M.Ed., Stanford University
赢得多个教学奖励
Patrick has been teaching AP Biology for 14 years and is the winner of multiple teaching awards.
Prokaryotic cellsare much simpler than eukaryotic cells. Prokaryotes don't have many membrane bound internal structures such as organelles or nuclei. Their genetic information floats freely within the cell in circular loops called plasmids. Cellular processes within prokaryotes are much simpler because of the lack of organelles.
Prokaryotic cells are one of the most basic kinds of cells that are out there in Biology. They are the cells of bacteria, so let's take a look at what makes up the key characteristics of a prokaryote.
Now their name tells you one of their most important things; pro means before kary means nucleus, so this tells you that this is what cells that evolved before the nucleus came about look like, so they do not possess internal organelles inside their cells that have double membranes around them like the nucleus or the mitochondria or the chloroplast. Similarly unlike Eukaryotes they only have one chlorop- one chromosome in them and it's actually a circular molecule now it's called “naked†not because it's going around there flashing the other organelles. It is because it's because it does not have a lot of proteins wrapped around it to help organize it, since they only have a little bit of DNA compared to a Eukaryotes so there's no need for that kind of organization.
Lastly they have their own special kind of ribosomes that are different from the Eukaryotic star ribosomes that your cells have or plant cells or fungi, so let's take a look at the structure of a Prokaryotic or bacterial cell.
Now these labels here are little bit small for you to see but they give you the right basic idea. This is a kind of bacteria here and you could see here is the DNA all kind of floating around inside the cytoplasm of the cell. Now they will have a cell membrane but that is often wrapped in an external wall sometimes called a capsule or a cell wall. Now this can be made out of various many various kinds of materials whether it's bacteria glycen or sorry bacteria peptide or glycen or other kind of molecules. You'll see the ribosomes those are the small little things floating around and then they may have a few other small organelles like some small little vacuoles or vesicles but that's pretty much it, the one thing that is a little bit different on the outside is they have flagella much like our cells do but our cells do this kind of motion called undulation. Bacterial cells their fungi rotate like a bored motor to make them go and that's a Prokaryotic cell.
