The Cell Membrane Chapter 2 Section 2.1- The Components of Cells Topics: Structure, Function, Diseases
Why is the cell membrane so important? Controls what molecules enter and leave Selectively permeable O 2, CO 2, and water can pass straight through membrane Charged or larger molecules need channel or carrier proteins to enter.
What are the parts of a cell membrane? Phospholipids – Create a bilayer – Phosphate head Hydrophilic- loves water so exposed to watery internal & external cell environment – 2 lipid tails Hydrophobic- hate water so are found in the middle of the membrane
What are the parts of a cell membrane? Glycoproteins- carbohydrate chains attached to proteins embedded in CM Glycolipids- carbohydrate chains attached to phospholipids embedded in CM Both of these help other cells recognize each other
What are the parts of a cell membrane? Receptor Proteins – Have indentations or shapes that fit and hold molecules outside the cell. – Ligand- molecule that binds to the active site of a receptor – After ligand binds to receptor a cascade of chemical reactions occur inside cell – EX: Ligand might send a message inside the cell to tell cell to make more mucous, hormone, etc.
What are the parts of a cell membrane? Selective channel protein- allows certain ions into/out of cell; like a tube for passive movement of larger or charged ions Adhesion proteins- connect two bilayers to each other Enzymes- speed up chemical reactions Carrier protein- open and close to dump molecules in/out Carrier protein clip
What are the parts of a cell membrane? Cholesterol – gives cell membrane some structure so it is not “mushy” – Keeps cell membrane from freezing in cold weather
Why is the cell membrane called a fluid mosaic model? Mosaic- b/c it is studded with so many different proteins, carbohydrates, enzymes, etc. Fluid- b/c the molecules are not rigidly joined. They are moveable around each other Fluid Mosaic Video Clip
Cell Membrane Rap!
What types of diseases are associated with proteins in the cell membrane? Congenital Insensitivity to Pain (CIP)- – sodium channel proteins are mutated and block sodium ions which leads to decreased or absent nerve impulses – No nerve impulses= can’t feel pain Normal Sodium Channel Video Clip
What types of diseases are associated with proteins in the cell membrane? Paroxysmal extreme pain disorder (PE or PEPD) – Sodium channel proteins are mutated and left open too long causing a prolonged and intense pain response
What types of diseases are associated with proteins in the cell membrane? Cystic Fibrosis (CF) – Abnormal sodium and chloride channel proteins – Sodium chloride trapped inside cell draws water out of mucous lining lungs/pancreas which causes mucous to be very thick. – CF patients have difficulty breathing due to thick mucous secretions in pancreas and lungs, & frequent lung infections