Bio review

There are some little stickers and you can't in the stockroom I just umm all right so To be able to answer you also have to know the difference because you're going to have OK this one diploid number of say 6 how many chromosomes am I looking at are they replicated or unreplicated OK all those kinds of these kinds of questions will be on your final exam pictures solves problems so if you play the card game and like when I made the card game I took pictures of it and like I laid out the cards and it was like OK this is what it looks like if the cards are in place this is what they look like if they're investing so this is what they they move around a certain way and that should help you prepare for your final exam I'm not going to show you pictures of cards I'll show you pictures of really simple cells chromosomes but like the card game is the right Claire all right cool this little clicker thing because it gets to something that seems to be confusing for our society as a whole which has to do with stuff like sex and gender and despite what some people might say all right these things biologically OK or whatever I think it is my responsibility to teach you some of the nuance that can happen in terms of sexual development and differentiation so we'll talk about how things frequently go and we'll also talk a little bit about how things can go OK and it's biology students it's important for you to understand that like in most topics in biology it's like yeah here's what usually happens and then here's the stuff that can't happen too and it's not like it never sort of impossible events that sometimes happen too OK so we are talking about women's sexuality in schools all right from a biological perspective this is just one example of an athlete yes are you going to go over the like exam today OK and the keys are out in labs so look at your keys and then if you have any questions like I'm very happy to if I'm not your lab instructor which I will be if you're in the lab for the rest of the week if you want to go through the key with me I can help affect you because one of the things that I think is really useful thank you that's perfect a lot of times it's super helpful if like the questions you missed on the exam that we talked about like what were you thinking like OK maybe you picked the second best answer but I wanted the 1st test you know or maybe you just like thought that this sounded better because it had more words in it or something like that you know and those can be strategies that help OK one thing that I if you're someone that looks at your scantron and you're like Oh my gosh there were 5D's in a row like I don't play with that like I don't care it doesn't you may I'm not thinking it would be statistically likely that you can get an exam where ever correct answers see I don't know I'm not going to mess with it you guys if you haven't noticed if you've ever looked at the different versions like you all get the same questions but they have to be in different orders and the right answers have to be in different orders so I scrambled your tests to make sure that they are all different ordered in terms of the questions and the answers by the time I do that scrambling I also don't then do another thing where I'm like OK I don't have more than three season around like Nope put on here OK so if you're ever looking through your scantron and second guessing yourself on whether or not I would put the 5D or whatever like I don't care so I don't change it you know it won't so don't think about that OK so anyway so this is like a top all right you're probably familiar with the example of a female athlete who has had an accusation of you know sexual differentiation or you heard something there are plenty of examples and high level sports right testing is a long history and very competitive sports like the Olympics if you're interested in something that's more interesting to me as a biology teacher is what does it mean to be male or female OK one it depends on the Organism OK like sexual differentiation that prevents changes a lot among different organisms if we're talking about humans and organisms that don't regularly have sexual switches and adults all right we're talking about whether or not an Organism makes for perfect OK organisms that make eggs are considered female even if they've previously made sperm OK if they make sperm they're male all right the only difference between eggs and sperm from a biological perspective is eggs are considered the bigger gametes sperm of the smaller gaming if the games are both the same size we actually don't call them things in the spirit so that's the basic biology now again most biologists will argue that there are OK so to make to get to the point where someone makes fully developed games which is what we're talking about when we talk about meiosis OK that has a number of different genetic and physiological components OK and those can align with the typical arrangement or maybe not alright since we're talking about the process of being osis which is the process of cellular division that produces gaming so eggs and sperm we're going to spend a lot of time talking about the division of chromosomes and the presence or absence of things like sex chromosomes OK so remember it's your job to read your book it's your job to watch talk about sex determination and humans like to talk a little bit about some other organisms because not all organisms use the same sex determination system that we use all right we're going to talk a little bit about sex determination in humans alright so but when we talk about sex and humans whether we identify as someone male female or somewhere in between we look at things like anatomy all right So what are their primary and secondary sexual characteristics all right do they have production and things like that all right do these organs function in the way that typically results in the