 *Remember* - regulates what moves in and out of the cell  Cells transport various molecules ( water, ions, salts, carbohydrates, lipids, proteins, etc) into and out of the cell

 All living cells exist in a liquid environment  Even in the desert, cells of cacti and scorpions are bathed in liquid Most important features of cell membrane is to regulate movement of molecules

 Homeostatsis must be achieved for cells to survive  Raw materials must be taken in  Waste must be removed

 The human body is composed of about 100 trillion cells  Cells range from 1 um – 100 um, with few exceptions  Small cells can exchange substances more rapidly than larger cells

 Materials travel the same speed, no matter the size of cell  Materials entering a larger cell take longer to reach the center

Calculate the SA and V for the following cubes: 1 m x 1m x 1m 2m x 2m x 2m 3m x 3m x 3m

 In phospholipids bilayer – various proteins allow for materials to move in an out of cell  Different types of proteins play a vital role in life of cell

 Marker proteins – attracted to a carbohydrate on cell surface  Helps other cells recognize their cell type – liver cell, heart cell, etc.

 Receptor proteins – recognize and bind to specific substances ( ex: signal molecules outside of cell)

 Transport proteins – aid in the movement of substances into and out of the cell

Diffusion Definition Characteristics ExamplesNon-examples

 Selective permeability – ability of the cell to determine what enters and leaves  Membrane is a highly fluid double layer called the phospholipid bilayer

 Why does the cell membrane have to be selective?

 Head = hydrophilic = which means?  Tails = hydrophobic = which means?

 Marker proteins = identify cells  Transport proteins = transport large particles across membrane  Receptor proteins = capture signal molecules and cause a change in cell behavior

 Describe why an entire room can smell like a candle burning even the smell was all contained in a jar when purchased ?

 In a solution, particles move constantly  Particles move from areas of high concentrations  low concentrations = Diffusion

 Passive transport – materials move down concentration gradient without the use of energy  2 Types: Unassisted: ( diffusion) Protein assisted: ( facilitated diffusion)

 occurs only when materials are transported across the membrane WITH energy

Active Transport - Requires energy - The energy is called ATP - (adenine triphosphate )

 Diffusion Simulation Diffusion Simulation

 In the space provided: create a higher concentration of circle in area 1 and a lower concentration in area 2. Draw an arrow indicating how the molecules.

 Occurs until concentrations are equal on both sides a.) State of equality is called equilibrium - That is what your cells want

 when materials are passing in each direction, but not enough to upset the balance

 diffusion of H2O molecules across the cell membrane

 Aquaporins – channels specific to water

 ---that just means more SALT than WATER MOLECULES!

 Hypo –  Hyper –  Iso -

 a solution with a higher concentration of dissolved particles than the inside of the cell - AKA = LESS WATER in cell

 a solution with a lower concentration of dissolved particles than inside the cell – AKA more water!!

 a solution with the same concentration of dissolved particles as the inside of the cell – AKA same concentration of water  Tonic – dissolved particles, not the water

Type 1: -Cell remains normal size - Equal amount of water inside and outside of cell

 Type 2 -Cell shrinks - More water outside of cell than inside

 Type 3: -Cell Swells - More water inside cell than in solution

Diffusion Osmosis -Movement of materials (proteins, ATP, carbohydrates, etc) -Two types: Unassisted and Assisted (Facilitated Diffusion) -Movement of WATER -Still considered a type of diffusion but just with WATER

Osmosis