Chapter 1 Introduction to Biology

Hey everyone! Welcome to Biology 1406 biology for science majors chapter one let’s get started what is chapter one covering? Well what is biology? Biology is the scientific study of life. I’m gonna spend a lot of time in this chapter explaining this definition explaining what is a scientific study because it’s not a trivial thing to understand what science is and how to conduct a proper scientific study and then what is life which again is not a trivial thing life is actually quite difficult to define so we’re gonna get to this in a minute so let’s get started what is scientific study of life mean and what is biology? Science in general is knowledge about the universe and humans have been trying to gather knowledge about the universe for since time has began for humans and the way we’ve come about learning about the universe is through a process that we’ve developed as humans and that is the scientific method. A method of research with defined steps that include experiments and careful observation then there is like I said define steps we’re gonna go through and talk about those steps one by one so that you understand clearly what is science and how to conduct the scientific method. Okay, but before we do what you should realize is that science begins with observations and so because science begins with observations science much of it is purely descriptive you’re describing the universe you’re gathering truths and knowledge about the universe and then you’re gonna communicate those results to others. This here is the scientific method you see you start with an observation I said science begins with an observation from there you do some background research why would you want to do some background research well to know what’s known and what’s not known you don’t want to spend a bunch of time reinventing the wheel doing experiments other people have done so you might want to learn what is known what is not known about that field from there you could formulate a question for example why is Observation why is this thing going on what is this thing right and to answer your question okay this is the important part you formulated a question but to answer that question you’re going to make a hypothesis. Okay to answer the question you’re gonna make a hypothesis and the hypothesis is a suggested explanation for an event it’s it’s like an it’s like an answer that you came up with a possible answer that you came up with to answer your question now is it the right answer? I don’t know Is it the wrong answer? I don’t know you have to test it with an experiment so your hypothesis needs to be testable it can’t be something some explanation that you can’t test that would fall outside of the realm of science and it also needs to be falsifiable. What does that mean that means if you test it and it doesn’t turn out to be the right answer you need to be able to nullify the hypothesis you know throw out the hypothesis. Okay and hypotheses they actually allow you to make predictions so for example – if your hypothesis is “this is why this is going on” and you test it well then you should be able to predict what the outcome of those tests should be. Okay? So again science begins with an observation you do background research know what’s know and what’s not known you formulate a question “I wonder why that’s going on?” and then you formulate a hypothesis this is why that’s going on and – that’ll allow you to make a prediction which you can then test you have to be able to test if your hypothesis is the actual answer. Again, hypotheses allow you to make predictions those predictions you can test you can test the predictions I’m sorry you could test the predictions you can test those hypotheses using experiments okay experiments are what tests the hypothesis and there are parts of the experiment called variables variables are any part of an experiment that can vary or change during the experiment you want to have good controls and a good experiment. A control contains every feature of the experimental group except that is not given the manipulation that is hypothesized about. So, if you’re testing I don’t know, you’re testing a drug you want to make sure that the control group gets some kind of pill otherwise if you don’t swallow something you could be susceptible to what’s known as a for example a placebo effect where one group is given a pill one group isn’t and the group with the pill might feel better simply because they believe they’re being cured okay. So, once you’ve done your experiment you you gather data

