To show that lines are parallel, we draw small arrow marks on them. In the figure above, note the arrows on the lines PQ and RS. When we write about parallel lines there is a shorthand we can use. We can write which is read as the line segment PQ is parallel to the segment RS.
Lysosome[edit] Lysosomes are spherical bodies, or vacuoles that are enclosed by a single membrane. The membrane serves as a protectorate to the cell, since lysosomes contain harsh digestive enzymes, which would cause significant damage if exposed to cell content.
1 Lysosomes are the main sites of digestion, that is the break-down of structures, within cells. 2  There are, however, some circumstances (diseases/conditions) in which lysosomes begin to 'break-down' living cells-not just useless parts of cells or potentially harmful structures.0nm to 1 Î¼m Â§ , lysosomes have a single outer membrane consisting of a phospholipid bilayer and contain acid hydrolases which are enzymes capable of breaking-down macromolecules. Â§ i.e. 50x10-9m to 1x10-6m, which is the same as 0.00005 to 0.001 mm (millimetres).