production of eggs or sperm things like that alright their chromosomes now one of the problems that typically happens with groups trying to categorize humans in terms of their sex is they want to look at just say one of these characters OK let's just look at their chromosomes OK and after you study the chapter on meiosis you'll understand that not everybody is going to have either an X OK on this junction events which is the thing that you'll see on your final exam and nondisjunction event is on the chromosomes fail to separate normally OK you can end up with more or fewer of these chromosomes OK you guys are probably all familiar with Down syndrome all right Down syndrome is an individual has three copies of their 21st chromosome Down syndrome is one of the more familiar trisomies because many other trisomies when monies are fatal so you don't often see people that have them all right but that is an example of a non disjunction events OK during normal meiosis one copy of each homolog is supposed to be distributed to alright when someone who has Down syndrome they have had either the sperm or the eggs contribute 2 copies of that 21st chromosome so but you can have other changes too like physiological changes anatomical changes so there and this is just given all of the levels that biologists necessarily look at when they talk about human sex differentiation OK but for our classmates midnight all right so something that you do OK so type is a sustained visualization of chromosomes. Types are frequently done when a chromosomal abnormality is expected for suspected OK so sometimes they're done checking for various types of chromosomal abnormalities when you look at your chromosomes OK so remember we're going to be talking round around the histone proteins those are kind of like field organizers if you've ever like pulled over in a file folder it's full of papers and if they weren't organized it came credibly difficult to find the papers that you have hanging file folders and organizers you're like ohh I'm looking for something for my taxes so that's like these histone proteins help to also package it up really nice and tight and whatever it's nice and tight after pressure from the location Yep you're attached to each other identical to each other OK so you want to write sister chromatids umm but this is like the first time OSHID identical promises are identical in parentheses unless until crossing are identical unless until crossing over your comments are identical unless until approximately over and then you write equal signs same jeans same positions same lens OK they have the same versions of the house they are copies of one another OK sister chromatids are formed during DNA synthesis a replication alright they are identical copies of each other until crossing over first OK crossing over only occurs in prophase 1 will be on your final exam OK in this example this chromosome and kind of looks like an X this joined together like attention mayor alright that's gonna be what we staying and hue and aquarium type OK and this one happens to be right because we see the two sister chromatids are strong so there is an example of a carrying this one kind of like looks like it's not replicated but if you look really closely here you can see like there's a little gap between each of these so these are actually replicated and you see how chromosome one has two replicated chromosomes on it everyone say it with me chromosome one has two replicated chromosomes OK those are the homolog OK so you want to write underneath your discussion of sister chromatids homologs have the same genes at the same maybe different alleles dogs have the same genes at the same positions but maybe differently have the same genes at the same position but maybe differently OK because like I don't know which gene we're talking about OK and some organisms that make the only one version of the gene OK but in other organisms there could be thousands of versions of the gene OK it just depends alright so that's why there's this maybe OK when we get into genetics if you are looking at an Organism that's homozygous that means it has the if it's heterozygous they have different buildings yes OK so here you're 2 OK so it's 6X and Y don't actually look like X's and Y's alright and I forget the story on the way they got named alright so but the Y chromosome is very small OK this is kind of important when we talk about sex linked traits so in chapter what are we in now we did 12-13 in chapter 14 when we talk about genetics and then chapter 15 when we talk about like just thought polygenetic sex linked traits are either found on the X chromosome or on the Y chromosome the Y chromosome is very small it typically only has genes associated with male development in humans like it has some other stuff mostly that's what it has OK whereas the and the X chromosome has genes related to other stuff like in humans red green color blindness OK that gene is located on the X chromosome alright so for a carrier type OK so here's some important stuff to remember and diploid organisms you have two versions of each chromosome one from mom one from dad all right humans have 23 final exam just because like and ** typically results in female development the presence of an X chromosome and Y chromosome typically results in male female so you can watch this thing on how you make carrier Times Now there are instances where you can get abnormalities in the distribution of sexual problems OK affects the structure it can be caused by missing damage or texture of sex from zones alright so one of these are ones that your book talks about Turner syndrome is a monosomy so individuals who have Turner syndrome typically have external female Physiology and anatomy and Physiology however they're missing one of their ex because there is extra stuff on the X chromosome there are some conditions that are kind of affiliated with partnership from not