Key Components of a Eukaryotic Cell

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Cell (Plasma) Membrane

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A thin, flexible barrier around the cell. Function: Regulates what enters and leaves the cell. Maintains the cell’s internal environment.

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Cytoplasm

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A jelly-like fluid inside the cell that contains salts, nutrients, and organelles. Function: Serves as the site for many metabolic reactions and helps move materials around the cell.

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Nucleus

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A membrane-bound organelle that houses the cell’s genetic material (DNA). Function: Controls the cell’s activities by regulating gene expression and cell division.

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Mitochondria

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Often referred to as the “powerhouses” of the cell. Function: Convert nutrients into ATP (usable energy) through cellular respiration.

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Ribosomes

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Tiny complexes made of RNA and proteins. Function: Carry out protein synthesis (they build proteins from amino acids based on the RNA instructions).

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Endoplasmic Reticulum (ER)

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A network of membranes. Rough ER (with ribosomes attached) helps in protein processing and folding. Smooth ER (no ribosomes on its surface) synthesizes lipids and detoxifies certain chemicals.

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Golgi Apparatus

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A stack of flattened membranes (like pancakes). Function: Modifies, sorts, and packages proteins and lipids for delivery to other parts of the cell or for secretion.

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Vesicles

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Small, membrane-bound sacs. Function: Transport materials (like proteins and lipids) within the cell or out of the cell (exocytosis).

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Lysosomes (Mostly in Animal Cells)

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Small, membrane-bound organelles containing digestive enzymes. Function: Break down waste materials, cellular debris, and foreign invaders (like bacteria).

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Vacuoles (Larger in Plant Cells)

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Fluid-filled sacs. Function: Store water, nutrients, or waste products. In plant cells, a large central vacuole helps maintain cell shape and pressure.