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- 2. Mitosis • The process of cell division which results in the production of two daughter cells from a single parent cell. • The daughter cells are identical to one another and to the original parent cell. 2 https://www.nursingsathi.com
- 3. Mitosis can be divided into stages 1. Interphase 2. Prophase 3. Metaphase 4. Anaphase 5. Telophase 3 https://www.nursingsathi.com
- 4. Interphase The cell prepares for division DNA replicated Organelles replicated Cell increases in size 4 https://www.nursingsathi.com
- 5. Chromosomes become visible under LM Threads become shorter and thicker consist of two chromatids joined by centromere Nucleoli disappears Centrioles separates and migrate to each pole and starts giving out mitotic spindle Prophase The cell prepares for nuclear division 5 https://www.nursingsathi.com
- 6. Chromosomes line up at the center of the cell Spindle fibers attach from daughter cells to chromosomes at the centromere Equatorial plate is formed Microtubules of mitotic spindle are attached at centromere Microtubules exert pull on chromosomes Metaphase The cell prepares chromosomes for division 6 https://www.nursingsathi.com
- 7. Spindle fibers pull chromosomes apart ½ of each chromosome (called chromatid) moves to each daughter cell Chromatids separate and move to respective poles as an independent chromosome In human cell two identical sets of 46 chromosomes move to the opposite poles Anaphase The chromosomes divide 7 https://www.nursingsathi.com
- 8. A constriction called cleavage furrow appears in the middle of elongated cell Nuclear envelop is formed enclosing chromosomes 2 nuclei form Cell wall pinches in to form the 2 new daughter cells Telophase The cytoplasm divides 8 https://www.nursingsathi.com
- 10. Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase 10 https://www.nursingsathi.com
- 12. • Meiosis is the type of cell division by which germ cells (eggs and sperm) are produced. • One parent cell produces four daughter cells. • Daughter cells have half the number of chromosomes found in the original parent cell Meiosis 12 https://www.nursingsathi.com
- 13. During meiosis, DNA replicates once, but the nucleus divides twice. Four stages can be described for each division of the nucleus. Meiosis 13 https://www.nursingsathi.com
- 14. First division of meiosis 14 https://www.nursingsathi.com
- 15. Prophase is much longer consisting of five stages 1. Leptotene: Chromosomes becomes visible in the nucleus 2. Zygotene: Homologus chromosomes come together along their entire length and synapses are formed 3. Pachytene: Chromosomes become thicker and shorter Each chromosome pair is called bivalent 4. Diplotene: Chromosomes began to separate along their length. Each bivalent consists of four chromatids 5. Diakinesis: Separation of chromosomes continue. Nucleolus and the nuclear envelop disappears Prophase 15 https://www.nursingsathi.com
- 16. A spindle of microtubules is produced by centrioles Equatorial plate is formed The bivalent chromosome pairs align in the centre of the spindle Metaphase 16 https://www.nursingsathi.com
- 17. Chromosomes of homologous pairs completely separates and move to the opposite poles No division of centromere occurs and the whole chromosomes move to opposite poles Anaphase 17 https://www.nursingsathi.com
- 18. Nuclei are reconstructed The parent cell is divided in to two daughter cells Each daughter cell contains haploid (23) chromosomes Each chromosome is double structured consisting of two sister chromatids Telophase 18 https://www.nursingsathi.com
- 19. Second Division of Meiosis 19 https://www.nursingsathi.com
- 21. Differences in Mitosis & Meiosis Mitosis Asexual Cell divides once Two daughter cells Genetic information is identical Meiosis Sexual Cell divides twice Four haploid daughter cells Genetic information is different 21 https://www.nursingsathi.com