and data are recorded observations there are two main forms of data qualitative data and quantitative data. Qualitative data is data that’s based on descriptions rather than measurements if you think of the famous researcher primate researcher Jane Goodall, a lot of her results were qualitative. For example if she’s studying a primate behavior she might note that on a particular day a particular primate was aggressive. On a different day it became docile, so those types of descriptions are not quantifiable right so they’re more descriptive that’s qualitative data Quantitative data is recorded measurements which have numerical values right you can organize them into tables graphs etc. Most data that you’ll encounter is usually quantitative So again, how does the scientific method work? You make an observation you can do some background research and to see what’s know and what’s not known formulate a question I wonder why that’s going on and then formulate some hypotheses to try to test test that question to see if it answers your question the the hypothesis is the answer to the question but then to test whether the hypothesis is the true answer to the question you need to: formulate experiments, collect data, draw conclusions okay and that will allow you to test whether or not you’ve answered your question. Arguably the most important part is down here at the bottom love communicate the results to others others must be able to repeat those experiments. I can’t stress how important this is that other people need to be able to repeat your experiments. Science, what you should realize as science students is science is not something where people need to take your word for something. Science is not something where someone who’s very intelligent had an idea and they proposed that and now you know that’s a new scientific theory. Ok? That’s not how science works science is not based on opinions or beliefs, science is based on hard data that is gathered through experimentation and presented to others so that they could repeat the same results it’s other people other scientists in the world in different countries cannot repeat your same results it’s actually not science That falls outside of the realm of science. So, if you’ve ever wondered why something is you know constitute science and something is considered outside of the realm of science, you just ask yourself can I do experiments and see results and can other people do the same experiments to see the same results? If not, it’s not technically science, it does not belong in the realm of science. So it’s good to understand so let’s look at the scientific method ok the scientific method we’ve been talking about let’s look at it with this lady and her conundrum. This lady is having an issue with a flashlight, this is there’s a most simple version of the scientific method you could think of. This lady is having an issue with her flashlight is just not working So, her observation is “my flashlight is not working” so she gets to thinking she could do some background research remember you could look and see what’s known about maybe flashlights not working. But, in this case it’s probably so straightforward her question is simply – “Why isn’t the flashlight working?” So, she has to formulate hypothesise right? Remember what the hypothesis is it’s a stated and answer to the question. The question is “Why isn’t the flashlight working?” So, what’s a good hypothesis? A good hypothesis again is the answer to this question why is the flashlight working hypothesis one well what if the batteries are dead the batteries are dead that’s a good hypothesis right can we test that yeah we can test it can we falsify that remember what falsify means that means if we test this hypothesis and it doesn’t work out we could rule out the hypothesis like eliminate the hypothesis. Yeah, we could falsify that. Here’s another hypothesis she came up with – “the bulb is burned out.” Okay, is that a good hypothesis? Yes because you could test it, sure, and you could falsify it you could rule that out if it’s not the bulb. So, let’s get started let’s look at what she does let’s look at the first hypothesis on the left. She’s testing for dead batteries okay the prediction would be what? Replacing the batteries will fix

the problem what did she do she pops out the old batteries she puts in fresh batteries she then tests the hypothesis and what lo and behold that did not solve her issue it did not fix the problem she put in fresh batteries and still nothing so she has effectively falsified the hypothesis. She has shown that the hypothesis is not true so she’s basically ruled out the dead battery hypothesis. Okay now that was an experiment right it’s changing out the batteries was the experiment. A good scientist would change one variable at a time and the variable being the batteries here so a good scientist if you in case you’re curious a good scientist would put the old batteries back in before testing hypotheses two but she may or may not have done that Because you don’t want to test multiple variables at the same time. She hops to hypothesis number two – “the light is burned out”. So, it’s a burned out bulb. So, the prediction here would be replacing the bulb will fix the problem. She does the experiment, she gets a fresh bulb she replaces the bulb with a fresh bulb on the flashlight she turns it on. Lo and behold it works great. So, what has she done here? Did she falsify the hypothesis? No. This is this is where it gets a little confusing. She failed to falsify the hypothesis. Which is actually what you want to end up doing. That shows that you’ve shown that the hypothesis in this case “burned out bulb” was the correct hypothesis, it answered your question and lo and behold you’ve solved your problem you’ve you’ve answered your question you’ve your observation is now that that the bulb was burned out and putting it a new bulb fix a problem and you’ve learned something about the universe Okay? So, again, why is it called “failing to falsify the