![]() Some spindle fibers grab onto centrosomes as this is going on.Ĭhromatin condensing, centrosomes moving to opposite ends of the cell, and spindle fibers grabbing on to sister chromatids. The centrioles within the centrosomes sprout spindle fibers (microtubules) as they go. (This is what we typically picture when we think of a chromosome.)Ī few more things also happen during prophase: the nuclear envelope that separates the nucleus from the rest of the cell dissolves, the nucleolus disappears, and structures called centrosomes migrate to each end of the cell. Together, each chromosome and its double form a chromosome made up of two sister chromatids joined by a centromere. Remember that each of your 46 chromosomes (that is, distinct strings of DNA) has a “double” because the cell’s DNA copied itself back in the S phase. I’m sure there are lots of mnemonic devices out there for memorizing them, but the one my seventh-grade science teacher taught me is the one I’ve remembered to this day: "Paul Meets Anne Tonight." Feel free to use something more exciting, like “Poisonous Mushrooms Aren’t Tasty.”Ĭheck out this overview of mitosis, featuring the mitosis 3D model in Visible Biology!ĭuring prophase, the DNA that’s floating around in the nucleus of the cell like a blob of tiny spaghetti starts to condense, coiling itself up super tight. There are four phases of mitosis: prophase, metaphase, anaphase, and telophase. (You can read more about replication here.) Then, in G 2, the cell continues growing and preparing for mitosis. In the S phase, the cell prepares for this by creating copies of all its DNA. But there comes a time in most cells’ lives when they’ve got to reproduce. Most of a cell’s time is spent in Interphase, the largest section of the pie-chart-looking graphic above. Just like us multicellular organisms, cells have a cycle of life. The Cell Cycle and Mitosis: You Are Your Own Clone Army How are they different? How are they similar? Keep reading and you’ll find out! Today, we’re going to talk about both of these. ![]() ![]() New sex cells, or gametes, are produced via a different process, called meiosis. Somatic cells-that is, the cells in your body that aren’t sex cells-do this via a process called mitosis. Your cells need to make copies of themselves so that they can replace old, dead cells. ![]() Still, very rarely mistakes in copying or dividing chromosomes are made, and these mistakes can have negative consequences for cells and for people.Mitosis and Meiosis: What's the Difference?ĭid you know that right now, inside your body, some of your cells are making copies of themselves? Don’t worry-that’s normal. Fortunately, our cells have amazing systems to copy chromosomes almost perfectly and to make sure that one copy goes to each daughter cell. We need each of our cells to receive exactly one copy of each chromosome, and each copy needs to be perfect, no mistakes, or the cells may have trouble following the genetic instructions. Otherwise, we might not be able to follow the instructions and things could go wrong. We don't want to accidentally give one person two copies of page four and one person zero copies of page four. With our instruction manual example, it is really important that each person gets one copy of every page. In mitosis, a cell copies each chromosome, then gives one copy to each of two daughter cells. Copy each page, then give one copy to each of two people. We can think about mitosis like making a copy of an instruction manual. ![]()
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