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Mitosis and Meiosis Asexual v. Sexual Reproduction

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Presentation on theme: "Mitosis and Meiosis Asexual v. Sexual Reproduction"— Presentation transcript:

1 Mitosis and Meiosis Asexual v. Sexual Reproduction
Cell dIVISION Mitosis and Meiosis Asexual v. Sexual Reproduction

2 Cell Division “process where 1 cell splits into 2”
Replaces somatic (body) cells in multicellular organisms Allows for multicelullar growth Allows for asexual reproduction in plants

3 Chromosome – rod shaped structure made up
DNA and protein a. held together by centromere - holds chromatids together until they separate during division b. only found during cell division

4

5 Chromosome Number Human/animal chromosomes – sex chromosomes and autosomes Humans have 46 chromosomes in somatic cells Karyotype – used to examine an individual’s chromosomes

6

7 Haploid Diploid Reproductive cells (sperm and egg)
Somatic cells (body-all other cells) ½ the # of chromosomes (23) Has ALL chromosomes (46) half the DNA Has ALL DNA N = haploid 2N = diploid

8 Cell Division in Prokaryotes
Binary Fision – two identical cells are produced from one cell * division in bacteria

9 Cell Division in Eukaryotes
Mitosis Meiosis Asexual Reproduction Sexual Reproduction Division of diploid cells (somatic cells) Division of haploid cells (reproductive cells) Results in 2 identical daughter cells Results in 4 haploid daughter cells 1 division 2 divisions

10 Cell Cycle “series of events leading to cell division”
Interphase – occurs before mitosis begins - longest part of the cell cycle

11 Mitosis Asexual Reproduction
Diploid cells split into 2 identical diploid cells Allows body cells to be replaced and cells to GROW

12 Phases of Mitosis 1. Prophase Chromatin coils to make chromosomes
2 pairs of centrioles move apart and spindle fibers appear 2 types of spindle fibers a. kinetochore fibers b. polar fibers

13 2. Metaphase Kinetochore fibers move chromosomes to the center (equator) of the cell

14 3. Anaphase Spindle fibers grab the centromeres of each chromosome and pull the chromatids apart Chromatids now separate (now called daughter chromosomes) and are pulled to the opposite poles

15 4. Telophase Spindle fibers disassemble and chromosomes return to a less tightly coiled chromatin state Nuclear envelope and membrane reappear Cytokinesis – splitting of the cytoplasm a. cleavage furrow b. 2 cells are equal in size c. each cell receives an identical copy of the original cell’s chromosomes

16 Cytokinesis “division of the cytoplasm”
*animal cell – creates 2 new cells * Plant cell – forms cell plate

17 Meiosis “sexual reproduction”
Fusing of 2 haploid gametes to form 1 diploid zygote

18 Stages 2 divisions a. Meiosis I

19 b. Meiosis II

20 Sources of Genetic Variation
Crossing – over Fertilization Independent Assortment


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