PASSIVE AND ACTIVE TRANSPORT Cell Membrane

4 Main Functions of Cell Membrane Boundary – Separates the cells from each other and their environment Regulator – Controls the exchange of materials that are allowed into and out of the cell Recognition – glycoproteins on the surface help cells identify self from non-self Signaling – allows cells to signal other cells. Cells have proteins called receptors that bind to signaling molecules and initiate a physiological response. Example: Hormones Different receptors are specific for different molecules. Receptors can also respond directly to light or pressure.

Cell Membrane make-up The cell membrane is a double-layered sheet called a lipid bilayer. This layer forms a strong barrier between the cell and its surroundings. Said to be semipermeable or selectively permeable

Picture of Cell membrane

Vocabulary to know Passive Transport – Requires no energy. High concentration to low Active Transport – Does require energy. Low concentration to High

3 Types of Passive Transport 1. Diffusion Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. Ex: spray perfume at the front of the room it will move to the back of the room. Equilibrium – Concentration is the same throughout - Balanced Diffusion does not require the cell to use energy.

Diffusion

2. Osmosis Osmosis is the diffusion of water through a semipermeable membrane Semipermeable - Allowing passage of certain, especially small, molecules or ions but acting as a barrier to others. Solute – That which is dissolved in a solution (eg. Salt in salt water) Water will diffuse from a high concentration of water molecules to an area of lower concentration until equilibrium is reached.

Osmosis

Terms to Know Hyper = More Hypo = Less Tonic = Solute Iso = Equal Solute = What is being dissolved Solvent = What the Solute is being dissolved in Solution = Outside of the cell Cell = inside of the cell

Plant and Animal terms Plant words  Turgid = Full vacuole – pushing out on cell walls  Flaccid = Empty vacuole – wilting  Plasmolysis – Cell membrane moves away from the cell wall leaving gaps – plant only Animal word  Cytolysis (lysis)- Cell bursts due to too much water entering the cell – Animals only  Crenation – cell shrivels

The Effects of Osmosis Higher solute concentration inside cell, more water outside - water goes in Solute concentration same inside & outside cell, water goes in & out Higher solute concentration. outside cell, more water inside – water goes out -Crenation

Effects of Osmosis You Label it IsotonicHypertonic Hypotonic

3. Facilitated Diffusion Molecules that can not cross the lipid bilayer because they are to large (such as glucose) move through protein channels. (doorway) This movement does not require the addition of energy. It still depends on a concentration gradient to exist. Moves from High to low concentration

Types of Proteins 1. Channel proteins - are ion selective, and contain a pore in which solutes pass at high rates when the channel is open. 2. Carrier proteins are the integral proteins which extend into the lipid bilayer of cell membrane, and serve as channels for water soluble substances such as glucose and electrolytes 3. Protein Pumps – discussed during Active Transport.

Facilitated Diffusion

Active Transport Requires the input of energy (ATP) Material moves against the concentration gradient; material moves from an area of low concentration to an area of higher concentration.

3 Types of Active Transport 1. Endocytosis – Taking material into the cell by means of infoldings, or pockets, of the cell membrane.  Phagocytosis – taking in food particles  Pinocytosis – taking in liquid particles 2. Exocytosis – The removal of large amounts of material from the cell. 3. Protein Pump – The protein binds a molecule of the substance to be transported on one side of the membrane, changes shape, and releases it on the other side. The proteins are highly specific, so there is a different protein pump for each molecule to be transported.

Endocytosis & Exocytosis

Macrophages ingesting bacterial by phagocytosis phagocytosis