Meiosis - The Cell Cycle PDF

Meiosis General Biology 1 Prepared By: Vender Saddul, LPt, MMin Agenda for Today 1. Routine 2. Review of previous lessons 3. Motivations 4. Teacher-led discussion 5. Group activity 6. Values integration 7. Reminders  Lecture is based on your textbook, Chapter 4, pages 102-...

Meiosis General Biology 1 Prepared By: Vender Saddul, LPt, MMin Agenda for Today 1. Routine 2. Review of previous lessons 3. Motivations 4. Teacher-led discussion 5. Group activity 6. Values integration 7. Reminders  Lecture is based on your textbook, Chapter 4, pages 102- 127 Review of Previous Lesson  Why do cells divide? 1. Ensures persistence of genome Precisely replicates DNA Equally distributes DNA to opposite end of cell Seperates into two identical daughter cells Genome = total endowment of DNA unique to each species  Why do cells divide? 2. Strategy to counter loss of SA:Vol ratio as cell grows larger  Why do cells divide? 3. For growth, development, and repair Cell division in eukaryotes Chromosomes consist of a DNA- protein complex called chromatin. Proteins include histones that aid in coiling of nucleic material in dense, visible chromatids Mitosis duplicates chromosones to pairs of sister chromatids (duplication is very precise: only 1 error in 100,000) and sends each replication to opposite poles of the cell Mitosis may be followed by cytokinesis  The cell cycle Interphase 90% of time spent in Interphase S-phase G1 = first growth phrase S = duplication of DNA G2 = second growth phase G1 G2 10% in dividing, or M phase Mitosis - division of nucleus Cytokinesis Mitosis M-phase Chromosome Structure (page 79) 4 Phases of Mitosis Mitosis is composed of five phases 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase During each phase, different proteins in the cell perform specific roles to divide the two copies of genetic material Cytokinesis occurs after mitosis to create two cells Mitosis in an Onion Root Tip Cytokinesis  Cell Cycle Checkpoints: Ensuring Safe Division The cell cycle is tightly regulated by checkpoints that ensure each phase is completed accurately before moving on to the next step. Failures in these checkpoints can lead to diseases such as cancer.  The G1 Checkpoint Ensures the cell is ready to enter the S phase (DNA synthesis). Checks for: Cell size Nutrient availability Growth factors (signals from other cells) DNA damage If the cell does not meet the criteria: It may enter a resting state called G0 or undergo repair mechanisms.  The G2 Checkpoint Preparing for Mitosis Ensures the cell is ready to divide (enter mitosis). Checks for: cell size Complete DNA replication DNA integrity (checks for damage or replication errors) If issues are detected: The cell cycle is paused to repair DNA, or the cell undergoes apoptosis if the damage is irreparable.  The Metaphase Checkpoint Spindle Assembly Checkpoint – Ensuring Proper Division Ensures proper chromosome alignment and attachment to the mitotic spindle during metaphase of mitosis. Checks for: Proper attachment of chromosomes to spindle fibers at the centromeres. Correct alignment of chromosomes at the metaphase plate. If issues arise: The cell delays anaphase to prevent unequal distribution of chromosomes, which could lead to genetic disorders. How is Meiosis different from Mitosis? Purpose Mitosis: For growth, repair, and asexual reproduction. Meiosis: For sexual reproduction, producing gametes (sperm and egg cells). Number of Divisions Mitosis: Involves one division, producing two daughter cells. Meiosis: Involves two divisions, producing four daughter cells. Daughter Cells Mitosis: Results in two genetically identical diploid cells (same number of chromosomes as the parent cell). Meiosis: Results in four genetically unique haploid cells (half the number of chromosomes of the parent cell). Daughter Cells Mitosis: Results in two genetically identical diploid cells (same number of chromosomes as the parent cell). Meiosis: Results in four genetically unique haploid cells (half the number of chromosomes of the parent cell). Homework: Create a table that highlights the key differences between Mitosis and Meiosis. Write your answers neatly in your notebook. Mark the start of the 2nd quarter by clearly labeling this section in your notebook Key Differences Mitosis Meiosis Purpose number of chromosomes Genetic variation number of division daughter cells Reminders about Outputs  Homework: Passive transport Submission of Outputs Saddul, Vender I. Tower of David Oct 15 For all outputs always write your names on the front page, upper left corner. Write your surnames first, followed by your given name and middle initial Below your name write your section. Do not abbreviate your section name. Saddul, Vender I. Below your section, write the date. Be Tower of David Oct 15 sure to write the month in letters, not in numbers. Below your section, write the date. Be sure to write the month in letters, not in numbers.  Homework: Passive transport Submission of Outputs Saddul, Vender I. Tower of David Oct 15 Always include a title: Quiz 1 Asynchcronous Activity: Cell theory Video Reaction: Mitosis Reflection on Careers in Biologyy Seatwork: biomolecules (protein) Workbook activity: Concept map Lab Activity: Cell cycle Solo Minor PT: Cell simulation Saddul, Vender I. Tower of David Oct 15 Leave a space between activities in your notebook. Avoid Homework: Passive transport crowding the page to keep it neat and organized.  Homework: Passive transport Submission of Outputs Saddul, Vender I. Tower of David Use black pen ONLY for the main text of your output. But you are allowed to use other pen color for highlights, titles and subtiles. Keep your work neat. Even if neatness isn't part of the rubric, messy outputs will still result in deductions. If erasures are unavoidable, make sure they are done neatly to maintain a clean presentation.  Title: The Cell Cycle Submission of Outputs Saddul, Vender I. Tower of David For word-processed outputs, please 1. Introduction ensure to follow these guidelines: 1.1 Definition of the cell cycle 1.2 Importance in growth and repair Use Arial or Times New Roman as the font style, with a font size of 12. 2. Phases of the Cell Cycle 2.1 Interphase Include clear titles and subtitles for 2.1.1 G1 phase: Cell growth 2.1.2 S phase: DNA replication better readability, and make them 2.1.3 G2 phase: Preparation bold for emphasis. 2.2 Mitosis 2.2.1 Prophase Use proper indentation in paragraphs. 2.2.2 Metaphase For numbering, use plain numbers 2.2.3Anaphase, Telophase rather than Roman numerals or letters. 3. Conclusion 3.1 Summary of the stages 3.2 Significance of each phase Submission of Outputs When submitting your outputs in Canvas or MS Teams, it is recommended that you convert your files to PDF. This helps prevent any formatting issues or changes that might occur when the file is opened in different applications like Microsoft Word, WPS, or others. Name/rename your file using the following format: surname, initial_SECTION_activity Example: Saddul VI_DAVID_PT biomolecules Meiosis Videos https://www.youtube.com/watch?v=63hFfJOJg9w https://www.youtube.com/watch?v=sff8dBkvg9s https://www.youtube.com/watch?v=QtCjQYosj_g&t=78s https://www.youtube.com/watch?v=fK-Q6WEnEqw  Cell Division videos http://www.youtube.com/watch?v=VlN7K1-9QB0 http://www.youtube.com/watch?v=CzPGhYiGyZ8&feature=related Embryonic division in the worm c.elegans: http://www.youtube.com/watch?v=zsgOl04PESI&NR=1 http://www.cellsalive.com/mitosis.htm