Cell Membrane

Function/Purpose: Homeostasis 1) Controls what goes in/out of the cell (is semipermeable or selectively permeable) 2) Also acts a barrier to keep the internal metabolism/reactions separate from the outside

Structure Cell membrane is made of phospholipids Has 2 layers so it is referred to as a phospholipid bilayer

Structure Phospholipids have a polar/hydrophilic head and nonpolar/ hydrophobic tail. This causes the double membrane to have a hydrophobic environment on the inside and hydrophilic surfaces on both sides outside

Structure Proteins are scattered throughout the cell membrane, there are 2 types: Peripheral: proteins that only attach to one side of the membrane and do not go all the way across Integral: proteins that span from one side of the membrane to the other

Fluid Mosaic Model The Fluid Mosaic Model states that the cell membrane is like an ocean of phospholipids and proteins, they are able to move around freely

Extracellular Fluid Cytoplasm Phospholipids Cholesterol Integral Proteins Peripheral Protein Cytoplasm

copyright cmassengale The Plasma Membrane 11/9/2018 Cell Membrane The cell membrane is flexible and allows a unicellular organism to move copyright cmassengale G. Podgorski, Biol. 1010

Functions of the Cell Membrane The Plasma Membrane 11/9/2018 Protective barrier – isolates the cytoplasm (intracellular fluid) from the external environment (extracellular fluid) Regulates the exchange of substances (selectively permeable) to maintain homeostasis Cell recognition Communication with other cells G. Podgorski, Biol. 1010

Cell Membrane parts A-phospholipid bilayer B-integral protein C-Glycoprotein E-glycolipid F-fatty acid tails G-phosphate head H-peripheral protein I-cholesterol

Functions of cell membrane parts A-phospholipid bilayer-homeostasis B-integral protein-transport across membrane, spans entire cell membrane C-Glycoprotein-cell communication/recognition E-glycolipid-cell communication/recognition F-fatty acid tails-bilayer,repel water, hydrophobic G-phosphate head- bilayer, attract water,hydrophillic H-peripheral protein-does not span the membrane I-cholesterol –flexibility of membrane