1.5 plasma membrane

• the 2 main compartments in the plasma membrane are proteins and phospholipid bilayer
• The first layer (phospholipid bilayer) is made up of phospholipids and is a single layer
• the first layer also has hydrophobic (doesn’t like water) tails and hydrophilic (likes water)heads which create a hydrophobic barrier
• the 2nd layer or proteins embedded within this bilayer and has a mosaic like appearance.
• Phospholipids are the main component of cell membranes. they are made up of a glycerol backbone, a phosphate group and two fatty acid tails
• there are 3 types of proteins, integral, trans membrane proteins and peripheral proteins
• integral proteins are imbedded in the bilayer and are exposed in both side of the membrane.
• trans membrane are proteins that span the plasma membrane but have parts exposed in the interior and exterior of the cell.
• peripheral are proteins that are posed to the exterior of the plasma membrane through bonding with lipids (fats) or through interactions with integral proteins.
• there are 6 functions of proteins
• they are TRACIE
• T-Tranport

  R-reception

  A-anchorage

  C-cell identity

  I-intercellular joining

  E-enzymatic activity
• t- they control the movement of substances within the bilayer and are involved in the transport of substances in and out of the cell.
• r-trans membrane proteins on the outer surface ae the receptors of the significant molecules. each cell has diffident types of these proteins
• a: proteins connect the cytoskeleton to the xtra cellular matrix holding cells in place. they make sure that nearby cells dont float away.
• C- cell identity is important and proteins do this by labelling cells as ‘self’ in order to distinguish them from foreign cells.
• i- these proteins ate involved ion the taught functions and joining cells together and facilitate communication between cells. this is particularly important for the functioning of tissues.
• e-for reactions to occur, there needs to be a source of energy to break chemical bond.s enzymes help here by speeding up reactions and controlling biochemical pathways.
• States of matter ( low-> high)

  
• Functions of the plasma membrane

  1-is an active and selective boundary

  2-denotes cells identity

  3-receives external signals

  4-transports materials
• substances that try to get into the plasma membrane can be separated into 2 groups.
• hydrophilic: dissolve in water (love water)
• hydrophobic: dissolve in fats (hates water)
• they can also be distinguished by their size and concentration gradient
• stuff that can get in and out

  yes- small unchanged polar molecules, ethanol and gases

  no- charged polar molecules, ions, larger uncharged polar molecules, amino acids, atp, glucose, phosphate
• there is 2 types of transport in the plasma membrane. passive and active
• concentration gradient: occurs when there is a difference insolute concentration from one area to another.
• movement of high region of concentration to low= down along the concentration gradient
• region of low to high= against the gradient
• Transport along plasma membrane zoom in btw

  
• Facilitated diffusion is where lipids repel molecules that struggle to get inside the bilayer
• channel proteins are trans membrane proteins that are involved in the transport of substances via facilitated diffusion
• osmosis is the diffusion in water across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.
• isotonic- both sides of the membrane having the same amount of solutes per water and the same amount will diffuse in and the same amount will diffuse out too.
• hypertonic- having a higher concentration of dissolved substances than the solution
• active transport- movement of molecules from a low concentration to a high concentration through a membrane and in the opposite diurection to diffusion. this can only happen if the energy source is atp.
• endocytosis: the bulk movement of solids or liquids into a cell through engulfment.
• Hypertonic is plasmolyzed (plant) and shriveled (animal)
• Hypotonic is turgid (plant) and lysed (animal)
• Isotonic is flaccid (plant) and normal (animal)