Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

Cell Life Cycle Cells have 2 major phases: 1. Interphase  Cell grows  metabolic processes  DNA replication 2. Cell division (Mitosis)  Cell replicates itself  Function -- produce more cells for growth and repair processes

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings #1. How many chromosomes are in each human body cell?

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Events of Cell Division  Mitosis—division of the nucleus  two daughter nuclei  Cytokinesis—division of cytoplasm  two daughter cells *Predict the outcome if: Mitosis occurred but NOT Cytokinesis. What about if Cytokinesis occurred but NOT Mitosis? Longest phase !!

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings #2. A cell has 40 chromosomes completes the cell cycle. What would be the result? a.1 cell of 40 chromosomes b.2 cells of 40 chromosomes each c.1 cell of 80 chromosomes d.2 cells of 20 chromosomes each

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Mitosis 1. Prophase – 1 st phase  Centrioles migrate to poles  DNA appears as double-stranded chromosomes  Nuclear envelope breaks down and disappears

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Mitosis 2. Metaphase  Chromosomes in CENTER of the cell Metaphase Sister chromatids Spindle Metaphase plate

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Mitosis 3. Anaphase  Chromosomes pulled apart; toward opposite ends of the cell  Cell elongates

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Mitosis 4. Telophase  Chromosomes uncoil  Nuclear envelope reforms  Spindles break down and disappear

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Mitosis 4 (a). Cytokinesis  Begins during late anaphase & completes during telophase  Cleavage furrow forms to pinch cells into 2 parts

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings #3. What is the correct order of the cell cycle? a. metaphase  interphase  anaphase  telophase  prophase b. anaphase  telophase  prophase  metaphase  interphase c. interphase  prophase  metaphase  anaphase  telophase d. telophase  anaphase  interphase  metaphase  prophase

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Mitosis Figure 3.15, step 7 Centrioles Plasma membrane Interphase Early prophase Late prophase Nucleolus Nuclear envelope Spindle pole Chromatin Centrioles Forming mitotic spindle Centromere Chromosome, consisting of two sister chromatids Fragments of nuclear envelope Centromere Spindle microtubules Metaphase Anaphase Telophase and cytokinesis Daughter chromosomes Sister chromatids Nuclear envelope forming Nucleolus forming Spindle Metaphase plate Cleavage furrow