Cell Membrane PDF
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Uploaded by Kishore
Father Michael McGivney Catholic Academy
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Summary
This document is a presentation or notes on cell membranes. It explains the structure, function, components, and types of proteins found in a cell membrane. The document covers phospholipid bilayers, integral and peripheral proteins, and carbohydrates attached to the cell membrane.
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Cell Membrane Cell Membrane/Plasma Membrane Nickname: “The gatekeeper” Function: Separates the inside of the cell from the external environment Controls the flow of material into and out of the cell 2 Cell Membrane/Plasma Membrane The cell membrane allows only some substances...
Cell Membrane Cell Membrane/Plasma Membrane Nickname: “The gatekeeper” Function: Separates the inside of the cell from the external environment Controls the flow of material into and out of the cell 2 Cell Membrane/Plasma Membrane The cell membrane allows only some substances to pass through it. Therefore, it is called a “semi-permeable” membrane 3 Cell Membrane/Plasma Membrane A cell membrane is made up of: Phospholipid bilayer Proteins Carbohydrates Cholesterol 4 Phospholipid Bilayer The cell membrane is made up of a double layer of phospholipid molecules Phospholipid molecules have two different ends: Hydrophobic tail Hydrophilic head Only other small fat soluble molecules can pass through the phospholipids bilayer on their own 5 Phospholipid Lipid = fat Hydrophilic – water loving Hydrophobic – water hating 6 7 The Fluid Mosaic Model The cell membrane is described to be fluid because of its hydrophobic integral components such as lipids and membrane proteins that move laterally or sideways throughout the membrane. That means the membrane is not solid, but more like a 'fluid'. 8 The Fluid Mosaic Model The membrane is depicted as mosaic because it is like a mosaic that is made up of many different parts The cell membrane is composed of different kinds of macromolecules, such as proteins and carbohydrates 9 Proteins of the Cell Membrane These proteins are like “doorways” in the cell membrane. They let molecules pass through the cell membrane that are not able to pass directly through the phospholipid bilayer. That is, they let larger molecules and non- fat soluble molecules move in and out of the cell. Transport can either be passive (no energy required) or active (requires energy) 10 Types of Cellular Proteins 1) Integral Proteins Imbedded within the bilayer, often going from one side to the other Help with the transport of larger or polar (charged) molecules through the membrane Two types : Carrier and Channel Channel = open tube, usually passive transport Carrier = picked up and spit out, usually active transport Types of proteins Con… 2) Peripheral Proteins Bound to the surface of the bilayer (either inside or out) Can detach and attach depending on the need of the cell Help with cell signaling, act as enzymes, and help provide shape/structure Carbohydrates of the Cell Membrane These are long chains of carbohydrates that are attached to the outside of the cell membrane Carbohydrates help cells recognize other cells and they help cells stick to other cells Glycoprotein – a protein with a carbohydrate attached to it Glycolipid – a lipid with a carbohydrate attached to it 14 Fats in the cell membrane Cholesterol (Steroid) Embedded in the phospholipid bilayer Helps keep fluidity of membrane consistent Reduces fluidity at high temperatures Increases fluidity of membrane at low temperatures Acts as a membrane “antifreeze agent” 15 16
