1. Overview of Cell Biology
Prokaryotic Cell Architecture
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Hi in this video we are going to be talking about Procure IAT ICC cell architecture. So first a lot of text behind me but it's a really simple concept that I'm gonna be talking about over the next few minutes. And that is that pro carry out ICC cells are diverse and that's really it. They're just extremely diverse. But let me talk about some ways that they are diverse. Um So first is that they're classified in these two overarching domains. You've heard these before? RKO bacteria sometimes arcadia can be just termed RKO bacteria, bacteria can also be called and seeing you bacteria but essentially it all means the same thing and they're all pair of areas. Now they come in all different shapes and sizes but all of them are single celled organisms. You can kind of think or at least I do I think single celled organism. Super simple. But that's not true actually. They do all of these different diverse processes which I'm going to talk about a little bit now. But they also can actually form these social groups like films for instance or chains. So for instance the film on your teeth when you don't brush it, that's actually some bacterias and precarious working together in these social groups that form those films and they can come in all different types of shapes spherical, rod shaped, spiral. So they're very diverse in cell type in size. Now traditionally we actually didn't think they were that diverse. So um some traditional techniques which include growing them in laboratories. Um only identified around 6000 species which is relatively small, but we now know that this represents less than 1/10 of 1% of all the pro periodic species, it's so tiny, such a tiny amount. Um So how did we find them if all this diversity if we couldn't grow them traditionally in a laboratory? So we sequence the meta genome. So what does it matter genome? Well, that is actually the collective genome of a species and a habitat scroll up a little. And so what that means is if I were to collect the meta genome of a certain environment, I would go to that environment, say hydrothermal vents and I would collect the water and then I would just DNA sequences. And because all of that water in there and contain so many different organisms, I would get all the genomic sequences of the organisms that live in that habitat and not just a particular one. And so when I get the sequences back, I have the collective genome of the species in a certain environment or habitat. And then I can say, okay, this is really diverse. This represents so many different thousands of organisms. Um And that allowed us to really identify the pro carry on diversity. So because there's this huge diversity, thousands upon thousands of pro chaotic species, they have diverse metabolism pathways. We've talked about some of these that they can be photosynthetic be aerobic, which is require oxygen. Anaerobic don't require oxygen. Um And the reason that they're so diverse are more diverse than eukaryotes is because they rapidly divide. And so if you're rapidly dividing rapidly producing more offspring, you're rapidly evolving that allows for more diversity. Now, one way that you may have heard members of the Arcadia domain um called is this word called extremophiles and pretty much the reason they're called that is because they tend to live in harsh environments. They tend to live near volcanoes or deep in the ocean or really cold antarctic areas. Um And so that also contributes to the diversity because they're not restricted to one environment, they can literally live anywhere in the world, bro, carry outs can. So I just wanted to show you this example. This is not nearly all of the shapes and sizes and groups that pro carry outs can form. But you can see here just by looking at it, there's a lot of diversity just in these few organisms I'm presenting, you can see that there's the circle organisms, there's these long stringy ones, they can form social groups. Um essentially they're just all very diverse. Um So now let's move on to the next concept
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So we know pro chorionic cells are diverse but what are some of the structural common features between them? So pro periodic cells have specific structural features that define them. So one of the biggest ones is the lack of a nucleus and that's actually in their name. So pro means before carry outs mean kernel or nucleus. So pro pro literally means before nucleus. So they do not have a nucleus. But what they do have is they all contain a plasma membrane and most of them contain also a cell wall. So um they don't contain a nucleus. They do contain plasma membranes but they also for the most part don't contain internal membranes. These are things like organelles, mitochondria chloroplasts that you remember back from your um intro bio class. Now there is one exception to this. This is called cyanobacteria. So cyanobacteria actually contain in these really complex internal membranes where they perform photosynthesis. Now that's the one exception. The rest of the pro chaotic cells do not have internal membranes um but they have to be able to support themselves. So they do have these primitive side of skeleton elements. Remember back to intro bio sido skeleton really performance the structure of the cell and they can move um which we kind of know this just through, you know, looking at pond water or blood or any kind of the labs that we've done with cells is that they actually do have the ability to move. Um And one of the main ways that they do this is through a structure called the Mandela. So let's look at a pro periodic sell. So you see here that there is no main nucleus. There's this thing called a nuclear oil, which we'll talk about, but that's pretty much just where they store their DNA. But this is not a nucleus. They have a flagellum here. They contain a cell wall, a cell membrane and but generally they're very fairly simple. If you remember back to looking at different cells and your early bio classes, probiotics are fairly simple. So now let's move on to the next concept.
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in this video we're gonna be talking about pro carry attic genetic features. So this has to do with DNA storage structure and replication. So um how appropriate excel stores. Um it's D. N. A. And how it replicates it are distinguishing features of of pro cryonics cells. So remember back I said pro chaotic cells do not have a nucleus but they do have a structure called a nuclear oid. Which is just where they keep their D. N. A. And it's actually a circular chromosome. And that's where their DNA is packaged. And so A D. N. A. Is not contained inside in inside contained in any kind of intracellular compartments no nucleus. And they don't have nuclear envelopes. They also don't have nucleus nuclei plural for that. And then um because they don't have these specialized compartments to hold their D. N. A. Um they actually don't have that much DNA. So they have about eight million base pairs for an average pro cryonics l amounts around 5000 proteins. Um Now if we think of this to a human cell for instance that's so small. Human cells contain upwards of 25,000 proteins and that's only 2% of the genome. It's a huge amount of genetic material and eukaryotes but a small amount in pro carrots now um that's how DNA is stored, what it's how it's structured but how is it replicated? So pro chaotic cells undergo binary vision and a complete copy of the D. N. A. Has passed on to the daughter cell. So genetic information can also be self through organisms through conjugation. Which is a different process. So let me go down here and talk about this. So binary fission is where DNA replication occurs. And you see you get two copies of the entire D. N. A. And that split. And then that goes into the daughter cells where each cell contains a single copy. So that's binary vision. Now that's um file replication. There's this thing called conjugation. Um And that's just genetic sharing between organisms. But that's not dividing. That's actually just giving some genetic material between organisms. So we talked about DNA storage structure and replication. Let's talk about DNA transcription and that's the process of turning A. D. N. A. Into an R. N. A. And then eventually into a protein. So expressing that gene and DNA transcription and gene expression in pro carry optics cells is very simple. So we're running into a theme here where DNA is stored in the simple nuclear oid um D. N. A. Or the pro chaotic cells divide through binary fission. And the simple process DNA transcription is also simple. All happens in a single compartment. It really requires very little processing. Um And it does use rival For translation. Which if you remember back to your bio 101 sort of throwing these terms out here just to review. It uses ribosomes for translation but they are smaller and less complex. And the ones you're familiar with from your intro bio class for eukaryotic cells. So for pro cryonics cells and their genetic storage, it just think simple, it's more simple. So with that let's move on to the next concept.
Which of the follow is true about prokaryotic cells?
They have a plasma membrane, nucleoid, and nucleus
They have a plasma membrane, nucleoid, and no nucleus
They have a plasma membrane, and reproduce slowly
They have a plasma membrane, reproduce slowly, and divide through binary fission
In prokaryotic cells, where is the DNA stored?
Prokaryotic cells always live alone, and never form social groups.