Скачать с ютуб Meiosis! (Mr. W's Music Video) в хорошем качестве

Meiosis! (Mr. W's Music Video)

Get Mr. W's Ultimate AP Bio Course Outline! Your first step to AP Bio Success: https://apbiosuccess.com/AP-Bio-Outline TEACHERS: Start with a free-trial account that gives your students access to interactive tutorials and allows you to monitor student work: https://learn-biology.com/ap-bio-teac... PARENTS: A guaranteed 4 or 5 for your son or daughter on the AP Bio Exam: https://learn-biology.com/parents/ STUDENTS: Crush your biology course with interactive lessons with flashcards, multiple choice questions, FRQs, and interactive diagrams: https://learn-biology.com/l-b_student... PROFESSORS: Help your students master the most complex topics in biology. Sign for a free trial at: https://learn-biology.com/college-bio... SUMMARY: A five minute musical explanation of how meiosis creates variation! Lyrics Meiosis, it's how we make sex cells, or gametes The sperm cells or egg cells performing the feat Of moving genes forward in eukaryotes like orchids and bees. Meiosis doesn't happen in all cells of the body There's just a few cells that have this hobby I'm talking 'bout germ cells in testes and ovaries, Germ cells are diploid and what that means, Is that the chomosomes are matched up in teams, In each pair one's from your dad, one's from your mother. And when you line up the chromosomes it's suddenly clear How each is a member of a matched up pair, Homologous pairs, each a homologue of the other. In humans,the diploid number's forty six, And a key trick that happens in meiosis is dividing that number in half to 23 And that single set of chromosomes has its own name It's called "haploid" in this meiotic game. So diploid to haploid's a key meiotic strategy. CHORUS Meiosis, makes eggs and sperm It's the same in the robin as it is in the worm. Makes haploid gametes with recombination, Meiosis creates variation! In interphase I meiosis starts, It's the DNA replication part An evolutionary relic of its origin, 'Cause meiosis evolved from mitosis you see, So each process starts identically Replicating chromosomes into two sister chromatids. In Prophase I chromosomes coil up, and homologous pairs pair up, Forming tetrads, each with chromatids four. A chiasma's the spot where the chromatids link And synapsis is the name for the whole darn thing, And crossing over is what this whole process is for. See the homologues aren't identical twins-- no way! They're not the same DNA The genes are the same but the alleles might take different forms, So during synapsis alleles can cross over, Between homologues, and when it's all over, There are gene combinations that have never been seen before. CHORUS Another meiotic variety creator, Is metaphase one with homologues at the equator, Cause how each pair lines up is random and independent, So in one pair facing north might be the maternal, In the next one it might be the paternal, It's a one in two shot, it's called independent assortment. So two pairs divide up in four distinct ways, It's two to the number of pairs, you could say So think 'bout us humans with 23 homologous pairs Two to the 23rd power is a number so great, Is 8 million,three eighty eight thousand, six-oh-eight That's why metaphase one is a variety creating affair And now connect this assortment with recombination, Note that what we've got during gamete creation, Is sperm and egg cells that are absolutely unique So if you ever wondered how sisters and brothers, Can be so different from one another, Remeber these meotic recombining techniques. BRIDGE And if meiosis had never evolved The book of life would be a very different tome. Cause if it wasn't for meiosis All offspring would be clones! Metaphase one: homologues at the equator Anaphase one: they say "see you later" It's like Mom and Dad splitting up and setting up new homes. Two nuclei form in telophase one, Then cytokinesis-meiosis one is done, We've got two haploid daughters, still with doubled chromosomes. Now things are much simpler in part two of meiosis Essentially it's like just mitosis, You just need to pull those sister chromatids apart, They line up in the center in metaphase two Anaphase pulls them apart we're almost through, Telophase, then cytokinesis, we're at the last part. CHORUS