Presentation on theme: "Meiosis What came first, the chicken or the Egg? We learned last semester that mitosis creates new identical cells but before we can have a chicken we."— Presentation transcript:
1 MeiosisWhat came first, the chicken or the Egg? We learned last semester that mitosis creates new identical cells but before we can have a chicken we must have an egg. Meiosis explains how this happens.Student Expectation: RECOGNIZE the significance of meiosis to sexual reproduction;
2 1. How many chromosomes do you have in healthy cells? Somatic Body cellsBlood, skin, hair, bone46 chromosomesSperm Cell23 chromosomesEgg CellThe 23 chromosomes from sperm and egg combine during fertilization to make 46 in a human zygote!
3 2. What’s the difference between haploid and diploid cells? HAPLOID - nDIPLOID – 2nTwo of each type of chromosome.One from mom and one from dad.Somatic cells(Blood, hair, skin)One of each type of chromosomeInclude Gametes like sperm and egg
4 3. Let’s Review Mitosis –Define: The process of ONE cell replicating its DNA and dividing into TWO identical Cells. Type of cells: Diploid Somatic Body Cells
5 Mitosis Chromosome Count 462n4646462nLabel the n and 2n cells
6 3. MeiosisDefine: the process by which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell.Reduction Division!Type of Cells: Gametes; sperm and egg
7 Meiosis Chromosome Count 23Meiosis 22n46Meiosis 1n234646n232n23nLabel the n and 2n cells
8 Asexual vs. Sexual Reproduciton Asexual reproductiona single parent reproduces by itself. The offspring is an identical clone.Sexual ReproductionTwo cells from different parents unite to produce the first cell of a genetically unique organismMitosis!Meiosis!
9 Terms to know Sister Chromatids Homologous Chromosomes the two identical halves of a single replicated e chromosome and joined at the centromere.Chromosomes that code for the same thingOne comes from the mom and one from the dad.PaternalMaternaleye color locusB = brown eyesb = blue eyes
10 *Remember that unorganized chromosomes are called Chromatin during interphase
11 MEIOSIS is all about creating VARIATION Every sperm and egg ever made is unique because of how meiosis works
12 6. How does meiosis create variation in sperm and egg? Homologous Chromosomes Cross Over before separating and exchange genetic variation. (Gene Shuffling)
15 B. Chromosomes independently assort into gametes to increase genetic variation. (Blue eyes doesn’t always pair up with Freckles and maternal and paternal genes segregate randomly)Bbspermhaploid (n)meiosis IIBbdiploid (2n)meiosis IFfFfThis means all gametes will be different!Meiosis Video
16 7. What is the significance of meiosis to sexual reproduction; Meiosis reduces the number of chromosomes in each cell so that sexual reproduction is possible. YAY!Meiosis insures that every sperm and egg ever made will be a little bit different which means you won’t look exactly like your siblings. DOUBLE YAY!Species with more variation have a greater chance for survival! TRIPLE YAY!!!