Meiosis

VOCAB THAT MUST BE KNOWN Ploidy: 1n, Haploid 2n, Diploid Chromatid Homologous chromsomes Tetrad Crossing Over

9. 9.Meiosis Sexual Reproduction Asexual Reproduction Chromatid Chromosome Genetic Recombination Fertilization Independent Assortment Write Down… ALL THE Key Terms! 1.Prophase I 2.Metaphase I 3.Anaphase I 4.Telophase I 5.Prophase II 6.Metaphase II 7.Anaphase II 8.Telophase II 17.Ploidy 18.Haploid (n) 19.Diploid (2n) 20.Tetrad 21.Homologous Pair 22.Crossing Over 23.Somatic Cell 24.Germ Cell 25.Gamete 26.Zygote nb - You have to actually define them to get credit at the end of the unit

Bellwork Obj: Describe the process of meiosis 1.What are the 4 stages of mitosis? 2.Is interphase a part of mitosis? Explain. 3.What is the purpose of mitosis? 4.What is the difference between sexual reproduction and asexual reproduction? Give an example of a species for each. 5.Which type of reproduction would be more advantageous in nature and why? Explain in 1-2 complete sentences.

On science fair boards:

Each of the nucleus of your cells contains all this: Special cells in your body only have ½ this amount. Where? Why?

Long red: mother/chromosome 1 Short red:Mother/chromosome 2 Long blue: father/chromosome 1 Short blue: father/chromosome 2 Each gamete has: 1 MIXED copy of chromosome ONE 1 MIXED copy of chromosome TWO Each somatic cell has: 2 copies of chromosome ONE -1 from mom, 1 from dad 2 copies of chromosome TWO -1 from mom, 1 from dad How to create a gamete: Meiosis Or ‘How to create an egg or a sperm’ Make a copy!

the diploid somatic cells of an individual contain one copy of the chromosome set from the sperm and one copy of the chromosome set from the egg; that is, the cells of the offspring have genes expressing characteristics of both the father and the mother.somatic cells

A gamete (from Ancient Greek γαμετή gamete "wife" [1] ) is a cell that fuses with another cell during fertilization (conception) in organisms that reproduce sexually.Ancient Greek [1]cellfertilizationorganismsreproduce sexually A gamete's chromosomes are not exact duplicates of either of the sets of chromosomes carried in the dfs chromosomes.

CROSSING OVER GAMETES23=N HAPLOID SOMATIC46=2N DIPLOID MITOSISMEIOSIS

In humans, an ovum can carry only an X chromosome (of the X and Y chromosomes), whereas a sperm may carry either an X or a Y; thus the male sperm determines the sex of any resulting zygote, if the zygote has two X chromosomes it will develop into a female, if it has an X and a Y chromosome, it will develop into a malehumansX chromosomeY chromosomessexzygote

Long red: mother/chromosome 1 Short red:Mother/chromosome 2 Long blue: father/chromosome 1 Short blue: father/chromosome 2 Each gamete has: 1 MIXED copy of chromosome ONE 1 MIXED copy of chromosome TWO Each somatic cell has: 2 copies of chromosome ONE -1 from mom, 1 from dad 2 copies of chromosome TWO -1 from mom, 1 from dad How to create a gamete: Meiosis Or ‘How to create an egg or a sperm’ Make a copy!

Mitosis vs Meiosis Mitosis  Body cell division (cloning) Mitosis makes “my toes-es” Meiosis  Making sex cells (halving) Meiosis makes “my OH…baby!”

Meiosis _________________ is the process that ___________________ cells undergo when a single cell ____________ to make ___ unique ________________ daughter cells Meiosis Somatic (diploid) divides 4 haploid

Meiosis Explain to your partner 1.How many original cells were there? 2.How many cells did it divide into? 3.Were all these new cells the same? 4.What do we call the new cells?

How do Organisms Reproduce? Organisms either reproduce sexually or asexually. Meiosis only occurs in ____________________species Sexually reproducing

Asexual reproduction Asexual reproduction involves formation of a new individual from cells of the parent, without meiosis, gamete formation, or fertilization.

Question???? So, why, if an animal is reproducing asexually, does meiosis NOT occur? Asexual reproduction involves formation of a new individual from cells of the parent, without meiosis, gamete formation, or fertilization.

Sexual Reproduction In sexual reproduction the ______________________ of one parent are _______________ with that of the other parent to produce a __________________ _________________ offspring. chromosomes combined genetically unique

Meiosis Video 9tA 9tA

Fill in the diagram as we go Meiosis I Meiosis II

Prophase I __________ form and ___________ _______ occurs! Tetrads crossing over

Tetrads & Crossing Over Tetrads- ______ association of sister chromatids of ____________ _____________ (4) close homologous chromosomes Crossing Over: Homologous chromosomes _________ small pieces, resulting in ____ chromosomes! exchange NEW

Tet Cr-O 1. What are ‘sister chromatids’ – Why did we keep them together in mitosis? 2. What are ‘homologous’ chromosomes? -Genes for eye color and height are both on chromosome 11 for humans.

Metaphase I

Anaphase I _____________ _____________ occurs creating _____combinations! Independent Assortment new

Independent Assortment Chromosomes from the _____ & _____ _________ move to one side or the other mom dadrandomly

Telophase I

(Cytokinesis)

Long red: mother/chromosome 1 Short red:Mother/chromosome 2 Long blue: father/chromosome 1 Short blue: father/chromosome 2 Each gamete has: 1 MIXED copy of chromosome ONE 1 MIXED copy of chromosome TWO Each somatic cell has: 2 copies of chromosome ONE -1 from mom, 1 from dad 2 copies of chromosome TWO -1 from mom, 1 from dad How to create a gamete: Meiosis Or ‘How to create an egg or a sperm’ Make a copy!

Prophase II

Metaphase II

Anaphase II

Telophase II

(Cytokinesis)

Summary of ways Meiosis is different from Mitosis Involves _________________________________________ 2 consecutive cell divisions

Summary of ways Meiosis is different from Mitosis Ends with ___ cells that are all _______________ (sex cells: _______& ____) 4haploid spermegg

Summary of ways Meiosis is different from Mitosis Makes _____ _________________ combinations through ___________ ______ and _____________ __________ NEW genetic crossingover independentassortment

Meiosis Card Sort Order the 11 cards to show the progress from a single cell in interphase and progressing to 4 haploid sex cells

Funny Meiosis Video Kt8 Kt8

Slate Quiz! Look at the pictures on the following slides & name the stage of meiosis!

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