gonna get don't spend time studying the specific characteristics of your Turner or kleinfelder or any of these other symptoms just be aware that they exist OK all right somebody who often shows male external physical often the presence of a wide chromosome is going to lead a fetus into that individual into a male pattern of development OK and this gets into like how you know a developmental biology but there are specific scenes on the Y chromosome that when they get activated they trigger a pattern of male development OK so before like seven weeks of gestational age fetus is neither male nor has characteristics then if that chromosome works properly might put it on the path toward male or female developments OK I really like male development because male development gets like on all right because of genes on the Y chromosome alright I'm going to a little bit all right let's see here so again all adult humans can have fairly normal anatomy and have one of these sex chromosome abnormalities OK again don't spend time on your studying for your final exam about the specifics of them all right but like in this instance OK so here's our first quarter replicated or unreplicated pretty clear OK and just for clarity I'll tell you it's on replicated OK I warned you that it might be hard so I'm just going to tell you right now if you look all right there are no little bits where it looks like there's two arms that are just like nudged close together this is unreplicated DNA OK this is not your most common most carriers will show a replicated push on replicated we'll do that specially thank you thank you and five yes huh because like remember replicated chromosomes have identical sister chromatids attached to the center that will be on your final exam OK maybe I'll show you a picture and be like is this a replicated or unreplicated OK this these are homologues of the same chromosome 19 OK and they are attached alright thank you now here's a question XXY genus so remember I told you that X&Y chromosomes that don't look like X or Y OK I told you that the Y chromosome just looks a lot smaller than the X chromosomes chromosome is a lot smaller than the X chromosome is it primarily contains genes related to male sexual development again I'm feeling generous alright this is a wide chromosome alright all right then 5:00 and 4:00 3 all right all right now we're going to go through the old school like what's the process of this OK humans that are deployed all right it's called an egg the eggs and the sperm because they are both half blood cannot develop into an adult human on their own they have fused together to make a zygote the zygote is what we refer to that first diploid cell all right and then that side goes undergoes many many many many many many rounds of mitosis becomes a multicellular individual the process starts over OK this is the human life cycle all right now when we are talking in another way to say that OK so again the whole purpose of meiosis is to create daughter cells that have half the chromosome number of the difficulties they have one of each of the homes not alright because sperm and eggs are supposed to be fused together and that get back to the normal chromosome so when we're talking about like if you I want you to practice drawing these things OK because you will see drawings of them on your final exam and then we do better at answering the questions that follow if you're familiar all right so OK this is 1 chromosome of a homolog but now it's replicated OK so if I show you this if I show you this and I say one of a pair of diploid sets of chromosomes replicate it still happened OK OK this is the diploid representation one from mom one dad these are diploid but replicating OK this part gets people confused you're like but I see that there's four times as much DNA as there was like OK yes there is there are four sister chromatids but because these two are genetically identical to each other what is the first thing I made you write down today sister chromatids are genetically identical to each other until crossing over because this is exactly the same as we don't count it as two different things we count it as the same thing but it's replicated OK I'm going to warn you I know I haven't asked this question in a while but sometimes I will and if you guys are not in the right order maybe I'll meet you all right I could ask you a question about chromosome OK this is 2 chromosomes this is to chromosomes so I ask you a question about amount of DNA alright then I'm not asking you about chromosome number I'm asking you like hey how much if you were to weigh out this DNA how much would it weigh in the right answer would be ohh it weighs 4 times whatever that thing weighs OK does that make sense all right so even though you have more alright if it's not different when I ask you a question about chromosome number you answer it like hey we have two chromosomes here they just happen to be replicated OK but if I tell you a story where I tell you about the mass of DNA and you're like wait a second that's twice as much or times as much as living cells to start thinking like OK how many sister chromatids are present because I could then ask you something about a stage of meiosis OK like hey the gamete had this much DNA in it OK but you found a cell that had if I do something like 4 times as much OK you have to I think to yourself OK if the game had ex and you're looking at a cell that has four XI know that that cell has replicated chromosomes do you see how it sounds like there's so basically I'm just giving you a piece of information that's supposed to relate back to some part of phase of meiosis where the sister chromatids have not split OK if I wanted to be tricky that's the way I could be tricky OK so alright here's the question this chromosome is composed of two chromatids joined by descent which of the following statements is true you guys can see this better than I