hypothesis?” Let’s talk about that for a minute As a scientist, you want to be your own worst critic, right? You want to make sure that if you’re wrong you figure out you’re wrong before someone else does Scientists do not want to be wrong and so when you make a hypothesis which is a stated answer for a particular question, what you as a scientist if you’re a good scientist what you want to do is try to disprove yourself okay the best you can You really want to try to falsify your hypothesis you really really want to try to show that you that you’re wrong why because if if you despite your best efforts could not disprove that your hypothesis is wrong, then then it must be right! Right? Or, at least you have a good chance of that hypothesis really being the correct hypothesis. Again, what you want to do is actually answer the question, you don’t want to come up with your idea of what’s answering the question. You want to attack the hypothesis, you want to falsify the hypothesis. If you fail, well guess what? Good job! You failed to falsify the hypothesis, which means that the hypothesis really was the answer to your question. So that’s why it’s called “failing to falsify the hypothesis” Because what a good researcher is trying to do IS falsify the hypothesis if that makes any sense. So, let’s look at another example here of the scientific method Look here, this is the stream at Richland campus we’ve got a little stream we got a couple bridges right? Bridges that span the stream here, and if you’ve ever walked across these bridges on campus and looked down you’d notice things like turtles. And the turtles seem to be gathering right near the bridge right? Right near the bridge, you get this high concentration of turtles and then as you go further and further away from the bridge, you’ll notice that there are fewer into your turtles or less concentration of turtles less density of turtles so, wouldn’t that be an observation? Right? Wouldn’t that be an observation let’s go back to this (slide)… You’ve made an observation about the universe right? That the turtles in the stream, and they tend to gravitate or they seem to gravitate toward the bridges! Now what could you do at this point? It looks like you’ve started a scientific study you could do some background research. This will allow you to determine what other people have looked at or studied in this in this field if that question has already been answered You could formulate a question well what were your question be? What would your question be? Well.. how about “why are the turtles gathering near the bridge?” okay you might want to spend some time determining if

there really is a higher concentration of turtles by the bridge. But let’s say you do that and yes there are higher concentration of turtles by the bridge Well then you would say “why why are there so many turtles by the bridge?” There’s your question right there! Right? And then you from there you could formulate some hypotheses which can allow you to make predictions and make experiments! So let’s talk about that. So, think about this what are some hypotheses for the question – “why are turtles gathering near the bridges?”. Well how about how about – “because the students are feeding them”. Right? Think about that What’s happening all day long students cross and faculty cross and staff cross the bridge. Right? All day long. And have you ever noticed that students they they love the turtles and they they want to feed the turtles? They’ll throw you know some of their Subway sandwich or some of their bread or crackers or whatnot. They will throw down some little treats for the turtles. Well, that could that could possibly – you know – draw the turtles by the bridge so think about it. Is that a good hypothesis? Yes, because we get tested you know we could we could ask the students I don’t know maybe not to feed the turtles, we could ask them to feed extra there are multiple bridges maybe we could have you see how I’m making predictions right now? A good hypothesis allows you to make predictions it’s testable it’s falsifiable so the feeding hypothesis is actually a good one you know why because I could test it by let’s say on one bridge I tell students to feed. On another bridge I tell students not to feed. I could falsify it because if the feeding bridge and the non feeding bridge over time have no difference in the number of turtles by them, then it probably has nothing to do with the feeding – why the turtles are gathering. Right? So you see I’m making predictions. I could test it. I could falsify it that’s a good that’s a good hypothesis that’s a good hypothesis right there now again, we have multiple bridges and what you wouldn’t want to do for example is just on one bridge allow feeding and on the other bridge what you wouldn’t want to do is something like, I don’t know, block off the bridge so students can’t cross at all. You know why? Do you remember why? Because then you’d be testing two variables at the same time, right? So think about that. You’d be testing two variables at the same time. The students even crossing the bridge is a variable The students being present on the bridge is a variable. Feeding is another variable, you see that and when you tell students you can’t cross the bridge you’re actually stopping two variables