Cell Membrane Structure Flashcards
Structure of triglyceride lipid molecules and properties
Made up of three fatty acids and a glycerol. They are non polar and hydrophobic so insoluble in water
Structure of phospholipids and properties
Made up of two fatty acids, a glycerol and a phosphate.
-the phosphate head is polar so hydrophilic and slightly positive while rest is slightly negative. Fatty acid tails non polar so hydrophobic
When added to water how do phospholipids become arranged
Arranged with no contact between hydrophobic tails and water-can form layer on surface with hydrophobic tails directed out of water
-can form spherical clusters(micelles)
-can form bilayer- hydrophobic tails have no contact with water on either side of membrane and hydrophilic phosphate heads remain in contact with aqueous environ
Components that make up the cell surface membrane
-phospholipid bilayer
-proteins
-cholesterol
-glycolipids
-glycoproteins
Why is the model referred to as a fluid mosaic
-fluid refers to the movement of phospholipids and other components in the plane of the membrane
-mosaic refers to random association of proteins of dif shapes and sizes within the membrane
What are peripheral proteins
Proteins loosely attached on the outside surface of the membrane
What are integral proteins
Proteins that are fully embedded within the phospholipids
Role of peripheral proteins
Act as receptors and allow cells to detect chemicals released from other cells meaning it can respond
What is a glycoprotein
A protein with a carbohydrate attached
What is a glycolipid
A lipid with a carbohydrate attached
Role of glycolipids and glycoproteins
-act as an antigen to facilitate cellular recognition-recognise ‘self’ which is crucial to immune response
-signalling and communication with other cells(cell adhesion)- for orientation ensuring cell is in correct position
Role of cholesterol in the cell membrane and where it is found
Binds to phospholipid tails which gives stability by restricting movement of molecules in membrane, causes tails to pack together creating a barrier to polar substances stopping them from moving through the membrane
-regulates fluidity of the membrane
Why do red and white blood cell membranes contain a lot of cholesterol
They are not supported by other cells as they are unsupported and free-floating cells meaning the cholesterol provides support
Four functions of membranes at the surface of cells
-separate organelles from cytoplasm=metabolic reactions can happen
-provide surfaces for reactions
-surface antigens are important in immune system as recognise cell as self
-control entry and exit of materials in organelles and cells
