Cells_Cell_membrane_2020.ppt

Cells: The Cell Membrane  The composite/generalized cell All cells have generally three main structures: Cytoplasm A plasma membrane Genetic material  Cell Structures: The plasma membrane The plasma membrane is the defining point of a cell...

Cells: The Cell Membrane  The composite/generalized cell All cells have generally three main structures: Cytoplasm A plasma membrane Genetic material  Cell Structures: The plasma membrane The plasma membrane is the defining point of a cell. It separates the inside of the cell from the outside. Another name for the plasma membrane is the phospholipid bilayer.  The phosopholipid bilayer Let’s break down the phrase phospholipid bilayer. Bilayer= Bi=two Bilayer= two layers Phospho=phosphate Lipid=fat  Has a “head” that contains the choline, a nutrient necessary for building a cell membrane, and phosphate that causes a change in polarity on the cell surface. The head is called hydrophilic because it is designed to touch water.  Has a “tail” that is a chain of fatty acids that are insoluble in water. They are called hydrophobic because the fatty acids avoid water at all costs.  Phospholipid bilayer- a two layer lining of phospholipids that have hydrophilic heads that touch the inside and outside of the cell, and a hydrophobic tail that creates a barrier that defines what stays inside and what stays outside the cell.  The Fluid Mosaic Model of the cell membrane Fluid- movable Mosaic- Structure made up of many different parts. Fluid Mosaic Model- a multitude of different proteins float in the fluid bilayer.  Membrane lipids Glycolipids-lipids with carbohydrate sugars attached. Also act as a cell surface marker.  Transmembrane proteins: Proteins that are in or on the lipid bilayer. Allows the transport of substances and information across the membrane. Interior protein network: provides structural support and helps give membrane its shape. Cell surface marker: self-recognition. Creates glycoproteins and glycolipids that give the cell its own identity.  Transporters: selective; only lets certain substances through. Enzymes: carries out chemical reactions inside the cell membrane. Cell surface receptors: Picks up chemical messages outside of the cell. Glycocalyx: Gives the cell its own “ID” tag. Cell adhesion proteins: allows cells to stick together…literally. Cytoskeletal attachments: surface proteins that interact with other cells are often anchored by the cytoskeleton by linking proteins.  Cholesterol Cholesterol is a steroid found in the cell membrane of all animal cells. Cholesterol is needed to maintain the cell membrane, and can be produced in our bodies, and retrieved in the food we eat.  Membrane junctions Although some cells are considered free- floaters inside the body most cells have some anchoring mechanism to bind themselves together and to other surfaces.