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Chapter 17 Lipids

Chapter 17 Lipids. 17.8 Cell Membranes. Cell Membranes. Cell membranes separate cellular contents from the external environment consist of a lipid bilayer made of two rows of phospholipids

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Chapter 17 Lipids

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  1. Chapter 17 Lipids 17.8Cell Membranes

  2. Cell Membranes Cell membranes • separate cellular contents from the external environment • consist of a lipid bilayer made of two rows of phospholipids • have an inner portion made of the nonpolar tails of phospholipids with the polar heads at the outer and inner surfaces

  3. Fluid Mosaic Model of Cell Membranes The lipid bilayer • contains proteins, carbohydrates, and cholesterol • has unsaturated fatty acids that make cell membranes fluid-like rather than rigid • has proteins and carbohydrates on the surface that communicate with hormones and neurotransmitters

  4. Fluid Mosaic Model

  5. Transport Pathways Through Cell Membranes The transport of substances through cell membranes involves • diffusion (passive transport), which moves particles from a higher to a lower concentration • facilitated transport, which uses protein channels to increase the rate of diffusion • active transport, which moves ions against a concentration gradient

  6. Transport Pathways Through Cell Membranes (continued)

  7. Learning Check The transport of particles across a cell membrane from high concentration to low concentration is called 1) facilitated transport 2) diffusion (passive transport) 3) active transport

  8. Solution The transport of particles across a cell membrane from high concentration to low concentration is called 2) diffusion (passive transport)

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