Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 1.3 Cells from cells
Transcript
1.3 CELLS FROM CELLS Learning Objectives: To understand the stages of cell reproduction. Keywords: Cell division Mitosis Cytokinesis DNA replication Prophase Metaphase Anaphase Telophase Cell plate Let’s Watch a Video https://www.youtube.com/watch?v=L0k-enzoeOM Mitosis The process by which the duplicated contents of the cell’s nucleus divide into two equal parts. The Phases of Mitosis ■ Prophase ■ Metaphase ■ Anaphase ■ Telophase Prophase Chromosome pair up! Chromosomes thicken and shorten -become visible -2 chromatids joined by a centromere 2. Centrioles move to the opposite sides of the nucleus 3. Nucleolus disappears 4. Nuclear membrane disintegrate ■ 1. Metaphase ■ Chromosomes meet in the middle! 1. Chromosomes arrange at equator of cell 2. Become attached to spindle fibres by centromeres 3. Homologous chromosomes do not associate Anaphase ■ Chromosomes get pulled apart 1. Spindle fibres contract pulling chromatids to the opposite poles of the cell Telophase ■ Now there are two! 1. Chromosomes uncoil 2. Spindle fibres disintegrate 3. Centrioles replicate 4. Nucleur membrane forms 5. Cell divides TASK Using the materials provided, make a 3D model of the phase of mitosis assigned to you. 15 minutes What is Cytokinesis ■ This is the last stage of the cell cycle & it completes the process of cell division ■ During Cytokinesis the cytoplasm divides ■ Organelles are distributed into each of the new cells ■ When cytokinesis is complete two new cells (daughter cells) have formed At the end of cytokinesis each cell enters interphase and the cell cycle begins. The cell cycle: Cytokinesis in animal cells ■ During cytokinesis in animal cells the cell membrane squeezes together around the middle of the cell. ■ The cytoplasm forms into two cells. ■ Each daughter cell gets about 1/2 of the organelles. Cytokinesis in plant cells ■ Because the plant cell has a cell wall unlike the animal cell, it can’t squeeze together like the cell membrane can. ■ Instead a structure called the cell plate forms across the middle of the cell and the cell gradually splits into two cells. ■ Then two new cell wall forms Cytokinesis in a plant cell Can you spot the Cell plate?? Cytokinesis in a animal cell. The arrow’s point out the cell membrane seperating Cytokinesis In Animal And Plant Cells 100 µm Cleavage furrow Contractile ring of microfilaments Vesicles forming cell plate Wall of patent cell 1 µm Cell plate New cell wall Daughter cells Daughter cells (a) Cleavage of an animal cell (SEM) (b) Cell plate formation in a plant cell (SEM)