do you can see it here on your phone I can't see you OK OK I'm going to help you with this OK this person is composed of two chromatids joined by senator which of the following statements is also true these chromatids make up a diploid chromosome is that true diploid means this either came from mom or death OK but because we're looking at replicated chromosome where we've got two sister chromatids attached to the seminar alright this one and that one are genetically identical to each other so get that first answer is wrong OK it is not the service contains these sister chromatids must be deployed no you could see this cut this arrangement in any any part of a cell that's gone past meiosis 1 so I should say in any part of any cell phase in meiosis 2 OK and meiosis one we separate the home locks and miosis 2 we OK so there's not enough information to tell whether this cell is in applewood or in diploid phase OK these sister comments were formed by replicating a single comment joined by fertilization bringing together maternal and paternal no that's not how it works OK we never confuse maternal like 1 maternal sister chromatid and one internal that's not how it works all right I 100% will ask you questions on your final exam what is the mitosis daughter cells are genetically identical to each other and to the parents of this form them for the purposes of growth development asexual reproduction like budding or blah blah blah OK meiosis is about making a gift that's the purpose whenever we get into the phone guy and things like that you'll get to learn other stuff OK so another way you could say is meiosis is about making daughter cells with half the chromosome number so once again this is 100% of your final exam what stage do the homologs separate homologs separate the meals this morning what stage does sister chromatids separate sister chromatids separate Yammer on about it videos there all right touring with normal number final exam where I don't ask you about the three sources of genetic variation that happens in the sexual reproduction and you will very happily write things like crossing over in prophase 1 of meiosis results in unique combinations of alleles that never existed before and then you'll write an independent assortment in metaphase allows the homologs from line up and totally different arrangements which result in different daughter cells and then three you'll say the fusion of gametes resulting combinations of alleles that you will write those three things you will feel very proud of yourself you're supposed to accomplish all right so no good OK And Paris there we go this is the term you need to know it's not excel these body cells also think about it as not 3 all right so final exam all right at the end of the first stage of meiosis one the two cells are already halfway OK don't forget that alright if I'm like at what point during meiosis do the cell the daughter cells become haploid you say at the end of meiosis one OK even though the sister or have not separated yet alright because the homologues have separated we call those daughter cells happen OK if you were to measure the amount of DNA it would be the same as the parent cell but the information there is only half of what was in apparent so OK because the whole law all right so whatever information was on the maternal chromosome 2 is in one daughter cell and it's not in the other OK whatever information was on the paternal chromosome 2 is it was one daughter cells but not the other OK now in the second division alright because the homologue breakfast and big giant ask capital letters alright ohk separated meiosis 1 ohh along separate videos this one do you want to get super technically Miller separating and they're really great totally like suffering suffering I will want you to go home on separate promises breaking them apart they are no longer attached with the seminars then they go off into alright I'm not going to go through all these like animations because you can do that at home but maybe I'll like post them on Thanksgiving here big capital letters Yes but that's the thing that I want you so maybe whenever you're studying your little group of people who are super helpful to you you're like practice and try to find ways to trick your friends OK because that's how you can like start to think about ways that I add question our answer choices that are like a little alluring but still incorrect OK so 4321 two what happened 3 all right ohh my gosh I love independent assortment so much good player card game again that's why I like to do 3 different types of chromosomes because you know it's a little easier to see a different kind of starting with three instead of it's good any more than that it's working OK so here's the difference OK this is showing you it with just two which again I like to show these three I think in the video maybe I did 3 anyway internal here we have the two maternal homologs lined up towards the left and the two paternal ones lined up toward the right OK but the thing to remember about the other one is the whole logs all line up like independently of each other so so we're going to go on the right side OK it's random alright so each pair of chromosomes everyone write this down it's gonna help you answer questions all right there's two different options I'm going to pretend like cells have left and right because that makes sense OK like mom can either go to the left or mom can go to the right OK it's like dad dad can go to the left or dad can go to the right OK for each pair because each pair of homologous has that mom to the left or mom to the right option OK that means that it's not like ohh there's 2 2 or whatever different ways it's 2 to the 23rd different ways human cell can line up in metaphase 1 of meiosis OK because each homolog has two options and there are 23 homologs so it's 2 to the 23rd power OK that's how many different ways a human cell can line up on