myelin sheath
virus~
a very thin membrane, composed of lipids and protein, that surrounds the cytoplasm of a cell and controls the passage of substances into and out of the cell
Ribosomes are composed mainly of protein and RNA.
a capsid
White matter in the nervous system is caused when the axons in the area are myelinated. This means that the axons have a fatty protein covering to provide insulation. The myelin sheath is composed of special cells calls Schwann Cells.
Ribosomes are composed of protein and RNA.
Fingernails and hair (and claws, hooves and horns on animals) is composed of a protein called "Keratin".
thick filaments
protein
simple protein and non protein substance.
Ribosome.