C-Notes: Cell Membrane (Plasma Membrane) Stnd: BI 1.a C-Notes: Cell Membrane (Plasma Membrane) 12/2/13 SWBAT describe the functions of proteins in the cell membrane Objective:

Why is the Plasma Membrane called the Fluid Mosaic Model? FLUID- because individual phospholipids and proteins can move side-to-side within the layer, like it’s a liquid. MOSAIC- because of the pattern produced by the scattered protein molecules when the membrane is viewed from above.

What molecules can get through the cell membrane directly? allow SOME materials but not all to pass through the membrane (Semi-Permeable) Fats and oils can pass directly through Movement In: -Food: (sugar, proteins, fats); salts, O2, and H2O Movement Out: Waste: ammonia; salts, CO2, H2) Products: proteins lipid inside cell outside cell salt waste sugar aa H2O

How do cells build a barrier (Membrane) that keeps the watery contents of the cell separate from the watery environment? Membrane is made out of a special kind of lipid (phospholipid) and is double layer (2 layers of phospholipids) “attracted to water”  FATS   LIPIDS  Remember: oil & water don’t mix!! phosphate lipid “repelled by water” inside cell outside cell

Ex: H2O channels, salt channels, sugar channels How does other molecules get through the membrane? The cell membrane makes Protein Channels “doors” through the membrane to allow these specific materials/substances in and out Ex: H2O channels, salt channels, sugar channels inside cell H2O aa sugar salt outside cell waste

Channels are made of proteins How do you build a semi-permeable cell membrane? Channels are made of proteins proteins both “like” water & “like” lipids bi-lipid membrane protein channels in bi-lipid membrane

How do proteins function in the semi-permeable phospholipid bilayer? - Act as doors in the membrane to transport substances in and out of the cell. -Cell recognition -Enzymes to catalyze reactions HIGH LOW

Because molecules move from high to low concentration Why do molecules move through membrane if you give them a channel? Because molecules move from high to low concentration Ex: Diffusion, Osmosis, passive transport, etc

By a process called Endocytosis 3 types of Endocytosis How do larger molecules move into the cell? By a process called Endocytosis 3 types of Endocytosis Pinocytosis “Cell Drinking” most common Takes in dissolved molecules as a vesicles 2. Receptor-Mediated Endocytosis some proteins have receptors on their surface to recognize and take in hormones, cholesterol, etc. 3. Phagocytosis “Cell Eating” - Used to engulf (eat) large particles such as food, bacteria, etc. into vesicles.

copyright cmassengale The Plasma Membrane Pinocytosis 5/11/2019 Most common form of endocytosis. Takes in dissolved molecules as a vesicle. copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/11/2019 Receptor-Mediated Endocytosis Some integral proteins have receptors on their surface to recognize & take in hormones, cholesterol, etc. copyright cmassengale G. Podgorski, Biol. 1010

copyright cmassengale The Plasma Membrane 5/11/2019 Endocytosis – Phagocytosis Used to engulf large particles such as food, bacteria, etc. into vesicles Called “Cell Eating” copyright cmassengale G. Podgorski, Biol. 1010

How do Larger molecules move out of the cell? A process called Exocytosis (opposite of endocytosis) Large molecules that are manufactured (made) in the cell are released through the cell membrane. Inside Cell Cell environment