Cell Division How do we get new cells and new living things?
Mitosis Mitosis, the process by which the body grows and replaces cells, is divided into five phases. Meiosis Meiosis occurs during the formation of gametes in animals. Cell Division
Prophase Interphase Anaphase Mitosis Overview Telophase Metaphase Interphase
Interphase • G1 phase- Cell growth • S phase- DNA Replication • G2 phase- Preparation for mitosis • This is the longest phase of all
Prophase • Nucleus Condenses • DNA is compacted into movable packages called Chromosomes
Metaphase • Aligning chromosomes at cell equator • Attaching spindle fibers from each new daughter cell pole to each chromosome at the centromere
Anaphase • Spindle fibers pull chromosomes apart • Half of the chromosomes (chromatid) moves to a new daughter cell
Telophase & Cytokinesis • DNA gathers and two nuclei form • new cell wall and membrane appears between the two nuclei to form two new daughter cells and cytoplasm pinches in half Cell Plate
Interphase • From new cell formation into rest phase again
Meiosis Gamete Formation and Recombination
cell division that produces reproductive cells in sexually reproducing organisms; the nucleus divides into four nuclei each containing half the chromosome number leading to gametes. Meiosis Definition
Division 1 • Interphase 1: DNA replication • Prophase 1: Each chromosome forms and remains closely associated. These are called sister chromatids. • Metaphase 1: Homologous chromosomes align at the equatorial plate. • Anaphase 1: Homologous pairs separate with sister chromatids remaining together. • Telophase 1: Two daughter cells are formed with each daughter containing only one chromosome of the homologous pair.
Division 2 • Prophase 2: DNA does not replicate. • Metaphase 2: Chromosomes align at the equatorial plate. • Anaphase 2: Centromeres divide and sister chromatids migrate separately to each pole. • Telophase 2: Cell division is complete. Four haploid daughter cells are obtained.
Web Link to animated Meiosis http://www.sumanasinc.com/webcontent/anisamples/majorsbiology/meiosis.html
Who can Explain Each Step? Step 4 Step 3 Step 1 Step 2