you’re you’re manipulating two variables you you’re manipulating the variable of students on the bridge, and you’re manipulating the variable of feeding so there’s just an example of a ‘good experiment’, all right? Good experiments versus bad experiments: good experiments test one variable at a time, bad experiments test more than one variable at a time. So again, why would why would that matter well what if the turtles are just attracted to the sights and sounds and commotion of students? They’re curious about it, and that’s why they’re going near the bridge? Well in that case you know you’d mess up your results by manipulating more than one variable A good experiment we can set up on one bridge we could just leave it alone, or we could promote feeding we could tell students to feed we could actually tell them feed more on another bridge we could tell the students well you can cross the bridge but please feeding is prohibited and we can see well what happens with turtle concentrations over time we could measure it over a span of a week or two weeks or a month and see what happens Okay, well let’s say we do that experiment and there is no change in number of turtles by the feeding bridge and by the non feeding bridge Well, then what would we do? We now falsify the hypothesis which we which means we’ve defenestrated the hypothesis (we’ve thrown it out the window), and we can get started with a new hypothesis, right? We basically come up with another hypothesis and test that one. For example, what if it’s a hot day and you see under the bridge it’s all shady what if it what if the bridges are just providing shade and and the turtles are gathering near the bridges because of the shade? That’s another hypothesis. Is it a good one? Sure, we could test it for example we could put shade we could hang shade somewhere else we could hang up giant two-by-four and not 2×4 I’m sorry plywood a giant square piece of plywood somewhere else which provides a lot of shade and see if they

go toward that shade we could put heat lamps under the under the existing bridges make it uncomfortable and don’t provide any relief from the heat. I don’t know we could do a number of things that’s what I’m saying we could test that we could falsify that and let’s say we test it and that does affect the turtle population or turtle density? Well then we’ve failed to falsify the hypothesis that means shade really was the reason and the answer to our question and we can move on. So, that is a good scientific study and what you should realize though about science is that failing to falsify a hypothesis does not prove that hypothesis. You don’t really prove anything. And good scientists, by the way, rarely if ever use the word proved why because there’s always a chance that you’re wrong and there’s always a chance that do you’ve overlooked something so a good scientist would not say hey guess what I proved XY and Z, or I proved turtles are by the bridge because of I don’t know because of the shade. They would say “you know my data suggests that shade affects turtle migration turtle behavior turtle gathering” or “my results provides strong evidence for this”. They wouldn’t say things like “oh I proved this” because if you say something like you proved X Y & Z then you’re most likely gonna be wrong at some point and that doesn’t look right because a scientist is not trying to you know be wrong at a scientist is trying to show with evidence data and spend the data can never be a hundred percent, you know what I mean? So, for example let me give you an example let’s say this lady she changes out the bulb and she’s so excited she failed to falsify the hypothesis the flashlight worked great and she goes around telling her colleagues that guess what “I proved that my bulb was burned out!”. Okay remember, the hypothesis was burned out bulb right, she was so excited she says “my bulb was burned out”. Okay well what’s the problem with that? What if there’s someone in the audience that raises their hand and says “Um, excuse me but did you test the old bulb once you took it out of the the flashlight? did you actually, you know like attach it to another flashlight or did you test the filament with a with some kind of tester bulb tester?”. And what if she didn’t? Right? So her whole hypothesis was that the previous bulb was burned out, right? And what’s the one thing she didn’t do? She didn’t test whether the bulb was burned out! Do you see the problem there? Yeah now you look like a clown! You look like you don’t know what you’re doing. You look like someone who you know made statements that they didn’t really back up and and it would have been much better for her to say “well from what my studies from what I did my my evidence suggested that the previous bulb was burned out”. This way when someone raises their hand and says “oh but did you try this?” it’s like “oh I haven’t but the main thing I was trying to focus on was resolving the issue and not really testing the old bulb; however, we should have probably done that and thank you for your input maybe I’ll do that next time”. You see?That’s a lot better than saying “I proved the bulb was burned out!”