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.
The lysosome membrane helps to keep its internal compartment acidic and separates the digestive enzymes from the rest of the cell. 1  Lysosome enzymes are made by proteins from the endoplasmic reticulum and enclosed within vesicles by the Golgi apparatus. Lysosomes are formed by budding from the Golgi complex.