See also. 1  Concept inventory. 2  Constructive alignment. 3  Educational assessment. 4  Ipsative assessment. 5  Norm-referenced assessment. 6  Psychometrics. 7  Standardized test.
Enveloped viruses have a lipid-based membrane surrounding the protein capsid. This envelope is partly composed of the cell membrane within which the virus replicated, and it contains proteins and carbohydrates. Some of the proteins are from the host cell and some are from the virus..
This fluid lipid bilayer cross section is made up entirely of phosphatidylcholine. The three main structures phospholipids form in solution; the liposome (a closed bilayer), the micelle and the bilayer. The lipid bilayer is a thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around all cells. The cell membranes of almost all living organisms and many viruses are made of a lipid bilayer, as are the membranes surrounding the cell nucleus and other sub-cellular structures.