Cell Cycle and Mitosis Prokaryotes bacteria Eukaryotes plants

Cell Cycle and Mitosis ØProkaryotes Ø bacteria Ø Eukaryotes Ø plants Ø animals

Prokaryotes Ø Lack a nucleus Ø Have a single chromosome Ø Reproduce by binary fission Ø Include bacteria

Steps in Binary Fission Used by bacteria Ø Cells increase their cell mass slightly Ø DNA & cell components are replicated Ø Each cell divides into 2 daughter cells

Binary Fission of Bacterial Cell

E. Coli Dividing by Binary Fission

Eukaryotes Ø Contain a nucleus & membrane bound organelles Ø Asexually reproduce cells by mitosis

Cell Cycle Stages in growth & division Ø Interphase Ø G 1 Phase Ø S Phase Ø G 2 Phase Ø M Phase Ø Cytokinesis

G 1 Phase Ø First growth stage Ø Cell increases in size Ø Cell prepares to copy its DNA

Synthesis Phase Ø Copying of all of DNA’s instructions Ø Chromosomes duplicated

G 2 Phase Ø Time between DNA synthesis & mitosis Ø Cell continues growing Ø Needed proteins produced

M Phase Ø Cell growth & protein production stop Ø Cell’s energy used to make 2 daughter cells Ø Called mitosis or karyokinesis (nuclear division)

Interphase – Resting Stage Ø Includes G 1, S, and G 2 Ø Cells carrying on normal activities Ø Chromosomes are not visible Ø Cell metabolism is occurring Ø Occurs before mitosis copyright cmassengale

Interphase

Stages of Mitosis Ø Prophase Ø Metaphase Ø Anaphase Ø Telophase

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Cells Undergoing Mitosis

Steps in Prophase Ø DNA coils tightly & becomes visible as chromosomes Ø Nuclear membrane disappears Ø Nucleolus disappears Ø Centrioles migrate to poles Ø Spindle begins to form

Prophase

Eukaryotic Chromosome

Human Chromosomes

Steps in Metaphase Ø Spindle fibers from centrioles attach to each chromosome Ø Cell preparing to separate its chromosomes Ø Cell aligns its chromosomes in the middle of the cell

Metaphase

Steps in Anaphase Ø Cell chromosomes are separated Ø Spindle fibers shorten so chromosomes pulled to ends of cell

Mitotic Spindle

Anaphase

Steps in Telophase Ø Separation of chromosomes completed Ø Cell Plate forms (plants) Ø Cleavage furrow forms(animals) Ø Nucleus & nucleolus reform Ø Chromosomes uncoil

Telophase

Telophase Plant Animal

Cytokinesis Occurs after chromosomes separate Ø Forms two, identical daughter cells Ø

Cytokinesis

Cytokinesis Cell Plate Forming in Plant Cells