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  • Hi. It's Mr. Andersen and I'm going to preview the genetics unit. This is

  • unit 5. If you want to check out this prezi that I'm going through, you go to

  • And it's going to show you basically this concept map and then it's going to have links

  • to all of the videos within this unit. And so the big picture within this basically I'm

  • going to talk about two major things. Number one is genes. How they're made of DNA and

  • how they get copied from cell to cell. And then more of the details of genetics. And

  • so we start by looking at what a gene is. And how a gene is defined. And so a gene remember

  • is going to be made of DNA. So the first thing that we'll cover within this unit is what

  • is DNA? What is the structure of DNA? We begin with part one with the talk of the history

  • of DNA. How DNA is put together. But more importantly in this unit we're going to talk

  • about how DNA becomes RNA. And how RNA eventually becomes proteins. And so we call this whole

  • thing the central dogma. And so in the first part I talk about DNA. In the second part

  • I'm going to talk about transcription, translation and how DNA is replicated. And this video

  • right here where I talk about the central dogma, I'm going to talk about that, really

  • the meaning of life. How cells take information in the DNA. They make a transcript of that.

  • Make messenger RNA and eventually make proteins out of that. And I'm going to draw all of

  • the parts of that. So these three videos summarize that central dogma of life. After we're done

  • with that we're going to move to the cell cycle. And so the cell cycle is how we make

  • sure that DNA gets passed from cell to cell. And also from generation to generation. And

  • so the two terms that you're maybe familiar with are going to be mitosis and then meiosis.

  • If we were to talk about the two, mitosis is basically taking one cell, let's put a

  • nucleus here and it's got DNA on the inside. And how we divide that to make two cells and

  • each of those cells are going to be daughter cells, but they're going to be identical to

  • that first cell. And so in mitosis we're taking one cell and making two copies of it. That's

  • how we go from that first cell inside you, that zygote, to the trillions of cells inside

  • your body. Inside that first cell we are diploid. So we have two complete sets of chromosomes.

  • And each of these cells remember are going to be diploid as well. In meiosis, whenever

  • you see the word meiosis, you should think about the word sex. Because meiosis is how

  • we make sex cells or how we make gametes. And so that's starting with one cell, we'll

  • make that two n. So it's got a nuclei like this. And it's basically going to divide in

  • half. And then those cells are going to divide in half. And so we're going to end up with

  • 1, 2, 3, 4 cells. Instead of each of these being identical to that first cell, each of

  • these are going to have half the genetic information. And they're also going to be totally different

  • than that first cell. And so in males each of these will become a sperm. And in a female

  • one of these, let's choose this one down here, one of these is going to be the chosen egg

  • and the other nuclear materials is going to wad up and not become anything. And so that's

  • meiosis. And so basically mitosis is how we copy all of the DNA and make sure that it

  • ends up in each of the different cells. A better way to define what mitosis is is simply

  • nuclear division. It's going to be part of the cell cycle. But meiosis is how we create

  • different nuclei in each of those. Remember, sex cells. And so that's the cell cycle. And

  • then the next thing we're going to cover in the genetics unit is going to be genetics.

  • And genetics is two fold. Genetics is going to be Mendelian genetics. And so in Mendelian

  • genetics we're going to to do genetics of Mendel. And so this is Gregor Mendel right

  • here. Gregor Mendel, you've probably heard of this, was a monk. Studied genetics. Studied

  • pea plant characters and traits. He actually dies in obscurity. Nobody really pays attention

  • to him. But you've learned a lot about Mendelian genetics hopefully throughout your science

  • career. It's how we take lets say these are purple flowers and these are white flowers.

  • And if we take purple flowers that are hybrid. Cross those with purple flowers and so you've

  • done those punnett squares before. So this would be big P little p big P little p. So

  • if you've done those and figured out this is going to be a three to one ratio. So that's

  • going to be all the work of Mendel. So he figured out that we've got basically the idea

  • that we've got genes. They're passed from generation to generation. You've got two genes.

  • And you're going to give one of those randomly to your offspring. The idea of independent

  • assortment. So that's the Mendelian genetics or basic genetics. And then we're going to

  • deal with advanced genetics. And so advanced genetics doesn't mean it's any more complicated.

  • It's going to summarize the work of this guy. This is Thomas Hunt Morgan and his work with

  • fruit flies. But basically what we figured out with advanced genetics is that Mendel's

  • laws don't always work. Lots of times the genes are on the same chromosome and so you've

  • got gene linkage. We also figure out that in some genders there are going to be some

  • genes that are found on the sex chromosomes. And we also add to this multigenic inheritance.

  • And so traits for example, like height that are caused by a number of different genes.

  • Incomplete codominance. So we're going to add a lot of things to that. And so that's

  • genetics. Non Mendelian genetics. And then that last thing that we're going to talk about

  • in this unit on genetics is gene regulation. And so basically if you look at a cell. So

  • if this is a cell on the inside it's going to have DNA. But not all of the DNA is going

  • to be expressed. In other words not all of the DNA is going to make messenger RNA. And

  • then make proteins. So, that's kind of bad writing, but in this unit on gene regulation

  • we're going to talk about how we can turn genes on and how we can turn genes off. And

  • that begins with a discussion of the operon which is found in bacteria. And it's a simple

  • way that they turn genes on or genes off. And then in eukaryotic cells we're going to

  • talk about transcription factors and how they can turn a series of genes on or genes off.

  • And so that's how we'll finish out the unit on genetics. And so that's a preview of the

  • unit to come and I hope that's helpful.

Hi. It's Mr. Andersen and I'm going to preview the genetics unit. This is


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遺傳學預覽 (Genetics Preview)

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    Cheng-Hong Liu 發佈於 2021 年 01 月 14 日