Cell Division All cells come from from pre-existing cells All cells come from from pre-existing cells New cells are produced for growth and to replace damaged or old cells New cells are produced for growth and to replace damaged or old cells Parent Cell Two identical daughter cells

Keeping Cells Identical The instructions for making cell parts are encoded in the DNA, so each new cell must get a complete set of the DNA molecules

DNA Replication- S phase DNA must be copied or replicated before cell division DNA must be copied or replicated before cell division Each new cell will then have an identical copy of the DNA Each new cell will then have an identical copy of the DNA Original DNA strand Two new, identical DNA strands

The Cell Cycle There are three phases of the Cell Cycle; 1.Interphase 2.Mitosis 3.Cytokinesis

Interphase Cell is doing its “Job” InterphaseCells spend most of their “life” in Interphase. DNA is in the form of Chromatin (spaghetti)

Chromatin DNA cannot be seen when cells aren’t dividing and is called chromatin. DNA cannot be seen when cells aren’t dividing and is called chromatin. During interphase the DNA is in the form of chromatin. During interphase the DNA is in the form of chromatin.

Interphase - G 1 Stage 1 st growth stage after cell division 1 st growth stage after cell division Cells mature by making more cytoplasm & organelles Cells mature by making more cytoplasm & organelles Cell carries on its normal cell activities (doing its “job”) Cell carries on its normal cell activities (doing its “job”)

Interphase – S Stage Synthesis stage Synthesis stage DNA is copied or replicated DNA is copied or replicated Two identical copies of DNA Original DNA

Interphase – G 2 Stage Cell prepares to divide. Cell prepares to divide. Occurs after DNA has been copied- checks the DNA for mistakes. Occurs after DNA has been copied- checks the DNA for mistakes. All cell structures needed for division are made (e.g. centrioles) and lots of ATP is made. All cell structures needed for division are made (e.g. centrioles) and lots of ATP is made.

After Interphase…Now the Cell is Ready for…MITOSIS

MITOSIS = Nuclear Division Prophase Metaphase Anaphase Telophase After Interphase…Now the Cell is Ready for….

Prophase is the first phase of Mitosis. *DNA in the form of Chromatin coils into Chromosomes *Nuclear Membrane Disappears *Centrioles move to Poles and spindle fibers form

Metaphase is the second phase of Mitosis. *Chromosomes line up in the MIDDLE of the cell *Spindle Fibers connect to Centromeres

Anaphase is the third phase of Mitosis APART *Chromosome copies are pulled APART at their Centromeres by the Spindle Fibers towards the poles

Telophase is the last (fourth) phase of Mitosis. *Nuclear Membrane re- forms around chromosomes *DNA uncoils back to Chromatin *Centrioles and Spindle Fibers Dissolve

Prophase is the first phase of Mitosis. *DNA in the form of Chromatin coils into Chromosomes *Nuclear Membrane Disappears *Centrioles move to Poles and spindle fibers form Metaphase is the second phase of Mitosis. *Chromosomes line up in the MIDDLE of the cell *Spindle Fibers connect to Centromeres Anaphase is the third phase of Mitosis. *Chromosome copies are pulled APART at their Centrometes by the Spindle Fibers towards the Poles Telophase is the last (fourth) phase of Mitosis. *Nuclear Membrane re- forms around chromosomes *DNA uncoils back to Chromatin *Centrioles and Spindle Fibers Dissolve Division of the Nucleus

Cytokinesis is the splitting of the Cell’s Cytoplasm and the last phase of the Cell Cycle (Overlaps with Telophase in Mitosis) In Animal Cells a Cleavage Furrow forms and pinches the cytoplasm apart. In Plant Cells a Cell Plate forms between the two new cells. Division of the Cytoplasm

Mitosis Animation Name each stage as you see it occur?

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Chromosomes All eukaryotic cells store genetic information in chromosomes All eukaryotic cells store genetic information in chromosomes Most eukaryotes have between 10 and 50 chromosomes in their body cells Most eukaryotes have between 10 and 50 chromosomes in their body cells Human body cells have 46 chromosomes or 23 identical pairs Human body cells have 46 chromosomes or 23 identical pairs

Chromosomes Each chromosome is composed of a single, tightly coiled DNA molecule Each chromosome is composed of a single, tightly coiled DNA molecule Chromosomes can’t be seen when cells aren’t dividing and are called chromatin Chromosomes can’t be seen when cells aren’t dividing and are called chromatin

Chromosomes in Dividing Cells Duplicated chromosomes are called chromatids & are held together by the centromere Called Sister Chromatids

Karyotype A picture of the chromosomes from a human cell arranged in pairs by size is called a Karyotype A picture of the chromosomes from a human cell arranged in pairs by size is called a Karyotype