BE101 Lecture 7 Cell Division PDF

Different Types of Cell Division With Anne Leung Cell Division in Prokaryotes: Binary Fission Binary fission is a type of asexual reproduction typically observed in prokaryotes and a few single-celled eukaryotes. Binary Fission Prokaryotic cells (eg. bacteria) divide by binary fission....

Different Types of Cell Division With Anne Leung Cell Division in Prokaryotes: Binary Fission Binary fission is a type of asexual reproduction typically observed in prokaryotes and a few single-celled eukaryotes. Binary Fission Prokaryotic cells (eg. bacteria) divide by binary fission. Form of asexual reproduction in which a parent cell divides to form two identical daughter cells. Occasionally, a mistake can arise in DNA replication so daughter cells are different → mutation.  Cell Division in Eukaryotes: Interphase, Mitosis and Cytokinesis The process by which a single cell becomes two identical daughter cells. In Eukaryotes, mitosis is for growth and repair.  Cell Cycle (Eukaryotes) Cell division in eukaryotes proceeds through a number of steps that make up the cell cycle. The cell cycle consists of two distinct stages: Interphase: the time between two successive M phases Mitotic (M) phase: the time during which the parent cell divides into two daughter cells  Interphase Interphase is the phase of the cell cycle in which a typical cell spends most of its life. During this stage, the cell makes many preparations for division. These preparations include an increase in the cell size so that each daughter cell receives sufficient amounts of cytoplasmic and membrane components, and the replication of the DNA in the nucleus. Phases: 1. G1 phase 2. S phase 3. G2 phase 4. G0 phase Cell Division Chromosomes replicate during the S phase (Synthesis phase) of interphase so chromosome number can be the same in parent & daughter cell (2n → 2n).  Mitosis phases Prophase Metaphase Prometaphase Anaphase Telophase Prophase Prometaphase Metaphase Anaphase Telophase  (Animal) Cytokinesis Mitosis result in two separate nuclei contained within a single cell. Cytokinesis performs an essential process to separate the cell in half and ensure that one nucleus ends up in each daughter cell. Cytokinesis (Plant)  Importance of the M phase Phase Description Prophase Chromatin condenses into visible chromosomes, the nuclear envelope breaks down, and the mitotic spindle forms Prometaphase The chromosomes attach to the spindle fibers and begin to move towards the center of the cell Metaphase The chromosomes align at the equator of the cell, forming the metaphase plate Anaphase The sister chromatids separate and move towards opposite poles of the cell Telophase The chromosomes reach the poles of the cell, the nuclear envelope reforms, and the chromosomes begin to decondense Cytokinesis The cytoplasm divides, resulting in two daughter cells with identical genetic material  Mitosis importance Multicellular Genetic organisms integrity Essential process for life Prevents Organs mutation maintenance  Mitosis Link to short video for visual learners: https://youtu.be/NwwcWqL5hhI?feat ure=shared Meiotic Cell Division (Meiosis) Cell division in sexually reproducing organisms  What does meiosis do? Results in four daughter cells. Each daughter cell contains half the number of chromosomes as the parent. Each daughter cell is genetically unique. Meiosis Meiotic cell division consists of two cell divisions called meiosis I and meiosis II.  < Meiosis I Meiosis I : Prophase I Chiasmata Tetrads MEIOSIS I Meiosis II < Meiosis II is all about splitting the duplicated chromosomes into single chromosomes in the newly formed cells. Meiosis II is very similar to mitosis but with half the number of chromosomes, and it’s the final step that leads to the formation of sperm or egg cells. These cells are called gametes. Meiosis II  MEIOSIS SUMMARY Important for genetic diversity Reduces the chromosome number by half during formation of gametes in animals and spores in plants (sex cells). The first (Meiosis I) is a reductive division where chromosomal pairs are separated ⇒ a diploid parent cell (2n) results in 2 haploid (n) cells. The second division (Meiosis II) separates the chromatid pairs ⇒ 4 daughter cells with (n) chromosomes When 2 gametes fuse together ⇒ new cell (zygote) will always be diploid (2n) (n) (n) (2n) Diploid zygote (2n) (n) (n) (n) (n) Diploid parent (n) (n) Diploid parent (2n) Haploid daughter Haploid daughter  Meiosis Link to short video: https://youtu.be/kQu6Yfrr6j0?featur e=shared  Abnormal cell division Abnormal Cancer cell division Chromosome abnormalities Developmental disorders Neurodegenerative diseases  Thanks! Do you have any questions? CREDITS: This presentation template was created by Slidesgo, and includes icons by Flaticon, and infographics & images by Freepik