Cell Membrane and Transport

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What is the cell membrane?

Back

The cell membrane is a biological barrier that separates the interior of a cell from its external environment, composed mainly of a phospholipid bilayer with embedded proteins.

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What are transport proteins?

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Transport proteins are proteins that assist in the movement of ions and molecules across the cell membrane, facilitating the transport of substances that cannot pass freely through the lipid bilayer.

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What type of molecules require the help of transport proteins to pass through the cell membrane?

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Polar molecules require the help of transport proteins to pass through the cell membrane.

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What is endocytosis?

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Endocytosis is the process by which cells take in large molecules or particles by engulfing them with the cell membrane, forming a vesicle.

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What is exocytosis?

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Exocytosis is the process by which cells expel large molecules or particles by fusing vesicles with the cell membrane, releasing their contents outside the cell.

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What is active transport?

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Active transport is the movement of molecules across a cell membrane against their concentration gradient, requiring energy (usually in the form of ATP).

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What is simple diffusion?

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Simple diffusion is the passive movement of small non-polar molecules across the cell membrane from an area of higher concentration to an area of lower concentration without the need for energy.

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What is facilitated diffusion?

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Facilitated diffusion is the process by which polar or charged molecules pass through the cell membrane with the help of transport proteins, moving from an area of higher concentration to lower concentration without energy.

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What is osmosis?

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Osmosis is the diffusion of water molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

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What is a phospholipid?

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A phospholipid is a type of lipid molecule that forms the fundamental building block of cell membranes, consisting of a hydrophilic (water-attracting) 'head' and two hydrophobic (water-repelling) 'tails'.