cell division a little bit more but more specifically looking at asexual and sexual reproduction some of the times people ask you know humans don't do asexual reproduction well do they they kind of um you kind of have to think out of the box like we have certain prescribed ideas when we think about reproduction we might be thinking about making new individuals right well that's what's happening here this is with a prokaryote like bacteria or archaeans and what they have in their situation uh for their chromosome they have a single chromosome that they then just double up and then once they double that up they can split them into the two different cells here and then now we have two cells so we've made new individuals that's asexual reproduction right making two new cells that kind is called binary fission and if you recall there are also two of our organelles that have their own dna and they're uh originally likely from prokaryotes do you remember what those are hopefully you remember there's mitochondria and chloroplasts so they go through this binary fission when they are going to make more chloroplasts like in g1 or if they're going to make more mitochondria like a g1 there's asexual reproduction also they'll refer to it as binary fission also in some protists and that's just because their chromosomes are a little bit different but basically they're splitting into two now there's other kinds of interesting kinds of reproduction one's called parthenogenesis so here's an example of an aphid an aphid is kind of like the mosquito of the plant world they stick their little mouthpiece into the sugar part so that's the phloem um of the plant and then suck that out right so kind of like us with our blood but instead they're doing this with plants well during certain times of year they go through and have sexual reproduction and then at other times of year the females might suddenly produce an entire young on her own so she hasn't combined her genetic material with another individual so that's definitely an asexual reproduction so this is basically a clone right another example would be looking at carpenter bees or crayfish they can do this very surprising it was also surprising to find that there would be a shark in a tank and she had been by herself for the entire time and then suddenly later on there were two sharks so that has been found as well that's um this parthenogenesis as well and um also this has been known to happen within komodo dragons so the idea is that for parthenogenesis you have the development of a new individual from an unfertilized egg and that can happen so that is a sexual reproduction because it has a genetic material of only one individual and of course you know mitosis in mitosis what we have here is growth that will occur um replacement of cells we've talked about this and also repair so all these are examples so again do humans do asexual reproduction yeah we produce new cells uh do we produce new individuals this way no so you have to kind of think about that a little bit wider in kind of a different way than we normally think about this right it's kind of crazy so here's some examples of mitosis happening in animal cells so here's hydra this is that really small little um organism that's related to anemones that or jellyfish that have tentacles that have stinging cells right that's what this is and what they do is they form these little um buds on the sides of their body and then those grow and grow through mitosis and grow through mitosis and then at some point they're mature and they just pinch off now i don't know about you ladies but sounds like a much easier way than what we have to do in any case um i don't know how attractive that would be if a new individual growing on your side but they grow inside of you i don't know yeah so there are also sea stars that can grow from a broken arm which is unusual most of them you have say an arm breaks off and it can replace that arm but there's a few um species one genus in particular that from an arm that's been broken off they can regenerate all the rest of the arms which is really funny because you know they have five arms typically but in this particular species when it's been regrown from another arm they usually end up getting six so it looks really strange um and then of course if we're producing more skin or if we're producing red blood cells or any blood cells for that matter in the bone marrow that's mitosis so here's some examples also of mitosis you've got a spider plant it sends out a runner here this is the little plantlet that forms and then it can be either cut or it just dries up and then it forms a new plant and that's asexual reproduction just completely um individual right um here is a maternity plant which produces little plantlets on the edge of its leaves really strange they plop off on the side and they become a whole new plant you can see why she calls or people call this a maternity plant um or if you see um plants with bulbs or corms they'll form a new piece on the side like in garlic and that clove will come off and that will be a new plant and people do that all the time they'll take their tulips and separate them and then make tube tube chill plants here's an example of like crab grass where if you've ever had a lawn and then you pull out one of the crabgrass plants because it looks different and then you start pulling it out and pulling it out and you realize you're going across the entire yard that's because it's all one plant that has been attached by rhizomes very efficient way of just taking over right this strawberry plant is doing two things at the same time we've got on one hand we've definitely got the asexual reproduction let's do this here sorry let me grab the annotation so we've got asexual which is um this uh plant that's been grown just kind of like the spider plant right so asexual reproduction okay and then of course where you have the actual strawberry plant because that comes from a flower that is sexual reproduction so remember flowers are involving pollen and egg and so because of that that's from two different individuals or two different kinds of genetic material and so when they come together now there's something genetically new and so that's what's happening in this flower to make this fruit with all these different seeds so those little seeds are all like completely new little babies right completely separate from each other genetically speaking and physically all right so and then if you look down here what we have is an aspen grove and in that aspen grove they look around the same age um and all of that and that's because one plant grew