Cell Membranes & transport of molecules through it KL biology

Functions of cell Membranes 1. Protect cell 2. Control incoming and outgoing substances 3. Maintain ion concentrations of various substances (Calcium, Sodium, etc.) 4. Selectively permeable- allows some molecules in, others are kept out

Prefixes/Suffixes Phospholipid bilayer Hydro- water Hydrophobic tail (lipid) Hydrophilic head (phosphate) Prefixes/Suffixes Hydro- water Philic- being attracted Phobic- fear of

Functions of the membrane

Solutions Solute- substance that’s dissolved (ex. salt or sugar) Solutions are made of a solute and a solvent Solute- substance that’s dissolved (ex. salt or sugar) Solvent- liquid the solute is dissolved in (ex. water)

Solutions

Vocabulary Hypertonic Solution- higher concentration of solute (more molecules) Isotonic Solution- solutions have same concentration of solute Hypotonic Solution- lower concentration of solute (less molecules)

Isotonic Solution Isotonic=Same amount of solute inside the cell as is in the solution its in having equal osmotic pressure as the comparison solution. Same amount of water flows into as flows out of the cell

Hypotonic Solution Hypotonic= greater concentration of solute inside the cell, than outside the cell Cell has a higher osmotic pressure (internally) than a comparison solution turgor pressure- force exerted on the membrane/wall High turgor pressure can cause cytolysis-which is the bursting of cell membranes

Hypertonic Solution Hypertonic= a greater concentration of solute outside the cell, than inside the cell. Cell has a lower osmotic pressure (internally) than a comparison solution Low turgor pressure causes plasmolysis, which is “cell shrinking”. causes plants to wilt

Membrane Transport (Getting molecules Across a cell membrane) 1. Diffusion 2. Osmosis 3. Facilitated Diffusion 4. Active Transport

Diffusion Movement of any type of molecule from high to low concentration Passive Transport- No energy needed So diffusion is a from of passive transport

Diffusion

Membrane Transport (Getting molecules Across a cell membrane) 1. Diffusion 2. Osmosis 3. Facilitated Diffusion 4. Active Transport

Osmosis- water moving through a cell membrane

Membrane Transport (Getting molecules Across a cell membrane) 1. Diffusion 2. Osmosis 3. Facilitated Diffusion 4. Active Transport

Facilitated Diffusion Use proteins to carry molecules across the membrane Like a piggy-back ride

Membrane Transport (Getting molecules Across a cell membrane) 1. Diffusion 2. Osmosis 3. Facilitated Diffusion 4. Active Transport

Active Transport Requires energy(ATP) to transport molecules through the membrane Moving molecules against a concentration gradient Requires the use of “carrier Proteins” Piggy-Back Ride + energy (ATP)

Types of transport

Osmosis- movement of water Remember… Osmosis- movement of water Diffusion, Facilitated Diffusion and Active Transport- movement of molecules

Osmosis labs Vegetable osmoregulation lab Osmoregulation in elodea

Vegetable Osmoregulation Investigation Title: Vegetable Osmoregulation Investigation Problem: How are vegetable samples affected by hypertonic solutions? How are vegetable samples affected by hypotonic solutions? Hypothesis (Prediction): If IV then DV because…   Experimental Design Independent Variable (IV): Levels of IV: Dependent Variable (DV): How will the DV be measured and/or observed? Controlled Variables (2+):

Experimental Control Group: How will you set up the beaker with only experimental controls? Which label will it have?   Experimental Group: How will you set up the beaker that will answer the investigative question?