genbio2.1

• It refers to the different pathways and processes a cell must move substances in, out and around itself.

  
  

  Transport Mechanism
• EXOCYTOSIS - process by which cells release particles from within the cell into the extracellular space.
• RECEPTOR MEDIATED - Receptor proteins on the cell surface are used to capture a specific target molecule.
• TRANSPORT MECHANISM - Allow the cell to regulate what solutes enter/exit the cell and the quantity being transported.
• CELL MEMBRANE - Serves as the boundary between the cell's internal and external environments.
• CELL MEMBRANE - Regulates all substances that enter and exits the cell
• CELL MEMBRANE - Exhibits selective permeability, which is why it is referred to as a semi-permeable membrane
• The main body of the plasma membrane is composed of an amphipathic molecule known as a Phospholipid.
• AMPHipATIC-both hydrophobic and hydrophilic
• This unique structure allows the plasma membrane to adopt a bilayer structure wherein the hydrophilic surface is facing both the aqueous external environment and cytosol
• because of its hydrophobic properties the tails form an internal layer These factors cause the plasma membrane to be semi-permeable to certain substances
• The plasma membrane is represented using a model known as the fluid mosaic
• TRANSMEMBRANE PROTEINS - These are proteins that regulate the movement of molecules across the membrane. These proteins form the transport mechanisms of the cell. They are composed of carriers, channels, and receptor proteins.
• CHANNEL PROTEIN - Proteins provide a small hydrophilic passageway for specific molecules and ions
• CHANNEL PROTEIN - Some channels can remain open most of the time leak channels), while others can be opened or closed (gated channels) depending on the presence of a stimulus
• CARRIER PROTEIN - Require the molecule being transported to attach itself to the carrier protein The protein will then change its shape (conformational change to shuttle the molecule across the membrane
• INTERIOR PROTEIN NETWORK - Determines and maintains the structure and form of the plasma membrane. They are responsible for the shape of the cell and the attachment of macromolecules in the membrane
• CELL-SURFACE MARKERS - These are responsible for the recognition of foreign and local (self) cells and tissues.
• PROTEIN AND PROTEIN COMPLEXES - Responsible for the majority of internal and external interactions. There are six (6) classes of membrane proteins. and each serves a specific function:
• Transporters - movement of molecules and solutes across the membrane
• Enzyme - Protein needed by the cell for metabolic functions
• Cell - Surface Receptors - detects chemical messages from environment to elicit reactions
• Cell Surface I.M. - bind to each other for recognition purposes.
• Cell-to-cell Adhesion - bonds and junctions between cells.
• Attachment - it maintain shape, stability and coordinate chemical changes.
• PASSIVE TRANSPORT - This type of transport relies on the concentration gradient of solutes to move them across the plasma membrane.
• PASSIVE TRANSPORT - No energy will be spent to move the solutes across
• SIMPLE DIFFUSION - The movement of ions and molecules from high concentrations to low concentrations is known as diffusion
• Simple diffusion applies to small, non- polar molecules such as oxygen and hormones
• AQUAPORINS - These channels allow water molecules to move across the membrane in large quantities.
• FACILITATED DIFFUSION - lon channels inside aid the charged. ions to move across. Proteins manage and assist the movement of solutes across the membrane.
• OSMOSIS - Water moves in the direction of the solutes until the number of free water molecules is equal, known as osmotic balance. This movement is influenced by the presence of solutes and their ability to pass through the membrane
• TONICITY - The difference in osmotic concentration which leads to the movement of water.
• The solution which has a higher concentration of solutes Is described as hypertonic.
• ACTIVE TRANSPORT - This type of transport mechanism relies on the expense of cell energy. Adenosine triphosphate (ATP).
• ACTIVE TRANSPORT - This expenditure is needed to move molecules against their concentration gradient to maintain internal conditions
• PRIMARY ACTIVE TRANSPORT - lon pumps
• PRIMARY ACTIVE TRANSPORT - Primary active transport is an intentional and uphill mode of transport where a transport protein directly uses energy from ATP phosphorylation.
• What kind of ACTIVE TRANSPORTING is PRIMARY ACTIVE TRANSPORT - (ACCORDING TO ENERGY)
• EXAMPLE of Primary Active Transport - The most common example of active transport is the Sodium-Potassium pump.