Ch. 4- Membrane Structure & Function

1. Ch. 4- Membrane Structure & Function Ch. 4.1- Plasma Membrane Structure & Function

2. Target #1- I can identify the functions of the plasma membrane • Define boundaries and serve as permeability barriers • Keeps desirable substances in and undesirable substances out • Site of specific proteins and therefore have specific functions • Proteins help to determine the type of cell as well as organelles inside the cell • Proteins regulate the transport of substances • Proteins detect and transmit electrical and chemical signals • Molecules attach to specific proteins called receptors • Relays a message to the cell through these proteins • Proteins mediate cell adhesion and cell-to-cell communication • Allow for the exchange of cellular components

3. Target #2- I can describe the Fluid-Mosaic Model • Fluid Mosaic Model • Describes the arrangement of the molecules that make up a cell membrane • The membrane is flexible • the phospholipids can move side-to-side and past each other • Membrane behaves like a fluid • The variety of molecules studding the membrane is similar to the arrangement of mosaic tiles

4. Target #3- I can describe the components of the plasma membrane • Phospholipid structure • The polar heads form bonds with water inside and outside the cell • The non-polar and polar properties of the phospholipids means they arrange themselves in layers • Integrated Molecules • Sterols • Cholsterol: A sterol found in animal cells • Phytosterol: A sterol found in plants • Provides support and strength to the plasma membrane • Helps to regulate fluidity

5. Target #3- cont • Proteins • Consists of peripheral and integral proteins • Peripheral proteins • Associated with only one side of the plasma membrane • Peripheral proteins located inside the cell are held in place by the cytoskeleton • Integral proteins • Span the membrane, and protrude from one or both sides • Can move laterally, and can change their position in the membrane • Carbohydrates • Occur only on the outside of the cell • If attached to a protein= glycoprotein • If attached to a lipid= glycolipid

6. Target #4- I can Differentiate between peripheral and integral proteins • Peripheral proteins have a structural role • Help stabilize and shape the plasma membrane • Involved in signaling pathways • Integral proteins determine a membrane’s specific functions

7. Target #5- I can describe the function of the 5 types of peripheral proteins • Channel Proteins • Involved in the passage of molecules through the membrane • Has a channel that allows a substance to move across the membrane • Example • Allows hydrogen ions to travel into the mitochondria to assist with ATP production • May contain a gate that must be opened by the binding of a specific molecule to the channel

8. Target #5- cont • Carrier Proteins • Involved in the passage of molecules through the membrane • Combine with a substance and help it move across the membrane • Example • Movement of sodium through neurons to facilitate conduction for electrical impulses

9. Target #5- cont • Cell Recognition Proteins • Aka: glycoproteins • Help the body recognize when its being invaded by pathogens to trigger an immune response • Receptor Proteins • Allows specific molecules to bind to it • The binding of this molecule causes the protein to change its shape • causes a cellular response • Enzymatic proteins • Carry out metabolic reactions directly • Example • Respiration