Cell Transport

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Cell Transport Noun

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[sel trans-port]

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Cell Transport

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The movement of materials and substances across the cell membrane, which is essential for a cell's survival and function.

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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).

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Cell Membrane Noun

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[sel mem-breyn]

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Cell Membrane

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The semipermeable biological barrier surrounding a cell's cytoplasm that regulates 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 a membrane that allows certain molecules or ions to pass through it but prevents the passage of others.

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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.

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Homeostasis Noun

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[hoh-mee-oh-stey-sis]

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Homeostasis

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The process by which an organism or cell 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]

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Phospholipid Bilayer

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The fundamental structure of the cell membrane, composed of two layers of phospholipids 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.

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Hydrophilic Adjective

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[hahy-druh-fil-ik]

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Hydrophilic

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The property of a molecule, described as 'water-loving,' that causes it to be attracted to and dissolve in water.

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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.

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Hydrophobic Adjective

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[hahy-druh-foh-bik]

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Hydrophobic

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The property of a molecule, described as 'water-fearing,' that causes it to repel or fail to mix with water.

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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.

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Passive Transport Noun

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[pas-iv trans-port]

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Passive Transport

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The movement of substances across a cell membrane down the concentration gradient without the use of cellular energy (ATP).

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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]

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Concentration Gradient

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The gradual difference in the concentration of a substance between two areas, which drives movement from high to low concentration.

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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]

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Diffusion

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The net movement of molecules or atoms 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).