15. Cell Membrane And Glycoclaix, Cell Membrane Models. Flashcards
Cell membrane
What is the average thickness of the cell membrane? Is it symmetrical in most cases?
The average thickness of the cell membrane is between 8-10 nanometers. It’s asymmetrical In most cases.
What is the chemical composition of the cell membrane? How much of the cell membrane is lipids? Can you name some of them? How much Of it is proteins? Can you name some of them? How much of the cell membrane is carbohydrates? Can you name some of them?
The cell membranes chemical composition is made with proteins, lipids and carbohydrates. There is between 20-40% lipids. Some of them are phospholipids, steroids and glycolipids. There is around 50% proteins in the cell membrane some of them are enzymes, structural proteins and enzymes. There’s around 10% carbohydrates in the cell membrane. Some of them are glycoproteins, glycolipids, glycocalyx.
Functions of the cell membrane.
What are the cell membranes functions? Describe how it communicates. Describe the intercellular connection. Describe the physical barrier of the cell membrane. Describe it’s selective permeability.
The main functions of the cell membrane is communication, intercellular connection, physical barrier and selective permeability. The cell membrane contains receptors that recognises and responds to molecular signals. It also has intercellular connection where it establishes a flexible boundary, protects the cells contents and supports its structure. The physical barrier is the phospholipid bilayer that separates substances inside and outside the cell. It is also semi permeable which means it regulates entry and exit of ions, nutrients, and waste molecules through the membrane.
Glycocalyx
What is the glycocalyx? Who discovered it? What’s the thickness of the glycocalyx? How often is it renewed? What’s it’s chemical composition? What’s the functions of the glycocalyx? Is it involved in protecting the cell? Is it involved with absorbing anything? Does it connect cells? Does it have something to do with foreign particles? Does it have a immunological role?
The glycocalyx is the superficial surface layer that cover the cell membrane and it’s derivatives. It was first observed by Yamada in 1955. The thickness can be up to 100 nanometers. It is renewed rapidly between 6-8 Hours. The chemical composition of the glycocalyx is glycolipids, glycoproteins and proteoglycans. It has several important functions. The glycocalyx work as a defence barrier for the cell. It is involved with absorbing molecules to the cell surface. It’s involved with cell adhesion. It recognises foreign particles. The glycocalyx is involved in identifying antigens on the cell surface of the cell membrane.
Cell membrane models
Who first forwarded the fluid mosaic model? Can you describe how it’s formed? What does it primarily consist of? What kind of layer does the lipids form? What does ampiphatic mean? How are the the fatty acid chains and phosphate head structure? What is a integral protein? What is a peripheral protein? Why is it called a fluid mosaic model? Can you name other models? Describe its theory shortly?
The cell membrane was first forwarded by singer and Nicholson. It primarily consists of phospholipids, cholesterol and protein molecules. The lipids form a lipids bi layer that is ampiphatic. It means that it is both hydrophobic and hydrophilic. The fatty acid chains face each other because they are hydrophobic and it also makes the inner portion hydrophobic the surface is formed by phosphate head which are hydrophilic. A integral protein is proteins that are embedded within the protein or pass through it completely and most of the proteins are integral. Peripheral proteins are active molecules formed from amino acids which interact on the surface of the lipid bi layer of the cell membrane. It is called a fluid mosaic model because the lipids are in a semi fluid like state. Another cell membrane model is Charles Ernest Overton’s concept. He’s theory was that the cell membrane was a lipid-impregnated barrier layer.
