Taxonomy

in this video, we're gonna recap the classification categories of life. And so taxonomy is the name of the branch of science that classifies, identifies and properly names all living organisms. And there are actually eight biological classification categories used to identify all life. And you guys have talked about these categories and your previous bio courses. So we're just gonna do a quick review here. And in our example, we have a vertical representation and a horizontal representation of the eight categories. And to refresh your memories, these eight categories include domain kingdom, phylum, class, order, family, genus and species, and in parentheses. We have the plural version of these categories and notice that domain at the very top has the largest broadest bar, which means it is the most inclusive and all living organisms fall under it. Now, as you move down in categories, the bars get smaller, which means the categories get less and less inclusive and less organisms fall under it until you get to the least inclusive category species which Onley includes one type of organism. And so you could see that over here on the right, where domain is the most inclusive category and species is the least inclusive category. And there's an acronym to help you guys remember the categories in order from Most inclusive, toe least inclusive. And that acronym is Dear King Philip came over four great soup. And so we have an image of King Philip here and the delicious looking soup that he came over for. So if you can remember that, dear King Philip came over for great soup, you can remember the order of these categories from most inclusive, toe least inclusive. And so, in our next video, what we're gonna do is talk about a particular category, the domains of life. So I'll see you guys in that video.

so we already know from our previous bio courses that there are three domains of life. Bacteria. Archaea and you, Correa and bacteria and archaea are grouped together as single celled, pro carry ah, tick organisms. And that's because they lack a membrane bound nucleus. And bacteria are theorized to most closely resemble the very first cells because there are less divergences in the evolutionary tree, which is built by comparing the DNA sequences of many different organisms. Now, Archaea include organisms such as halo files and thermal files, which live under intense conditions. Halo files live under high salt conditions, whereas thermal files live under high temperature conditions. Now we already learned that you carry a our cells that contain a membrane bound nucleus, and this includes all multi cellular organisms as well as the single celled protests. Now, in our example below, we have an evolutionary tree and noticed that on our timescale over here on the far right on the present, we have the three domains of life which represent all living organisms today and notice that each of these nodes in the evolutionary tree represents a divergence in the tree of life and going back in time bacteria encounter less divergences than archaea, and you carry a dio. And so for that reason, bacteria are theorized to most closely resemble the very first cells and bacteria and archaea. They're grouped together as single cell pro carry attic organisms, which lack a membrane bound nucleus whereas you carry a include the eukaryotic organisms that do have a membrane bound nucleus. And so humans and ostriches are both multi cellular organisms. So they both fall under the you carry a domain and notice that when we compare the biological classifications, we see that up until class, humans and ostriches are exactly the same. And then once they reach class, they start to fall under different categories of life. Now, in our biochemistry class, we're gonna be mainly focusing on eukaryotic organisms. However, recall from our previous videos that the biochemical unity of life states that all living organisms have a resemblance at the biochemical level. And so things that we learn about eukaryotic organisms are gonna also be able to apply to pro carry attic organisms. And so, in our next video, what we're gonna do is directly compare pro carry attic organisms with eukaryotic organisms. And I'll see you guys in that video

So, as you guys already know, pro carry attic and eukaryotic cells are the broadest and the most distinct groupings of all life, so it's important to be able to compare and contrast. And so, in our example below, we have a Venn diagram where on the left we have pro carry attic sells the right. We have eukaryotic cells, and in the middle we have characteristics of both. And so we're actually going to start with the characteristics of both. And so both pro carry attic and eukaryotic cells contain cell membranes and recall that all cells have cell membranes. They both also have structures known as ribosomes, which will do a refresher on in some of our leader videos. And they display all eight characteristics of life and contain all four major macro molecules that we talked about in our previous videos. And those are proteins, nucleic acids, carbohydrates and lipids, and so the contrast pro carry attic and eukaryotic cells. We already know that pro carry attic cells do not have a nucleus, whereas eukaryotic cells contain a nucleus. Now, pro carry attic cells tend to be smaller, less complex and Onley uni cellular organisms and their diameters. Onley range from one to about five micrometers Now, in comparison, eukaryotic cells are larger mawr complex, and they could be either uni, cellular or multi cellular, and their diameters range from 10 to about 100 micrometers. So eukaryotic cells are double the size all the way up to times the size of a pro carry attic sell. So that's much, much larger. And so, as you guys already know, you pro carry attic cells tend tohave circular DNA, and they do not contain membrane bound organelles, whereas eukaryotic cells have linear DNA and they do contain membrane bound organelles. Pro carry attic cells divide by a process known as binary fission, whereas eukaryotic cells divide by a process known as That's right, my toe sis. Yeah, and so although both pro carry attic cells and eukaryotic cells contain ribosomes, their ribosomes differ from one another, and eukaryotic cells have larger 80 s ribosomes, whereas pro carry attic cells have smaller 70 s ribosomes, and we'll talk more about that in some of our later videos. Now there are a lot more similarities and differences between pro carry attic and eukaryotic cells. However, this is a good summary that I want you guys to know as we move forward in our course. And so this concludes our comparing contrast and I'll see you guys in the practice videos.