Eukaryotes are organisms that consist of cells with nuclei. Every cell has a cell membrane, which is a thin double layer of lipids that maintains a chemical difference between the inside of a cell and the outside; cytoplasm, which is the liquid contents of a cell with its suspended components; ribosomes, which make proteins; and DNA, which stores genetic information. The simplest cells (though by no means simple) are the prokaryotic cells which have very little more than this. Most bacteria have, in addition, a cell wall and some bacteria have internal membranes.

The cells of protists, fungi, plants, and animals are eukaryotic cells, which are often about 10 times larger than prokaryotic cells and much more complex. Each eukaryotic cell has a nucleus, which contains the DNA in the form of chromosomes inside of a membrane; an internal membrane system involved in making large molecules inside the cell; and organelles such as chloroplasts and mitochondria. "Eukaryotic" refers to the nucleus (Greek for "true kernel"). The DNA molecules in the nucleus are associated with proteins called histones, and the membrane surrounding the nucleus has pores, which are not merely holes but are passageways controlled by proteins. These pores allow genetic instructions and materials, in the form of RNA, to go out into the cytoplasm and allow hormone messages to enter the nucleus. Part of the reason bacteria have rapid metabolism is that as soon as the genetic information of DNA is transcribed into RNA, the ribosomes start using the information to make proteins. In eukaryotic cells, the RNA must travel out to the cytoplasm first, a process that is slower but may allow a greater degree of control over the use of genetic information. . .

Free term papers are not written to satisfy your specific instructions. You can use our professional writing services to buy a custom written research paper, term paper, or essay on Science at affordable price. CustomTermPapers is the best solution for those who seek help in writing term papers, essays, and research papers related to Science and other relevant topics.