the metaphase one plate immune system OK each cell has two or each homolog has two options but since there are 23 pairs of chromosomes there's two of the 23rd different arrangements OK if we were talking about I think drosophila have like 4 chromosomes OK or maybe they have 4 pairs of chromosomes so it would be like 2 to the fourth OK like 8 comes on if you go to genetics and I was wrong my God they would only have two to the fourth different options because there's four pairs of homologs OK and again because you have one home love from mom and one from dad OK and they can go either way so chromosome 1 OK so let's see here and this is how so we see our arrangements so this is kind of like just showing all the different phases OK so right at the top here like if you were to print these up close this up if you were to print these out you would be like this these cells are in metaphase one OK the homologs are lined up on the metaphase plate like if I ask you to distinguish between a cell that is in metaphase 1 of meiosis versus metaphase of mitosis and mitosis all the chromosomes line up in a single file line OK Phase 1 of meiosis the homologs line up so you have like a double line does that make sense I love to put questions on your final exam about that where I show you a picture and I'm like hey what phase is it OK if you see a single file line it is either so just write this single file line of chromosomes it's either metaphase of mitosis metaphase 2 of meals alright you have to know the number of chromosomes to tell the difference between if it's a single file line with the diploid number of chromosomes you are looking at mitosis metaphase OK because you know that the cell is already haploid at the end of meiosis OK so I would have to tell you what the normal chromosome number is I can't just show you a what phase is it because you have to know what the normal chromosome number is to determine between metaphase and mitosis and then in Phase 2 of meiosis OK but if all the chromosomes are there you're looking at a cell that is in metaphase of mitosis OK if only half the chromosomes are there you're looking at metaphase 2 meiosis OK and if you're seeing a double line of chromosomes that's metaphase 1 theosis line up together OK so be prepared let's see that's all right how many possible combinations of maternal chromosomes in a human egg due to independent assortment all right it didn't show it didn't do it right I'm going to just give you the right answer OK so remember 2 to the number homologous pairs OK so a human egg can have two to the 23rd OK pull everywhere doesn't keep formatting so when I put this answer in it was 2 with superscript 23 I forgot that it doesn't keep formatting very well so I just put it together OK 2 to the 23rd is about 8,000,000 OK you are not going to have to remember something like ohh there's 8 million different combinations and the formation of the single games but you should remember that there is 2 to the power of however many cars OK so like that's just something 2 to the 20th alright and that's what I'm wanting to do here if it's information that Jack all right so everybody alright 54321 alright what happens during crossing over OK I was really harping on mulligan's chromosomes have the same size they have the same shape they have the same centromere position they have the same genes at the same position I was harping on that on Monday because all of those things have to be true for the process of crossing over to occur crossing over the two homologs right over each other and basically align segments of the DNA right next to the corresponding parts on the other home alone OK so the genes line up say this is the gene for if we're talking about say drosophila eye color OK because there's not one in humans anyway these proteins that are holding them close together allow enzymes to come in and sniff them and swap them OK so one of the things I want you to write down is though you'll want to have to remember this for your final exam crossing over new combinations of alleles that never existed before on that sister Crompton passing over did never existed before like this before crossing over occurred this sister chromatid you guys can see the one that I'm using my little pointer on this is for chromatin is exactly identical same gene same alleles as this one before crossing over these two sister chromatids were exactly identical to now this is not identical to the one across the centuries properties OK so another way you could say this is crossing over creates non identical system problems that doesn't really summarize why it happens though OK it's it's telling you what has happened but it is for other explanation I gave you tells you why it happens crossing over has an evolutionary advantage of creating combinations of ideals that never existed before OK this combination of say go sleep pattern probably never existed before OK this combination of mostly maternal but a little paternal never existed before it wasn't what was in mom OK and this is not what was in dad it's a different arrangement of alleles that never existed before OK and these were then get passed on to the games where does crossing over crossing over occur happen in mitosis crossing over is is strictly miotic says that it happens in prophase 1 of meiosis it does not happen at all in mitosis it creates unique combinations of alleles that never existed before OK so this is one of the ways that sexual reproduction creates new genetic diversity in populations OK whatever damn all right probably ever that makes sense now you said this is crossing over strictly yes it does not happen in mitosis I love to ask questions on your final exam like oh oh I'd ask this when does it happen in mitosis and the right answer being never it doesn't but something like that OK I would make it a little bit more smooth but like eventually like there'll be a question like do you understand