Mitosis and Meiosis: Understanding Cell Division

This presentation provides a clear overview of mitosis and meiosis, the two key processes of cell division. It covers the stages of each process, highlights their differences, and explains their roles in growth, repair, and reproduction. Visual aids and comparisons help illustrate the importance of these mechanisms in maintaining life and promoting genetic diversity.

1. Mitosis and meiosis Understanding cell division and onion root tip experiment by sanuj pandey

2. INTRODUCTION Overview of cell division Important of cell division Types of cell division

3. Imp of mitosis What is mitosis? Mitosis is a type of cell division that results in two genetically identical daughter cells from a single parent cell. It's a crucial process for growth, repair, and asexual reproduction in eukaryotic organisms. Role in growth and repair Growth: Mitosis increases cell numbers, helping organisms grow by generating more cells. Repair: Mitosis replaces damaged or dead cells, allowing tissues to heal and regenerate.

4. Stage of mitosis Prophase : The chromatin condenses into visible chromosomes, and the nuclear envelope begins to break down. The mitotic spindle, made of microtubules, starts to form. Metaphase : Chromosomes align along the cell's equatorial plane, known as the metaphase plate. The spindle fibers attach to the centromeres of the chromosomes. Anaphase : The centromeres split, and the spindle fibers pull the sister chromatids (now individual chromosomes) towards opposite poles of the cell. Telophase : Chromosomes reach the poles and begin to de-condense back into chromatin. The nuclear envelope reforms around each set of chromosomes, resulting in two distinct nuclei within the cell. Cytokinesis : This is the final step where the cytoplasm of the cell divides, resulting in two separate daughter cells, each with its own nucleus and complete set of organelles.

5. meiosis What is meiosis? Meiosis is a type of cell division that reduces the chromosome number by half, creating four genetically diverse daughter cells. Role in sexual reproduction Produces Gametes : Creates haploid sperm and eggs with half the chromosome number of the parent cells . Generates Genetic Variation : Introduces diversity through crossing over and independent assortment . Reduces Chromosome Number : Ensures that gametes have half the number of chromosomes, so the zygote will have the correct diploid number after fertilization . Ensures Proper Chromosome Number : Maintains the species-specific chromosome number in offspring.

6. Meiosis one and two Prophase : The chromatin condenses into visible chromosomes, and the nuclear envelope begins to break down. The mitotic spindle, made of microtubules, starts to form. Metaphase : Chromosomes align along the cell's equatorial plane, known as the metaphase plate. The spindle fibers attach to the centromeres of the chromosomes. Anaphase : The centromeres split, and the spindle fibers pull the sister chromatids (now individual chromosomes) towards opposite poles of the cell. Telophase : Chromosomes reach the poles and begin to de-condense back into chromatin. The nuclear envelope reforms around each set of chromosomes, resulting in two distinct nuclei within the cell. Cytokinesis : This is the final step where the cytoplasm of the cell divides, resulting in two separate daughter cells, each with its own nucleus and complete set of organelles.

7. Comparison of mitosis and meiosis Mitosis Divisions : One Daughter Cells : Two (diploid ) Genetic Variation : None Function : Growth, repair, asexual reproduction Meiosis Divisions : two Daughter Cells : Four ( haploid) Genetic Variation : High (through crossing over and independent assortment) Function : Production of gametes for sexual reproduction

8. Onion root tip experiment- mitosis Objective: understanding mitosis through onion root tips. Material and method: onion root tips, microscope, stains,etc .

9. Steps to prepare and observe the expirement . Collect Root Tips : Cut 1-2 mm tips from onion roots . Fixation : Immerse root tips in fixative solution for 10-15 minutes . Staining : Place in a staining solution (e.g., acetic orcein ) for 5-10 minutes . Prepare Slide : Place root tip on a slide, add a few drops of water or mounting medium, and gently squash with a cover slip . Observe : Examine under a microscope to identify stages of mitosis . Record : Note observations and clean up.

10. By sanuj pandey