Chapter 3 Flashcards
What is the plasma membrane?
The plasma membrane is a semi permeable phospholipid bilayer that seperates the intracelullar environment and the extracellular environment. It is embedded with cholesterol to regulate fluidity, carbohydrates for cell signalling, and multi functional proteins
What are phospholipids?
The main component of the phospholipid bilayer. They have a phosphate head, which is hydrophillic, and 2 fatty acid tails that are hydrophobic. They arrange in pairs, with the tails pointing inwards and the heads pointing outwards- forming the billayer
What is cholesterol?
A lipid steroid embedded in the phospholipid billayer that regulates the fluidity of the membrane. At higher temperatures the cholesterol keeps the phospholipid bound together, whereas in low temperatures the cholesterol keeps the membrane fluid and prevents it from forming a solid boundary
What are carbohydrates?
usually in chains outside the cell, rooted in the membrane to lipids ( glycolipids), or proteins ( glycoproteins). They aid with cell to cell communication, signalling, recognition of self/ non self molecules, and adhesion
What are integral proteins?
proteins that are a permenant part of the membrane, aids with transport, channels or pumps, that control what enters and exits the cell
What is a transmembrane protein?
an integral protein that spans from the inside to the outside of the bilayer
What is a peripheral protein?
Temporary proteins that attach to the outside of the membrane
What is the cytoskeleton?
the microscopic web of protein filaments in the cytoplasm. It provides structure, support, and transports products around the cell
What does the fluid mosaic model mean?
describes the fluid nature of the phospholipid, which is composed of phospholipids, proteins and carbohydrates which looks similar to a mosaic
What does polar mean?
polar describes a molecule with both a positive end a negative end. These tend to be hydrophillic
What does nonpolar mean?
nonpolar describes a molecule without a clearly positive or negative end. These tend to be hydrophobic
What is passive transport?
The movement of molecules across a membrane without the use of energy. Diffusion, facilitated diffusion, and osmosis are three types of passive transport
What is diffusion?
The passive movement of molecules from an area of high concentration to an area of low concentration (down the concentration gradient).
Small, nonpolar molecules most commonly use this means of transport
What is facilitated diffusion?
The passive movement of molecules down their concentration gradient through a membrane protein. This occurs to large and/ or polar molecules like glucose. The charge, and size of these proteins means they can’t diffuse easily through the plasma membrance, instead they must go through a protein channel or protein carriers.
What is a protein channel?
pores or holes in the plasma membrane that let a specific substance through. They open or close depending on whether that cell requires that substance or not
