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Download Bio392-Chapter 10-2 - Cell Division- this one!!
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Friday Feb 10th Day E • Collect remaining Wequests • Begin 10.2 – Notes – Video Clip – Handout HW – Study for 10.1 Quiz Chapter 10 Vocabulary Surface area/volume problems Chapter 10.2 Cell Division Cell Division • Before a cell gets too large, a growing cell divides forming two “daughter cells” • Cell division process by which a cell divides into two new daughter cells • Before cell division begins, DNA replicates (copies) itself One copy for each new cell Division in Prokaryotes • After DNA is copied, cell splits in two Each new cell contains a copy of the DNA called binary fission – Example of asexual reproduction Binary Fission in a Paramecium Division in Eukaryotes • Occurs in two main stages – 1st stage division of the nucleus = mitosis – 2nd stage division of the cytoplasm = cytokinesis • Helps multicellular organisms grow and develop Chromosomes • Structures that carry genetic information – Made up of DNA and protein (histones) • Humans have 46 total (23 pairs) (other organisms have different numbers) Chromosomes • While the cell is “resting”, you cannot see the chromosomes. It is unwound Called chromatin (1) Double-stranded DNA. (2) Chromatin strand (DNA with histones). (3) Chromatin during interphase with centromere. (4) Condensed chromatin during prophase. (Two copies of the DNA molecule are now present) (5) Chromosome chromosome during metaphase. chromatin Chromosomes • While the cell is dividing, you can see the chromosomes It is wound up Made of two sister chromatids connected by a centromere Chromosomes Sister Chromatid Centromere The Cell Cycle • Occurs in eukaryotic cells G1 phase It is the period of time from the beginning of one cell M phase division to the beginning of the next S phase G2 phase • Cell doubles its contents so that it is ready to divide into two completely independent cells The Cell Cycle G1 phase M phase S phase G2 phase Consists of 4 phases – 1. M phase – mitosis the division of the cell nucleus and cytokinesis – 2. G1 intense growth and activity; new proteins and organelles are made – 3. S phase copying of chromosomes – 4. G2 intense growth and activity; new proteins and organelles are made • Shortest of the four phases M phase • Cell division – Process in which the cell divides into two independent cells daughter cells – Process is called mitosis in eukaryotes and binary fission in prokaryotes Cell Cycle Rates Cells do not move through the cell cycle at the same rate – Average rate of a human cell is once every 20 hours Mitosis • Time of cell division • Divided into four main phases – 1. Prophase – 2. Metaphase – 3. Anaphase – 4. Telophase Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase 1. Prophase • 1. Appearance of chromosomes – 2 sister chromatids attached at the centromere Spindle forming • 2. Nuclear membrane begins to breakdown • 3. Spindle begins to form – Purpose is to pull chromatids apart Centromere • 4. Spindle attaches to the chromosomes at the centromere – In animals, spindle is made by the centriole Plants lack centrioles Chromosomes (paired chromatids) 2. Metaphase • 1. Chromosomes line up in the middle of the cell Centriole Spindle Centriole 3. Anaphase • 1. Centromeres split • 2. Sister chromatids are pulled to the opposite ends of the cell by the spindle Individual chromosomes 4. Telophase • 1. Spindle breaks down • 2. Nuclear envelope reforms around the chromosomes • 3. Chromosomes unwind to chromatin again Nuclear envelope reforming Cytokinesis • Division of the cytoplasm • In animals the cell pinches in at the middle to create two new cells • In plants a cell plate is created in the middle of the cell Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Videos • Animal Cell Mitosis • Animal Cell Cytokinesis • Animal Cell Mitosis: Interactive • How the Cell Cycle Works Friday Feb 10th Day E • Collect remaining Wequests • Begin 10.2 – Notes – Video Clip – Handout HW – Study for 10.1 Quiz Chapter 10 Vocabulary Surface area/volume problems
