Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Mitosis Interphase (Technically not part of mitosis, but it is included in the cell cycle) Cell is in a resting phase, performing cell functions DNA replicates (copies) Organelles double in number, to prepare for division G1 - First growth S - Synthesis (copy DNA) G2 - Second growth Prophase Spindle forms Centrioles move to opposite poles Chromosomes become visible Nuclear membrane breaks down in prometaphase Metaphase Chromosomes line up along the equator Anaphase Centromeres divide Chromatids separate and move to opposite poles Telophase Nuclear membrane forms around each group of chromosomes Chromosomes unwind Cytokinesis begins - cell pinches inward and forms two daughter cells. Meiosis The process of nuclear division where the number of the chromosomes is halved. produces four daughter cells all daughter cells are haploid chromosomes are shuffled in the process, so that each daughter cell has a unique combination used to create gametes (sperm and egg) Prophase 1 homologous chromosomes pair up (tetrad) crossing-over occurs Crossing Over - chromosomes exchange sections (increases variability) Independent Assortment In addition to Crossing-Over, the process of meiosis ensures that chromosomes are randomly assorted. The following images show three separate possibility for a single cell that has undergone meiosis. Look at all the different combinations. Sexual Reproduction - Involves the fusion of gametes, creates unique offspring - Eggs are much larger than sperm Image of egg and sperm *Polar bodies are nonfunctioning cells Asexual Reproduction --Does not involve the fusion of gametes --Offspring are identical to parents