Part 5, Chapter 24 Summary and Analysis

Even the simplest cell is far beyond the ingenuity, or technology, of man. The human body has 10,000 trillion cells, each with their own purpose. Very little of the internal workings of cells are understood. From nerve cells several feet long to tiny disc-shaped red blood cells, most cells live less than a month, but some, like liver cells, may live for years. Brain cells can last a lifetime.

Robert Hooke was the first person to describe a cell. Van Leeuwenhoek identified tiny animals in water using a rudimentary magnifying device. All cells have an outer fatty casing and a nucleus that contains the DNA. Between the two is cytoplasm. Within the cell, literally millions of objects such as lysosomes, endosomes, ribosomes, ligands and peroxisomes are furiously at work, knocking into each other millions of times per day.

Mitochondria are...