. When you did everything but actually test that bulb. Okay? So anyway, I hope this makes it clear that good scientists rarely if ever use the word proved, instead they’ll say “we’ve shown strong evidence for” etc etc and then remember what was the last step of the scientific method? Communicate your results to others well this is called reporting scientific work. There are these journals you can think of them as magazines called scientific magazines and in them you publish scientific studies. You may have heard of journals called ‘Science’, the journal ‘Nature’ the journal ‘Cell’. These are very prestigious journals where scientists at you know they they submit their findings. The good part about these journals is they don’t just take your word for it like – “oh, hey Dr. Jones, or Dr. Smith, we know you’re a famous scientists we’re just gonna take your word for everything and we’re just gonna publish it right away!”. No, what these journals do is they send those results they send those manuscripts the manuscripts are that typed up results with all of the the abstract which is basically a concise summary the introduction which as a background a background to the field materials and methods so other scientists can can

reproduce your results results what were your results and a discussion of those results right this whole thing is called a manuscript. The manuscript that you submit to a journal, the journal staff sends your manuscript to other scientists in the field, right? There could be a scientists in Australia, there could be two scientists in America, there could be a scientists in… I don’t know China and all of these different scientists will sit down, read your manuscript let’s say our turtle study manuscript. They’ll read your manuscript and they will determine whether it has merit like did you do good experiments? Did you have good experimental setup? Did you did you test all of your variables? Did you test only one variable at a time? Did you do good statistics? Did you did you count enough turtles or if there were only two turtles in the whole stream, that’s not a good study you need dozens of turtles right at least! So, was it a good study and if it wasn’t a good study they could suggest revisions they could say you know Dr. D you should really try doing this experiment with more turtles so you should go somewhere where there are more turtles two turtles is not enough to do this experiment so come back when you’ve looked at… I don’t know a hundred turtles Well then I would get that feedback from the journal the journal would say “Hey Dr. D that was a good study; however, your peers have suggested the following revisions. Please make the following revisions and then so that makes my my science stronger. I need to go back I need to do a better study and then once I’ve done that I could resubmit and hopefully the peers would be satisfied and they will publish my manuscript in the journal and then I could get some notoriety for that and I could contribute to knowledge and contribute to science that way That’s what peer review means and it’s how science works and and guess what I’m not done! At that point even if this even if they were able to publish my manuscript I’m not done, other scientists need to be able to look at my materials and methods and those scientists you need to be able to redo those experiments and recapitulate my results – they need to be able to reproduce my results and if they can’t reproduce my results and see the same thing when they do the shade difference and they see the turtles migrating the way I saw it well then pretty soon people will realize that my results aren’t very trustworthy and that I don’t do good science and then I’m ridiculed out of the field I am you know people understand that my science isn’t very good. So you can’t just put any old stuff out there if you’re a scientist you need to, again, you’re the one who is attacking your own hypothesis and trying to falsify your own hypothesis the most And you’re the one trying to just disprove yourself okay you can’t prove anything but you can disprove stuff all day long. All right so that’s how science works and so what have we done so far let me flip to the beginning real quick Again, what was biology? Biology was the scientific study of life. Okay, we have just discussed what is a scientific study okay now we’re gonna discuss what is life so I’m gonna take a brief break here and you could take a break – hit the pause button, and maybe go to a restroom, grab a drink or stretch your legs. And I’ll explain what is life Hey everyone welcome back! Hope you had a nice little break there. One slide that I wanted to get to before we start talking about life is this one here it covers a Theories. Scientific theories what you need to understand about science is a theory is a tested and confirmed, a tested and confirmed, explanation for observations or phenomena. What this means is that there’s a huge body of interconnected evidence with huge number of manuscripts published in reputable journals that supports each different theory so a theory is something that’s all but proven, ok compare that to the general meaning of theory. The general meaning of theory means it’s like a guess. It’s like if your slippers go missing… “I have a theory my dog took it!” That’s what theory means to you know in general in layman’s terms but in to a scientist remember when I said a scientist will not use the word ‘proved’?