and then they kind of set out to for another plant to grow and so forth kind of like a a rhizome or a runner and they just are all basically genetically the same individual just separate individuals this way so that's all mitosis in the plant world now let's scoop back here that was one kind of reproduction we talked about asexual and of course now we have sexual reproduction and so um before we move on to that i want to show you here that um to get familiar with the different kinds of sexual and asexual reproduction what you want to do is an activity i think i have that in a little bit yeah we'll go back to that in a moment so um sorry so here's sexual reproduction um here you can see an egg and it's a little teeny sperm and the results of that so these are my two little kiddos they're much bigger now um my son is now 18 years old i think he's about four and a half there and this is my daughter she's about two um so yeah very different now right they've gone through some my toast has gotten a lot bigger so in an animal life cycle again there's both mitosis and meiosis when we look at animals as an adult most of them are going to be what we call 2 in that's because as a result of sexual reproduction you had genetic information from the mom one n and from the dad one in and so a mom gave you 23 chromosomes dad gave you 23 chromosomes so by putting those one ends together now it's 2n equals 46. so here these individuals are 2n they are known as diploid and diploid refers to double okay now what's going to happen as a result of meiosis once these have become adults is they will be able to form egg and sperm and we know the job of meiosis is to make half the number of chromosomes so um in that case if we're looking at that they are going to be called haploid gametes haploid means half and so we've got diploid we've got haploid so um how many chromosomes would be in each of these well you can just split it in half that's 23. so we can call that n equals 23. so these are each n this makes it easy when you say n because if the organism doesn't have 46 chromosomes to start off with instead of says has 10 and you say 2n is 10 well we know that n equals 5 okay so we're going to refer to the human one though n equals 23 and so these are haploid chromosomes they have half the number of chromosomes that you do in the adult and then upon fertilization that's when you're going to restore diploidy and so we ended up getting a diploid zygote remember that was the fertilized egg so is this 1n or is this 2n yeah it's 2n and what number of chromosomes would we have now we'd have 46. so from here 2n equals 46 and then as you know what's going to happen is we're going to go through mitosis and development okay now what i'm going to do right now is go through a life cycle of plants but not of flowering plants and that's just to show you kind of the process that we're going to go through with a flowering plant when you work on your activity so this is not the same this is for mosses the other ones for flowers okay so um in mosses what we have are um these remember these little short carpet-like plants that we talked about in the beginning of the semester so these are very small all of this is practically at the microscope level like not quite but pretty close i mean you can see them but you really have to be on your hands and knees or looking at it very closely okay so first of all we have something called a sporophyte now if you remember when we were talking about plants early on that we use the name uh fight um quite frequently with the division names remember division bryophyta division coniferophyta division anthophyta division uh sphenophyta so we were looking at this term so hopefully you remember fight and that means plant so it would be anthophyta would be flowering plants okay so that's what that means now in this case this is referring to what it produces so they're named after what they produce so what do you think a sporophyte is going to produce you got it spores so that's what we're taking a look at here is we have a sporophyte and what we know is that they produce spores by their name and these sporophytes are 2n they're diploid right and so they're going to go through meiosis now what does meiosis have to do is it making the same or is it making half well if you remember meiosis is about making half so what would the n number be for spores would it be 1n or would it be 2n well hopefully you caught it if we're looking at it half would mean that it's going to be so those fours are going to be 1n this is diploid we've made it in half through meiosis and then we've got 1n okay so now we've got a spore and the spores are going to divide more and more and more so they're going to go through mitosis and when they go through mitosis they're just going to make more of the same and each one of them is going to grow up into one of these okay now surprisingly they look the same they're actually different from each other you can only tell when you look up really close at the tip here like it's showing um these are both 1n right mitosis making the same and they are called gametophytes so gametophyte what is uh what is it going to be making based on its name it sounds like it's going to be making gametes right so that means in this case with the gametophytes it's going to be making um sperm which you know are 1n it's just making um more of the same here and it's also going to make an egg so this is a male and this is a female plant again they don't look a lot different from each other until you zoom in and you see all of these little sperm and they all have two little flagellas they have to swim to the water through the water until they find an egg so once they do if one of them does now that egg has become a fertilized egg and that of course you know is called a zygote which is diploid right because it's got one n plus one in that makes it two two n here and then that zygote is just this little purple thing all of the rest of this is still that 1 1 n haploid so this is really weird it's kind of like two individuals this is like a haploid individual with a diploid individual kind of right in the middle of it and so this purple thing is going to go through mitosis and development and then it's grow up it's going to grow up to be this brown capsule part this green part was from down here so this green down here is not the sporophyte it's only this little brown capsule thing and then of course you know that capsule the sporophyte is going to make spores so you can see here our ideas start to expand if you think about mitosis is making the same and then my meiosis is going to be making half okay