this doesn't happen in my OK so this is one of those 3 mechanisms that I'd love you to be able to talk about OK and then it happens in prophase 1 of meiosis does not happen in mitosis it doesn't happen OK now one of those things let me go back on the Jillian slides real quick so if you look at these homologs you can see they've been dyed the dyes correspond to like different parts of the DNA that we're attracted the dystopian way out of the blah blah blah all right but like you could expect the crossing over could occur between the parts that have the same color OK and like you can see that you're like ohh OK all right then do align with each other which is how they line up the way they're supposed to in meiosis OK because they have to recognize that they are homologues of each other and they do have to line up together on the metaphase plate so there's little pieces of DNA that tips that allow them to recognize each other as we're going to talk about 30 seconds alright so during crossing over all of the following except All right good crossing over is about increasing genetic variation alright so we talked a little bit about sex determination in mammals males typically get 1X chromosome and one Y chromosome females typically get 2 all right of the zygote because either like the sperm is either going to have an X or Y whereas all eggs because females are * all eggs carry exponents ohh let's see here something like this all the eggs 5050 so I will post these up so you guys can play with them whenever you want to make practice so I told you that there are these regions on the work as homologous pairs when we talk about how they line up but they're not like really homologous because they don't carry the same genes the X chromosome has very different genes than the white Chrome alright and like I said the Y chromosome mostly has a lot of genes associated with male development OK so here ohh actually showed up here but so basically the only reason that these two different chromosomes arranged like OK so the very tips of those chromosomes do match up they can participate in some crossing over all right again there's one last thing that we can talk about and what determines sex and humans are specific genes OK so the one that you're both talks about YRG Alright so the six determining region of the Y chromosome gets located pretty close to that pseudo autosomal region OK or just you could say the tip that allows these two to behave like homologs all right when in like the 7th normal male development gets turned on and starts express Because you guys are biologists you'll often deal in the most of the time but then there's also some other we know that genes can get damaged during DNA replication OK or that they can get by modification like we all sorts of things that can happen where a gene doesn't work the way that it usually would or does it end up where it often would OK and because of SYR gene is located toward that tip sometimes you can get them to process OK crazy things happen so yes SRY gene can get moved from a Y chromosome during this process the sperm development OK sperm production you could get damaged during DNA replication you don't function properly you can have lots of things happen so everybody pushed the all right all right so again the main point of this though is that you can get different someone can have an X karyotype but their X chromosome has gotten SYSRY gene moved over to it during a crossing over event or you can have someone with an XY carry those type where that SRY gene has been deleted or damaged or otherwise nonfunctional OK and in that case because that SRYG is so important to triggering male development in utero if it doesn't get turned on you're not gonna see there are individuals who have extraordinarily female presentation for the anatomy who have karyotypes that would indicate they have the X&Y chromosomes OK and that can be because that what that Y chromosome carries a damage from missing or somewhat somehow otherwise nonfunctional and therefore that fetus never pattern of development I'm done alright anyway I ask you about crossing over because I think it's super important and the big thing that I want you to remember is that crossing over creates unique combinations of alleles that never existed before crossing over occurs in prophase 1 of meiosis any other type of solution OK this also went through a little bit of independent assortment which I equally love OK so independent metaphase one of the one of the houses and then also talk a little bit about that last way that you can create an accountability and such why else do we talk about this because you guys are biologists and apparently in this country we've stopped learning that things can be weird in biology I don't know how that happened whatever alright but if someone wants to tell you that like there's only two biological sexes like that's not biologically accurate OK because the term section comes along and people do and would be either swapped over YRRY OK so you can have two extremes extremes don't usually have SRY genes on them but nothing in biology is always OK there's usual and then there's kind of unusual OK it is not usual to get an SRY gene on an X Chrome impossible likewise most why chromosomes do carry the functional genes but not all of them OK there are plenty of instances where people have genes that don't work and we know that happens in all sorts of things not related so it's not shocking them it also happens and things related to sex OK and it's sexual development has so many layers to it it's that what we look like on the outside is what we're going to do on the inside it's what our chromosomes look like inside our DNA and it's what our genes are doing with those chromosomes OK so it's just complex and it's future biologists I think it's important to understand some of that so let's switch over I don't know if I'm gonna make you guys do the yeah