Well, the closest you can get a scientist to saying they’ve proven something is they say it’s a ‘theory’ ok so just be aware there are the Big Bang Theory, the Theory of Evolution, General Relativity Theory, the Cell Theory, all of these are theories all of these are theories! Gravity is a Theory! All right? So, a Theory is tested and confirmed and there is no significant supporting evidence to the contrary. Ok so just be aware of that theory to a scientist means a whole different thing than a theory to someone just in everyday life ok so that being said we’re moving on to – ‘What is life?’, remember Biology is the scientific study of life so what is life life unfortunately for us it defies a simple explanation there’s no really super easy definition there’s creatures on earth that some scientists would would argue are alive other scientists are you are not alive so there it’s not so clear-cut and well-defined so what scientists agree on is that there are certain characteristics of life these are the characteristics order sensitivity or responding to environment reproduction adaptation growth development regulation ‘homeostasis ‘- which is a fancy way of saying being able to maintain internal conditions ideal internal conditions energy processing the ability to evolve these are the things these are the characteristics of life and if you’re a living thing typically you possess most, if not all of these characteristics so humans possess all of these characteristics some living things that do not possess each and every characteristic, but they’ll possess most of them okay so as long as you possess most of these characteristics you can be considered a living entity okay so that’s I guess the best definition of life now when you’re studying biology you’re obviously studying organisms right you know the organism is at this level here an organism is a creature you and I are the human organism right and you can break that down into simple or simpler levels or you could go up into more and more complex levels so just just to give you an idea we are an organism but you could break us up into our different organ systems for example we have you know the nervous system the cardiovascular system the immune system and each one of those has different organs which are involved with which include tissues tissues or parts of the organs these tissues are made up of individual cells in fact in fact if you’re not a multicellular organism like a human if you’re for example a single-cell organism like a bacteria well then you don’t you don’t actually possess tissues organs organ systems or anything like that you are a cell and that’s it one cell big however we are you know we are multicellular organisms so our cells make up our tissues our tissues make up our our against makeup our organ systems and those organ systems together make us up which is the organism and of course cells are made up of organelles if you’re wondering what is an organelle organelles you can think of them as functional parts of the cell okay organelles are functional parts of the cell so what do I mean have you heard of the nucleus okay that’s a part of the cell have you heard of the mitochondria? Right, that’s a part of the cell. Have you heard of ribosomes? That’s an organelle, a part of the cell so if you haven’t heard of those things don’t worry about it but just be aware that just like us organisms are made up of organs and organ systems cells are made up of organelles functional parts of the cell and those organelles of course are made up of molecules which are made up of the atoms which are essentially the elements we’re going to be talking all about that chapter 2 and chapter 3 okay now that gives rise to the organism but we could go in more and more broad here a group of the same species of organism is called the population so for example at Richland campus you would have the human population you could have the turtle population fire ant population the I don’t know crepe myrtle tree population populations are groups of the same species in an area okay so that’s what you need to be aware of what is a community a community to a biologist a community means all of the different species in an area so on Richland you have the population the human population the turtle population right all those populations together make up the

community so for example the Richland community would be: all the humans all of the turtles all of the ants all of the trees and bushes and fish and all of the birds etc and grasses and bushes and all that so what’s the ecosystem you can think of ecosystem as community plus environment now you’re not just talking about the community which is all the different creatures on Richland campus you’re talking about the dirt the air you’re talking about the stream you know all of that that’s the ecosystem and of course all the ecosystems put together make up the biosphere. Bio means life and sphere meaning it’s a big circle so that we’re talking about the big circle of the Earth right the entire planet is the biosphere it’s made up of ecosystems which are made up of communities which are made up of populations you get the point all right so like I said there are different organisms on the on the planet different species so what is a species a species is a group of organisms if you talk about multicellular species it’s a group of organisms that can interbreed and have fertile offspring okay so for example our species is called sapiens that’s our species homo is our genus genus means even another group of closely related organisms so homo is our genus it’s a group of closely related organisms sapiens is our species it is the population it is the group of organisms that can interbreed and have fertile offspring what do I mean by fertile offspring? So, for example when humans breed they have offspring that can then have more humans right but let’s say members of a different species in the genus a different species let’s say a horse and a donkey breed they can actually breed, a horse can breed with a donkey however their