The Plasma Membrane = The Cell Membrane

The Most Important Job… Maintaining HOMEOSTASIS Homeostasis = internal balance All living cells must maintain balance

How does it maintain homeostasis? The plasma membrane controls what goes in and out Like a good bouncer

How does it maintain homeostasis? a). allow a steady supply of water, glucose, amino acids, and lipids to come into the cell. b). remove excess amounts of these nutrients when levels get so high that they are harmful. c). allow waste and other products to leave the cell.

Selectively Permeable Membrane Allows some substances to cross and not others sugar H2O salt waste lipids

Selectively Permeable Membrane Small uncharged polar particles may pass Large uncharged polar molecules and ions cannot pass

Structure Of The Plasma Membrane

Structure Of The Plasma Membrane Phospholipid bilayer 2 layers of lipids Phosphate head - Hydrophilic - Polar Fatty acid tail - Hydrophobic - Non polar

To make the cell membrane, phospholipids come together to make two layers Which option makes the most sense? WHY? A B C

Structure Of The Plasma Membrane Membrane Proteins Transport channels Chemical receptors Cell to cell communication

Structure Of The Plasma Membrane

Structure Of The Plasma Membrane Cholesterol Keep the phospholipids spaced apart Keeps the membrane fluid/flexible

Structure Of The Plasma Membrane Surface Carbohydrates Cell signaling Cell recognition Cell adhesion

Show me…part of your membrane

Which part forms the bilayer?

Which part helps with transport?

Which part keeps the membrane fluid?

Which part functions in cell signaling?

That is one smelly balloon Eww… That is one smelly balloon

How do the smells get out of the balloons?

The balloon is a semipermeable membrane

Molecules small enough to fit through the “holes” in the balloon diffuse through the membrane

Remember Smelly Balloons? Just like the balloon the cell membrane is selectively or semi permeable This means only some things can diffuse through the cell membrane Now lets talk more about diffusion…

Types of Transport Two types of cellular transport: Passive Active

Passive Transport -Requires NO Energy -Diffusion -Molecules move from an area of HIGH concentration to an area of LOW concentration -With the concentration gradient -Diffusion -Facilitated Diffusion -Osmosis

Important Vocabulary Solute - The solid substance that is dissolved in a solvent. Solvent - The liquid substance in which the solute is dissolved. Solution - The mixture of two or more substances (solute and solvent) in which the molecules of the substances are evenly distributed.

Diffusion The passive movement of molecules from an area of high concentration to an area of low concentration

Fun With Food Coloring

Facilitated Diffusion Diffusion where a protein carrier molecule or channel helps transport molecules across the membrane

Osmosis The diffusion of water across a selectively permeable membrane Water moves from an area of high water concentration to an area of low water concentration Water moves to where there are MORE solute molecules

Where are the solute ions more concentrated? Which way will the Cl- and Na+ ions move?

Hypertonic solution Hypotonic solution Isotonic solution Osmosis occurs in 3 types of solutions. Hypertonic solution Hypotonic solution Isotonic solution

Hypertonic Environment Osmosis = The diffusion of water across a membrane. Water moves OUT Hypertonic Environment An environment with a more solute concentration compared to another 97% NaCl 3% H2O 3% NaCl 97% H2O

Hypertonic Environment Cell will Shrink Hypertonic Environment

Hypotonic Environment Osmosis = The diffusion of water across a membrane. Water moves IN Hypotonic Environment An environment with a less solute concentration compared to another 3% NaCl 97% H2O 97% NaCl 3% H2O

Hypotonic Environment Cell will Lyse (Swell)

Osmosis = The diffusion of water across a membrane. moves IN & OUT Isotonic Environment An environment with equal solute concentration compared to another 3% NaCl 97% H2O 3% NaCl 97% H2O

Isotonic Environment Cell will Stay the same

Which way will the water diffuse? What type of solution is in each beaker? Hypertonic Isotonic Hypotonic

Gummy Bear Lab - Day 1 Not for eating! Okay…maybe when we’re finished

Types of Transport Two types of cellular transport: Passive Active

Active Transport -Requires Energy -Endocytosis -Exocytosis -Molecules move from an area of LOW concentration to an area of HIGH concentration -Against the concentration gradient -Endocytosis -Exocytosis -Protein Pump

Endocytosis and Exocytosis

Exocytosis and Endocytosis are ways a cell can pass proteins out of or into the cell. Exocytosis-a membrane bound vesicle, fuses with the membrane, and releases its contents outside the cell Endoocytosis-the cell membrane engulfs (“eats”) molecules, and takes them into the cell

Use energy to pump ions from low concentration to high concentration Protein Pump Use energy to pump ions from low concentration to high concentration