Cell Division

Biology : ว 31141 Cell division

Cell Cycle

Keyword in this unit Mitosis Metaphase Synthesis Meiosis Anaphase Resting stage Interphase Telophase Spindle fiber Prophase Chromatid Karyotype

Cell Division Mitosis Meiosis The cells The cells created from created from mitosis are meiosis are diploid or 2n haploid or n 4

Mitosis ➢Some haploid & diploid cells divide by mitosis. ➢Each new cell receives one copy of every chromosome that was present in the original cell. ➢Produces 2 new cells that are both genetically identical same as the original cell.

Mitosis Interphase Prophase Metaphase Anaphase Telophase

Interphase • G1 - Cells undergo majority of growth • S - Each chromosome replicates (Synthesis) to produce sister chromatids – Attached at centromere – Contains attachment site (kinetochore) • G2 - Chromosomes condense - Assemble machinery for division such as centrioles

What’s Happening in Interphase? Animal Cell What’s occurring 8

Prophase

Early Prophase ✓ Chromatin in nucleus condenses to form visible chromosomes ✓ Mitotic spindle forms from fibers in cytoskeleton or centrioles (animal) Nucleolus Cytoplasm Chromosomes Nuclear Membrane 10

Late Prophase ✓Nuclear membrane & nucleolus are broken down ✓Chromosomes continue condensing & are clearly visible ✓Spindle fibers called kinetochores attach to the centromere of each chromosome ✓Spindle finishes forming between the poles of the cell 11

Review of Prophase 12

Metaphase

Metaphase ✓Chromosomes, attached to the kinetochore fibers, move to the center of the cell ✓Chromosomes are now lined up at the equator Equator of Cell Pole of the Cell 14

Metaphase Asters at the poles Spindle Fibers Chromosomes lined at the Equator 15

Metaphase Aster Chromosomes at Equator 16

Review of Metaphase What’s occurring 17

Anaphase

Anaphase ✓Occurs rapidly ✓Sister chromatids are pulled apart to opposite poles of the cell by kinetochore fibers

Anaphase Sister Chromatids being separated 20

Anaphase Review What’s occurrin g

Telophase

Telophase ✓Sister chromatids at opposite poles ✓Spindle disassembles ✓Nuclear envelope forms around each set of sister chromatids ✓Nucleolus reappears ✓CYTOKINESIS occurs ✓Chromosomes reappear as chromatin

Comparison of Anaphase & Telophase 24

Cytokinesis ✓Means division of the cytoplasm ✓Division of cell into two, identical halves called daughter cells ✓In plant cells, cell plate forms at the equator to divide cell ✓In animal cells, cleavage furrow forms to split cell

Cytokinesis Cleavage furrow in Cell plate in plant cell animal cell 26

Mitosis Quiz 27

Mitosis Quiz

Name the Stages of Mitosis: Early Anaphase Early prophase Metaphase Interphase Early Telophase, Begin cytokinesis Late Late telophase, Mid-Prophase Late Anaphas Prophase Advanced 29 cytokinesis

Identify the Stages ? Early, Middle, & Late Prophase ? ?? Late Prophase Metaphase Anaphase ? ?? Late Anaphase Telophase Telophase&Cytokinesis

Locate the Four Mitotic Stages in Plants Anaphase Telophase Metaphase Prophase 31