offspring is not fertile it’s called a mule the offspring is called a mule and a mule is not fertile you cannot have more mules right same with a lion and a tiger they make ligers ligers are not fertile they are not fertile offspring okay that’s why they are different species they are not the same species okay and this this this two-word epithet where you got genus and species this is called binomial nomenclature here it was derived by or brought to you by Carl Linnaeus in Swedish botanist 18th century and there’s a very specific way of writing this binomial nomenclature the first word is again the genus the second word is the species the first word notice that it’s capitalized in this case capital H the second word has to be lowercase all right so it’s very important capital lowercase and then the whole thing needs to be either underlined or italicized does that make sense the whole thing is either underlined or italicized for it to be correct binomial nomenclature okay so that’s that’s that’s binomial nomenclature and the study of how organisms are related to one another this is the study of taxonomy so a taxonomist is someone who studies different organisms on the planet and studies how closely related they are puts them into species puts them into genus and then order and all the other classifications let me let me talk to you about that actually let me talk to you about that here a taxonomist what takes a creature such as the black bear okay this is Ursus americanus the black bear and the black bear is a species americanus but it is in the genus Ursus notice Ursus is capitalized Ursus would be all the other bears right so you’ve got the black bear and then different species of bear you’ve got the polar bear and you’ve got the brown bear the grizzly bear and they’re all in the genus Ursus but they are of different species okay then you have different layers you have even more layers and they get more and more broad more and more less less and less general I’m sorry more and more general you should I should say you’ve got family which includes in this case a lemur like creature you’ve got order which includes in this case that all of the carnivores you’ve got class which includes all the mammals you’ve got phylum notice how we’re getting more and more broad more and more broad a phylum which includes all of the chordata, chordata means you’ve got a backbone you’ve got Kingdom which includes all of the animals you’ve got domain and the domain is Eukarya

so I’m gonna tell you what Eukarya is in a little bit okay but again a taxonomist would say okay here’s a new species of black bear for example where does it fall into one Kingdom and what phylum in what class and so it’s good to understand this whole taxonomic hierarchy this is called the taxonomic hierarchy from species all the way to domain okay in fact you may want to memorize this domain kingdom phylum class order family genus species and I’ve got a nice little video here you can click on bottom left which will help you to memorize this I’ve got a nice little mnemonic device for it you may want to watch this video here okay so that’s taxonomy. Let’s go back and talk about the different types of cells there are two types of cells that you need to know about there are eukaryotic cells these are cells that have membrane bound organelles the main membrane-bound organelle is the nucleus and then you got prokaryotic cells which are simpler cells they do not have a membrane bound organelles and they do not have a nucleus so again all cells have a membrane around the cell that’s called the plasma membrane okay again you should understand that all cells have a membrane around the cell that’s called the plasma membrane all right the difference between eukaryotic cells and prokaryotic cells the main difference is that despite the fact that all cells have this plasma membrane eukaryotic cells have more organelles inside which have membranes whereas prokaryotes do not have organelles inside the cell that have membranes they have organelles don’t get me wrong they just don’t have membrane bound organelles okay so the eukaryotic cells have a nucleus that’s the main membrane-bound organelle but they also have for example they have mitochondria which is another membrane-bound organelle plants have chloroplasts which is another membrane-bound organelle you can have endoplasmic reticulum which is another membrane bound or you don’t need to know about these structures now but I’m just listing off some the Golgi apparatus is another membrane-bound organelle none of the prokaryotic cells have these things prokaryotic cells have non membrane bound organelles for example the ribosomes right ribosome turned on membrane bound organelles okay so you and I we are eukaryotes what does that mean our cells you know we have made up of billions of cells right our cells are eukaryotic cells if you were to crack open one of our skin cells for example you would see inside a bunch of membrane bound organelles and of course again what’s the main membrane-bound organelle the nucleus right but a prokaryotic cell or a prokaryote for example E.coli or salmonella these guys don’t have a nucleus inside so if you crack that E.coli open you wouldn’t find a nucleus inside or any other membrane-bound organelles okay so here’s an example of a eukaryotic cell okay this would be for example your cell and here’s an example up here at the top right of a prokaryotic cell okay notice the eukaryotic cell has all these big structures inside these are membrane bound organelles and you see the big blue one in the middle that’s the nucleus okay the prokaryotic cell notice how it doesn’t have membrane bound organelles inside now here’s something you need to understand okay let’s take a minute to think about this okay it’s actually kind of important to understand I said all cells have a membrane around the whole cell that’s got the plasma membrane but only the eukaryotic cells have a membrane bound organelles inside including the nucleus so what’s this blue stuff in here look at the look at the prokaryotic cell what’s this blue stuff in there okay so what you need to understand is all cells have DNA inside right so our DNA is inside of our cells right so what’s the difference between a nucleus and not? okay in eukaryotes like you and me our cells like our skin cell has DNA but that DNA is in side of a membrane okay does that make sense our DNA is all in our chromosomes are inside of this membrane it’s actually a double membrane we’ll get into that later but that that’s what the nucleus is it means that your DNA is inside of a membrame okay that’s nucleus the E.coli look at the E.coli here at the top right for example let’s pretend this is E.coli it also has DNA the blue stuffs DNA it’s it’s chromosome okay it has DNA okay but

