Prokaryotes Michelle Perez Andrea Carrasquero Period 3

-Prokaryotes are single-celled organisms and are roughly one micrometer in diameter. -Unlike Eukaryotes, prokaryotes do not have a nucleus that houses its genetic material. -One differentiating characteristic is that prokaryotes are asexual, meaning their offspring nearly always bear the exact characteristics of the parent cell. -Where a recombination of chromosomes occur to form unique entities (as with humans), evolution of the prokaryotic cell has been fairly stagnant over its two billion year lifespan.

A Prokaryotic cell is a cell that lacks membrane-bound nucleus. (Prokaryote is from the Greek meaning of Nuclei) Prokaryotic cells have few internal structures that are distinguishable under a microscope. Cells that are in the monera kingdom such as bacteria are prokaryotes.

-The small size of prokaryotes provides a high ratio of surface area to volume, making diffusion an adequate means for distributing nutrients throughout the cell. -Prokaryotic cells and fossils have been found in almost every conceivable environment on the earth, from hot sulfur springs to beneath the ocean floor and biomass within larger cells. Prokaryotes account for a significant portion of the past and present on earth. -A general prokaryotic cell can be considered to have three architectural regions, though not all the components are always present: - A cell envelope consisting of a capsule, a cell wall, and a cell membrane. -A cytoplasmic region that contains the cell genome (DNA), ribosome's, and various sorts of inclusions. -Appendages, sometimes present, called flagella and pili.

In a prokaryotic cell, most of the functions of organelles, such as mitochondria, chloroplasts, and the Golgi apparatus, are taken over by the prokaryotic cell membrane.

Similarities. Despite the difference the two cells have a lot in common. -They both perform the same kind of functions and in the same ways. Both cells are enclosed by a plasma-membrane and loaded with small structures called ribosome's. -Both have DNA which carries the archived instructions for operating the cell. The similarities are more than just visible and physiologically they are very similar in many ways.

Here's a visual comparison between a prokaryotic cell and a eukaryotic cell:

Differences. Despite the similarities, the differences are also clear. -The prokaryotic cell has a cell wall, and this animal cell does not. -Eukaryotic DNA is linear; prokaryotic DNA is circular. That means it has no ends. -Eukaryotic cells have a true nucleus, bound by a double membrane. Prokaryotic cells have no nucleus. -Both cell types have many, many ribosome's, but the ribosome's of the eukaryotic cells are larger and more complex than those of the prokaryotic cell. -The cytoplasm of eukaryotic cells is filled with a large, complex collection of organelles, many of them enclosed in their own membranes; the prokaryotic cell contains no membrane-bound organelles which are independent of the plasma membrane.

About the structure. Capsule – Is found in some bacterial cells, this additional outer covering protects the cell when it is engulfed by other organisms, assists in retaining moisture, and helps the cell adhere to surfaces and nutrients. Cell Wall – The outer covering of most cells that protects the bacterial cell and gives it shape. Cytoplasm – Is a gel-like substance composed mainly of water that also contains enzymes, salts, cell components, and various organic molecules. Cell Membrane or Plasma Membrane - Surrounds the cell's cytoplasm and regulates the flow of substances in and out of the cell. Pili – Are hair-like structures on the surface of the cell that attach to other bacterial cells. Shorter pili called fimbriae help bacteria attach to surfaces. Flagella - Long, whip-like protrusion that aids in cellular locomotion. Ribosomes - Cell structures responsible for protein production. Plasmids - Gene carrying, circular DNA structures that are not involved in reproduction. Nucleiod Region – An area of the cytoplasm that contains the single bacterial DNA molecule.