.

Aquaporins

Channel proteins that facilitate the rapid transport of water across the cell membrane.

Turgor Pressure

The pressure exerted by the fluid in the central vacuole against the cell wall of a plant cell, maintaining its shape and structure.

Plasmolysis

The process in which the cell membrane pulls away from the cell wall due to loss of water in a hypertonic solution.

Cholesterol

A lipid embedded in the animal cell membrane that regulates membrane fluidity across different temperatures.

Glycoproteins

Proteins with attached carbohydrate chains on the cell surface, important for cell-cell recognition and adhesion.

Glycolipids

Lipids with attached carbohydrate chains on the cell surface, important for cell-cell recognition and cell signaling.

Channel Proteins

Integral membrane proteins that form a pore through which specific ions or small molecules can pass.

Carrier Proteins

Integral membrane proteins that bind to specific molecules and change shape to shuttle them across the membrane.

Phagocytosis

A type of endocytosis where a cell engulfs large particles or whole cells.

Pinocytosis

A type of endocytosis where a cell takes in extracellular fluid and its dissolved solutes; also known as "cell drinking".

Receptor-Mediated Endocytosis

A type of endocytosis that uses specific receptor proteins on the cell surface to bind only certain substances.

Proton Pump

An active transport protein that generates an electrochemical gradient by pumping hydrogen ions (protons) out of the cell.

Passive Transport

The movement of substances across a cell membrane down their concentration gradient, without the expenditure of cellular energy.

Primary Active Transport

Active transport that directly uses ATP to move solutes against their concentration gradient.

Secondary Active Transport (Cotransport)

Active transport that uses the energy stored in an electrochemical gradient to move solutes, without directly using ATP.

Electrochemical Gradient

The combined effect of a concentration gradient and an electrical potential difference (membrane potential) across a membrane, influencing the movement of ions.

Membrane Potential

The voltage difference across a membrane, created by differences in the distribution of positive and negative ions.