Cell Transport Mechanisms

This flashcard set aims to provide senior high school students the necessary supplements for the course material, Cell Transport Mechanisms, in General Biology 1. Disclaimer: This study resource is 100% independent and unofficial; it is not created, endorsed, or affiliated with our school, faculty, or course curriculum. These flashcards are intended strictly for peer-to-peer review and solo study, and they must not be opened or accessed during any quiz, exam, or graded assignment in accordance with academic integrity policies. While every effort was made to ensure accuracy, this material is provided "as-is" by a fellow student, not a textbook. The creator assumes no responsibility or liability for any errors, omissions, or individual academic outcomes, including final exam performance or grades. Please cross-reference these cards with your official syllabus and lecture notes.

Fluid Mosaic Model

This is the representation of the cell membrane as a flexible phospholipid bilayer containing a floating patchwork of proteins, cholesterol, and carbohydrates that move dynamically to regulate what enters and leaves the cell.

Phospholipids

These are the amphipathic molecules that spontaneously self-assemble into a selectively permeable bilayer.

Hydrophilic Heads

These are the charged, polar top segment of a phospholipid composed of glycerol and phosphate that readily interacts with water to form the outer surfaces of the cell membrane.

Hydrophobic Tails

These are the uncharged, nonpolar fatty acid chains of a phospholipid that face inward to form the fluid, water-impermeable core of the cell membrane.

Kink

This is a sharp bend in an unsaturated fatty acid tail caused by a double bond that pushes neighboring phospholipids apart to keep the cell membrane fluid.

Rotation

This is the rapid, 360-degree spinning of a phospholipid around its own long axis that helps keep the cell membrane fluid and dynamic.

Lateral Diffusion

This is the rapid, two-dimensional side-to-side movement of phospholipids and proteins swapping places within the same layer of the cell membrane.

Transversal Diffusion

This is the the slow, enzyme-assisted flipping of a single phospholipid from one layer of the cell membrane to the other.

Cholesterol

This is a rigid steroid lipid wedged between phospholipids that acts as a fluidity buffer, restricting lipid movement in the heat and preventing tight packing in the cold.

Peripheral Proteins

These are the surface-bound proteins that temporarily attach to lipid heads or integral proteins via weak bonds to assist in signaling, enzyme activity, and structural support.

Integral Proteins

These are the permanent, embedded proteins that span into or entirely through the lipid bilayer to serve as transport channels, receptors, and structural anchors.

Channel Proteins

These are the gated or non-gated integral tunnels lined with polar amino acids that allows specific ions and water to diffuse rapidly down their concentration gradient without using ATP.

Carrier Proteins

These are the integral proteins that moves specific molecules across the bilayer by binding them on one side and undergoing a conformational shape change to release them on the other.

Glycoprotein

This is an integral or peripheral protein with attached carbohydrate chains that projects from the outer membrane surface to function in cell recognition, immunity, and cell-to-cell adhesion.

Glycolipid

This is a membrane phospholipid or sphingolipid with an attached carbohydrate chain that sits on the outer leaflet to help maintain membrane stability and facilitate cellular recognition.

Passive Transport

This is the spontaneous movement of molecules across a cell membrane from high to low concentration using natural kinetic energy without spending cellular energy

Simple Diffusion

This is the unassisted movement of small, nonpolar molecules directly across the phospholipid bilayer from high to low concentration without proteins or cellular energy.

Size

This is a factor that affects diffusion in which smaller particles can easily enter and exit the cell.

Polarity

This is a factor that affects diffusion in which difference in electronegativity affects if a substance can easily enter and exit the cell.

Charge

This is a factor that affects diffusion in which unstable molecules cannot enter the cell directly.

Facilitated Diffusion

This is the passive movement of polar or charged molecules across the cell membrane down their concentration gradient through channel or carrier proteins without using cellular energy

Osmosis

This is a type of passive diffusion of water across a selectively permeable membrane toward areas of higher solute concentration without using cellular energy.

Isotonic Solution

A solution that has an equal solute concentration compared to the cell's cytoplasm, resulting in no net water movement in or out of the cell.

Hypotonic Solution

A solution that has a lower solute concentration than the inside of the cell, causing water to flow into the cell and make it swell.

Hypertonic Solution

A solution has a higher solute concentration than the inside of the cell, causing water to flow out of the cell and make it shrivel.

Active Transport

This is the energy-requiring movement of molecules across a membrane against their concentration gradient through transmembrane carrier proteins.

Endocytosis

This is an ATP-dependent bulk transport mechanism where a cell invaginates its plasma membrane to engulf extracellular fluids, macromolecules, or particles into an internal vesicle.

Phagocytosis

This is an ATP-dependent form of endocytosis where specialized cells extend pseudopodia to engulf large solid particles which then fuses with a lysosome for intracellular digestion

Pinocytosis

This is an ATP-dependent form of endocytosis where a cell folds its plasma membrane inward to non-specifically engulf small droplets of extracellular fluid and dissolved solutes into internal vesicles.

Receptor-mediated Endocytosis

This is an ATP-dependent bulk transport mechanism where specific target molecules bind to surface receptors, assembling a clathrin protein scaffold that pinches the membrane inward into a targeted vesicle.

Exocytosis

This is an ATP-dependent bulk transport process where an internal vesicle fuses with the plasma membrane to release its contents into the extracellular space and add lipids to the cell surface.