TRANSPORT MECHANISM

• Transport mechanisms - systematic ways of material movements in the cell

  • Like a travel protocol
• MNEMONIC

  IATF - Inactive (passive) and Active Transport Facilities

  • serves as its transport mechanisms
• MNEMONICS ON TRANSPORT MECHANISMS

  Diffusion - "Just go with the flow"
• MNEMONICS ON TRANSPORT MECHANISMS

  Osmosis - "Let the water be the driver"
• MNEMONICS ON TRANSPORT MECHANISMS

  Facilitated diffusion - "Take time to travel through tiny tunnels"
• MNEMONICS ON TRANSPORT MECHANISMS

  Active transport - "Power-up the pumps to propel"
• MNEMONICS ON TRANSPORT MECHANISMS

  Bulk transport - "Be carried by the cargo carriers"
• MNEMONICS ON TRANSPORT MECHANISMS

  Endocytosis - "Voyage with the vesicles- the versatile vehicles"
• MNEMONICS ON TRANSPORT MECHANISMS

  Exocytosis - "Make a visit, but be sure to exit (Home sweet home)"
• Cell Transport - refers to the movement of substances across the cell membrane
• The most important feature of a cell's PHOSPHOLIPID MEMBRANES is that they are selectively permeable.
• A membrane that is selectively permeable or semipermeable, has control over what molecules or ions can enter or leave the cell

  • This feature allows a cell to control the transport of materials
• The permeability of a membrane is dependent on the organization and characteristics of the membrane lipids and proteins.

  • In this way, cell membrane help maintain a state of HOMEOSTASIS within cells (and tissues, organ, organ system) so we can stay alive.
• TYPES OF CELL TRANSPORT

  Active and Passive Transport
• Passive transport - involves the movement of material along a concentration gradient (high to low concentration), so it does not require the expenditure of energy
• TYPES OF PASSIVE TRANSPORT

  Simple diffusion - movement of small or lipophilic molecules through the membrane

  • EX: O2, CO2, etc.
• TYPES OF PASSIVE TRANSPORT

  Osmosis - movement of water molecules through the membrane (dependent on solute concentration)
• TYPES OF PASSIVE TRANSPORT

  Facilitated diffusion - movement of large or charged molecules via channel proteins that facilitate the transport

  • EX: ions, sucrose, etc.
• Active transport - involves the movement of materials against a concentration gradient (low to high concentration), so it requires the expenditure of energy

  • EX: ATP hydrolysis
• TYPES OF ACTIVE TRANSPORT

  Carrier proteins or Protein pumps

  • an important adaptation for active transport is the presence of specific carrier proteins or pumps to facilitate active transport
• TYPES OF ACTIVE TRANSPORT

  Bulk transport - like the active transport processes that move ions and small molecules via carrier proteins, it is an energy-requiring (energy-intensive) process, hence it is a type of active transport.
• In bulk transport, the movement of macromolecules such as proteins or polysaccharides into or out of the cell is observed.
• There are two types of bulk transport, EXOCYTOSIS and ENDOCYTOSIS and both require the expenditure of energy (ATP)
• TWO MAIN TYPES OF BULK TRANSPORT

  • Endocytosis
  • Exocytosis
• Endocytosis - is a type of bulk transport, is a cellular mechanism where a cell internalizes substances from the external environment.

  • These substances undergo certain processes of breaking down to smaller elements either for use by the cell or for the elimination purposes.
• In ENDOCYTOSIS, there are 3 types based on the mechanisms of particle:

  • Phagocytosis
  • Pinocytosis
  • Receptor-mediated endocytosis
• Exocytosis - is a type of bulk transport, and a process used to transport materials from inside the cell to the external part of the cell using energy.
• Exocytosis uses special vesicles filled with the particles of interest to transport.

  • a special vesicle bound to the cell membrane, containing the cellular particles will expel the cell content to the external part of the cell.
• PASSIVE TRANSPORT

  • doesn't use energy
  • molecules move from high concentration to low
• ACTIVE TRANSPORT

  • requires energy
  • molecules move from low concentration to high
  • done with the help of proteins called PUMPS
• TYPE OF PASSIVE TRANSPORT

  Diffusion - transport of substances (or solute when in solution)
• TYPE OF PASSIVE TRANSPORT

  Osmosis or diffusion of water - transport the solvent molecules (water)
• TYPE OF PASSIVE TRANSPORT

  Facilitated diffusion - transport of solute with help from membrane proteins

  • Channels
  • Transporters
• Solution = Solute + Solvent
• Diffusion through a permeable membrane follows the concentration gradient of a substance, moving the substance from an area of high concentration to one of low concentration.
• Osmosis - is the diffusion of water molecules (solvent) until the concentration of the solute is equal on both sides of the membrane.
• Direction of water flow in osmosis:

  • From higher concentration of free water molecules to low or from low concentration of solute molecules to high.
• In osmosis, water always moves from an area of higher concentration (of water) to one of lower concentration.

  • In this system, the solute cannot pass through the selectively permeable membrane.
• Hypertonic - solutions with higher concentrations of solute
• Hypotonic - solutions with lower concentration of solute