membranes

• Phospholipids in the membrane have hydrophobic fatty acid tails that form a barrier between the cell and its environment.
• Phospholipids are amphiphatic molecules consisting of a polar head group (hydrophilic) attached to two nonpolar fatty acid chains (hydrophobic).
• Cholesterol molecules are embedded within the phospholipid bilayer, increasing membrane strength and fluidity.
• Plasma membrane has two layers, an inner phospholipid bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward, and proteins embedded within it.
• Hydrophobic fatty acid tails of phospholipids face inward towards the membrane interior while hydrophilic phosphate heads face outwards towards the aqueous environment.
• Phospholipids are the structural components of cell membranes.
• Cholesterol molecules are embedded within the phospholipid bilayer, maintaining membrane fluidity.
• Proteins are embedded within the bilayer or attached to it through covalent bonds.
• Cholesterol helps maintain fluidity by preventing the formation of tight packing of lipid tails.
• The phosphate groups on the heads of these lipid molecules can be negatively charged, which attracts positively charged proteins or other molecules.
• The lipid bilayer is impermeable to water-soluble substances but allows passage of small, uncharged, nonpolar molecules like oxygen and carbon dioxide.
• Glycolipids are similar to glycoproteins but contain carbohydrates linked directly to lipids instead of proteins.
• Proteins play important roles in maintaining the structure and function of biological membranes.
• The plasma membrane is selectively permeable, allowing certain substances to pass through while preventing others from doing so.
• Integral proteins are transmembrane proteins with one or both ends anchored into the lipid bilayer by hydrophobic interactions.
• The plasma membrane is composed of lipids and proteins arranged in a double layer called a phospholipid bilayer.
• Membrane transport involves passive diffusion, facilitated diffusion, active transport, osmosis, endocytosis, exocytosis, pinocytosis, and vesicular transport.
• Lipids make up about half of the mass of the plasma membrane.
• Passive diffusion occurs when particles move down their concentration gradient without energy input.
• Proteins make up about half of the mass of the plasma membrane.
• Glycoproteins are protein molecules with carbohydrates covalently bonded to them.
• Protein molecules can be found on both sides of the plasma membrane or spanning across the entire thickness of the membrane.
• Protein molecules are also present in the plasma membrane, which can be either integral or peripheral.
• Integral proteins have both hydrophobic and hydrophilic regions that allow them to interact with other parts of the membrane.
• Lipids have nonpolar regions that can interact with other nonpolar substances, allowing them to pass through the membrane without being affected by water.
• Glycolipids have carbohydrates on their surface that can be used as antigens by the immune system.
• Membrane proteins have different functions such as transporting substances across the membrane, providing mechanical strength, anchoring organelles, and signaling between cells.
• Water-soluble substances cannot cross the membrane unless they are transported across it by specific carrier proteins.
• Glycolipids are carbohydrates linked to lipids that serve as markers for specific types of cells.
• Larger polar molecules such as glucose cannot pass through the hydrophobic core of the bilayer.
• Transport across the plasma membrane occurs via facilitated diffusion (passive transport) or active transport (requires energy).
• The plasma membrane is the outermost layer that surrounds all cells.
• Phospholipids are amphiphilic molecules with hydrophobic tails and polar heads that form the bilayer structure of the cell membrane.
• The phosphate head group is polar, allowing it to interact with water molecules on both sides of the membrane.
• Facilitated diffusion involves carrier proteins that bind with specific molecules and undergo conformational changes to allow their movement into/out of cells.
• Passive transport does not require energy input and includes simple diffusion, facilitated diffusion, osmosis, and filtration.
• Lipids form an insulating barrier that prevents free movement of polar molecules across the cell surface.
• Membrane fluidity refers to the ability of the lipid bilayer to change shape due to thermal energy.
• Membrane fluidity refers to the ability of the membrane to change shape due to temperature changes.
• Active transport requires energy input and moves substances against their concentration gradient using carrier proteins.