9TH A-B (SCIENCE) june 23rd, 2010

INSTRUCCIONS

1) FIND THE MEANING OF THE VOCABULARY.

2)DOWNLOAD THE INFORMATION AND PRINTED IT

3)BRING ME THE INFOMATION PRINTED THE NEXT WEEK.


Prokaryotic and Eukaryotic Cells
Living things are made of cells and cell products. In other words, we consider the cell to be a pretty fundamental structural aspect of life.
Cells in our world come in two basic types, prokaryotic and eukaryotic. "Karyose" comes from a Greek word which means "kernel," as in a kernel of grain. In biology, we use this word root to refer to the nucleus of a cell. "Pro" means "before," and "eu" means "true," or "good." So "Prokaryotic" means "before a nucleus," and "eukaryotic" means "possessing a true nucleus." This is a big hint about one of the differences between these two cell types. Prokaryotic cells have no nuclei, while eukaryotic cells do have true nuclei. This is far from the only difference between these two cell types, however.
Here's a simple visual comparison between a prokaryotic cell and a eukaryotic cell:





The cells of plants, fungi and protists are also eukaryotic.
Despite their apparent differences, these two cell types have a lot in common. They perform most of the same kinds of functions, and in the same ways. Both are enclosed by plasma membranes, filled with cytoplasm, and loaded with small structures called ribosomes. Both have DNA which carries the archived instructions for operating the cell. And the similarities go far beyond the visible--physiologically they are very similar in many ways. For example, the DNA in the two cell types is precisely the same kind of DNA, and the genetic code for a prokaryotic cell is exactly the same genetic code used in eukaryotic cells.





This diagram shows a trimmed down prokaryotic cell, including only the plasma membrane and a couple of mesosomes. A mitochondrion is included for comparison: