CELLULAR TRANSPORT MECHANISM

• Cell membrane


  Also known as the "gatekeeper of the cell", it is a semipermeable membrane that regulates what goes in and out of the cell and separates the content of the cell from the outside environment
• Components of the cell membrane

  • Phospholipids
  • Cholesterol
  • Integral proteins
  • Peripheral proteins
  • Carbohydrates
• Phospholipids


  • The cell membrane is made up of a phospholipid bilayer which consists of a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail, its main function is to become semipermeable
• Cholesterol


  • It is located between the phospholipid molecules, its main function is to lessen the fluidity of the phospholipid and prevent them from becoming too stiff
• Types of proteins in the cell membrane

  • Integral proteins
  • Peripheral proteins
• Integral proteins


  • Embedded within the bilayer, their main function is to transport molecules in and out of the cell. There are two types: channel proteins and carrier proteins
• Peripheral proteins


  • Attached to the surface of the bilayer, their main function is to help in cell signaling and cell communication
• Carbohydrates


  • Also known as sugar molecules, they are located on the exterior of the surface of the bilayer, their main function is to promote cell recognition. There are two types: glycoproteins and glycolipids
• Transport mechanism


  The movement of specific substances in and out of the cell, there are two major types: passive transport and active transport
• Passive transport mechanisms

  • Diffusion
  • Osmosis
  • Facilitated diffusion
• Active transport mechanisms

  • Primary active transport
  • Secondary active transport
  • Bulk transport (exocytosis and endocytosis)
• Diffusion


  Substances move from an area of higher concentration to lower concentration until the concentration is equal across the space
• Examples of diffusion


  • Food coloring in cold water
  • Tea particles in hot water
  • Perfume particles in air
• Osmosis


  The diffusion of water across a semipermeable membrane, where water moves from an area of higher concentration to lower concentration
• Types of osmotic solutions

  • Hypertonic
  • Hypotonic
  • Isotonic
• Examples of osmosis


  • Dried raisins in water
  • Plant roots in soil
  • Egg in vinegar or honey
• Facilitated diffusion


  Diffusion aided by transport proteins, there are two types: channel proteins and carrier proteins
• Primary active transport


  Directly dependent on ATP, moves ions across a membrane and creates a difference in charge across that membrane. The sodium-potassium pump is an important example
• Sodium-potassium pump


  1. Sodium ions bind to carrier proteins

  2. ATP is split and phosphate is released

  3. Sodium ions are released outside the cell

  4. Potassium ions bind to carrier proteins

  5. Carrier protein changes shape

  6. Potassium ions are released inside the cell

  7. Phosphate is removed from carrier protein
• Secondary active transport


  The transport of a solute that does not directly require ATP, brings in sodium ions (typically Na+ or H+) and other compound materials against its concentration gradient. There are three types: uniport, antiport, and symport
• Bulk transport mechanisms

  • Exocytosis
  • Endocytosis
• Exocytosis occurs when materials are being transported outside the cell
• Endocytosis occurs when materials are being transported inside the cell
• Phagocytosis takes in solid particles, pinocytosis takes in fluids
• cell membrane


  also known as the gatekeeper of the cell
• cell membrane


  semipermeable that regulates what goes in and out of the cell
• cell membrane


  separates content from outside environment
• phospholipids

  cell membrane is made up of bilayer which consist of hydrophilic (water-loving) head and hydrophobic (water-fearing) tail
• phospholipids


  main function is to become semipermeable
• cholesterol


  located between phospholipids molecules
• cholesterol


  main function is to lessen the fluidy of the phospholipid molecule and prevent it from becoming too stiff
• protein


  second major component of the cell membrane
• integral protein


  embedded within the bilayer
• integral protein


  main function is to transport molecules in and out of the cell
• channel protein


  doesn't change shape and doesn't need energy
• carrier protein


  changes shape and need energy
• peripheral protein


  attached in the surface of the bilayer
• peripheral protein


  help in signaling and cell communication
• carbohydrates


  also known as sugar molecules
• carbohydrates


  located at the exterior of the surface of the bilayer, promote cell recognition