Cell Transport

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Cell Transport Noun

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[sel trans-port]

Back

Cell Transport

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The movement of substances and materials into and out of a cell across the selectively permeable cell membrane.

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Example: This diagram shows how substances cross a cell membrane, comparing passive transport (like diffusion, which needs no energy) and active transport (which requires energy/ATP).

Front

Cell Membrane Noun

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[sel mem-breyn]

Back

Cell Membrane

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The semipermeable biological barrier surrounding a cell's cytoplasm, regulating the passage of substances into and out of the cell.

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Example: The cell membrane is a flexible barrier made of a phospholipid bilayer with proteins embedded in it that help control what enters and leaves the cell.

Front

Semipermeable Adjective

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[sem-ee-pur-mee-uh-buhl]

Back

Semipermeable

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A property of biological membranes that allows certain molecules or ions to pass through it by diffusion.

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Example: This diagram shows a semipermeable membrane allowing small water molecules to pass through but blocking larger salt molecules, demonstrating its selective filtering function.

Front

Homeostasis Noun

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[hoh-mee-oh-stey-sis]

Back

Homeostasis

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The process by which an organism maintains a stable, constant internal environment despite changes in external conditions.

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Example: This diagram shows how red blood cells transport oxygen from the lungs to the body's cells, a process that helps maintain a stable internal environment (homeostasis).

Front

Phospholipid Bilayer Noun

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[fos-foh-lip-id bahy-ley-er]

Back

Phospholipid Bilayer

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The fundamental structure of the cell membrane, composed of two layers of phospholipid molecules with their hydrophobic tails facing inward.

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Example: This diagram shows the phospholipid bilayer, with a zoom-in on one phospholipid, labeling its water-loving (hydrophilic) head and water-fearing (hydrophobic) tail.

Front

Hydrophilic Adjective

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[hahy-droh-fil-ik]

Back

Hydrophilic

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The physical property of a molecule that is attracted to and tends to be dissolved by water molecules.

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Example: This diagram shows that the 'hydrophilic heads' of phospholipids face the watery environments inside (intracellular) and outside (extracellular) the cell, forming the cell membrane.

Front

Hydrophobic Adjective

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[hahy-droh-foh-bik]

Back

Hydrophobic

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The physical property of a molecule that is repelled from a mass of water and tends to be nonpolar.

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Example: This diagram shows how the 'hydrophobic tails' of molecules avoid water by clustering together, a key principle in how cell membranes are formed.

Front

Passive Transport Noun

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[pas-iv trans-port]

Back

Passive Transport

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

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Example: This diagram shows molecules moving from a high concentration area (extracellular fluid) to a low concentration area (cytoplasm) directly across the cell membrane.

Front

Concentration Gradient Noun

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[kon-sen-trey-shuhn grey-dee-uhnt]

Back

Concentration Gradient

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The gradual difference in the concentration of a substance between two regions, which drives molecular movement.

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Example: This image shows that a concentration gradient is the difference in the amount of a substance (the dots) between two areas, one with a high concentration and one with a low concentration.

Front

Diffusion Noun

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[dih-fyoo-zhuhn]

Back

Diffusion

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The net passive movement of particles from a region of higher concentration to a region of lower concentration.

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Example: Particles, like a smell, naturally move from an area of high concentration (many particles) to an area of low concentration (fewer particles).