its DNA is just floating around in the cell all right if the DNA is not inside of a membrane so that’s why we don’t call it a nucleus you see here the the DNA is just floating around the cell so the DNA is not in a nucleus in this case you would call it a nucleoid nucleoid all right now uh again eukaryotes have the DNA inside of a nucleus prokaryotes have the DNA floating around in the cell by the way you see this fluid inside of the cell just this fluid inside of the cell that’s called the cytoplasm or cytosol all right in the eukaryotes our DNA is inside of a nucleus inside of a membrane and so the DNA is not in the cytoplasm is it it’s inside of the nucleus in a prokaryote however look what’s look what’s going on the DNA is floating around in the cytoplasm okay so good to understand all right so now we know there are two types of cells there are eukaryotic cells and prokaryotic cells what you need to now understand is that there are three major groups of life all right look bacteria archaea and Eukarya these are the three major groups of life and all living things all living creatures fall under this group bacteria this group archaea or this group Eukarya all right two of these groups are prokaryotic bacteria and archaea these creatures are prokaryotic creatures and they are single-cell creatures this group Eukarya to which we belong by the way you and I belong to this group Eukarya these are all of the creatures that are made up of eukaryotic cells okay and you and I are a multicellular creature right we are humans but you should understand that there are some Eukarya that are single-cell have you ever heard of for example amoeba or protozoa or Paramecium these are single-cell Eukarya so eukaryote can be single-cell creatures they could be multi cell creatures however archaea and bacteria which are prokaryotic these two major groups of life these are single-celled creatures okay now here’s the thing these groups have names they’re called domains okay there’s the domain bacteria the domain Archaea and the domain Eukarya so let me show you do you remember this you got the black bear and look what domain it belongs to remember there are three domains of life the black bear belongs to Eukarya where would we belong which domain we would also be in eukaryote okay does that make sense we are also in Eukarya all right so there are three domains of life Eukarya archaea bacteria again the domains bacteria and archaea they’re composed of single-cell creatures okay and eukaryotes can be single or multicellular in fact the Eukarya you may be familiar with they include the plants the fungi animals and also creatures called protists you know what protests are protists a lot of them are single-celled creatures these are the ones I was telling you about these are the protozoa these are the ones that are Paramecium are Trypanosoma amoeba these are a lot of these are single-celled eukaryotes not all of them but a lot of them are algae and things like that fall under protists okay so you can see plants animals fungi protists these are all types of Eukaryotes and that’s it that actually wraps up this chapter the last the last last concept here is is you should know again remember there are three domains bacteria archaea and Eukarya remember these are the three major domains of life and all living things fall under one of these three domains and what you should realize is bacteria are prokaryotic archaea are prokaryotic Eukarya are eukaryotic however look at this okay this is what you need to understand look at this this is I’m sorry this is called the phylogenetic tree this is the tree of life okay and how it shows you how closely different organisms are related to one another notice this there’s a common ancestor here in history there’s a common ancestor and that common ancestor branches off two directions one becomes bacteria the other becomes the Archaea and the eukaryotes this means do you know what this means this is actually kind of interesting if you think about it what this suggests is that Eukarya which includes you and me and archaea which are these creatures that are

prokaryotes that usually live in extreme environments even though archaea and Eukarya you know are really different once prokaryotic once eukaryotic we share a more common ancestor than archaea does to bacteria okay again what does that mean in layman’s terms that means that archaea are more closely related to us Eukarya than they are to other bacteria to two other prokaryotes called bacteria so these prokaryotes are more closely related to us than they are to bacteria which is really fascinating to think about we have a more common ancestor with archaea than bacteria do okay so that wraps up chapter 1 again welcome to biology 1406 I hope this is a good semester for you I’ve got these videos here by the way you see whenever in the in the notes whenever you see this at the bottom left you see dr. D click me you can click that icon and you’ll get a another video that will help you to understand the concepts better so go ahead and click on those and you’ll get many videos that you can watch to help clarify some of these points okay I’ll try to put these in you know it increase the number of these as I can and make more videos as I can okay thank you very much for watching and tune in next time