virus and bactera

cell_diagram_2.pngYour body is made of about 10 trillion cells. The largest human cells are about the dameter of a human hair but most human cells are smaller perhaps one-tenth of the diameter of a human hair.

- maybe 100 microns in diameter (a micron is a millionth of a meter, so 100 micons is a tenth of a millimeter). A typical human cell might be one-tenth of the diameter of your hair (10 microns). -- it might represent 2 or 3 billion cells or so, depending on how big you are. Imagine a whole house filled with baby peas. If the house is your little toe, the peas are the cells. That's a lot of cells!

Bacteria are about the simplest cells that exist today. A bacteria is a single, self-contained, living cell. An Escherichia coli bacteria (or E. coli bacteria) is typical -- it is about one-hundredth the size of a human cell (maybe a micron long and one-tenth of a micron wide), so it is invisible without a microscope. When you get an infection, the bacteria are swimming around your big cells like little rowboats next to a large ship.

Bacteria are a lot simpler than human cells. A bacterium consists of an outer wrapper called the cell membrane, and inside the membrane is a watery fluid called the cytoplasm. Cytoplasm might be 70-percent water. The other 30 percent is filled with proteins called enzymes that the cell has manufactured, along with smaller molecules like amino acids, glucose molecules and ATP. At the center of the cell is a ball of DNA (similar to a wadded-up ball of string). If you were to stretch out this DNA into a single long strand, it would be incredibly long compared to the bacteria -- about 1000 times longer!

I like the grizzle bear because it is a 2nd biggest animal in North America.