Cell Reproduction PART 2: THE CELL CYCLE & MITOSIS

Objectives Describe the events of cell division in prokaryotes Describe the events of cell division in prokaryotes Name the two parts of the cell that are equally divided during cell division in eukaryotes Name the two parts of the cell that are equally divided during cell division in eukaryotes Summarize the events of interphase Summarize the events of interphase Describe the stage of mitosis Describe the stage of mitosis Compare cytokinesis in animal cells with cytokinesis in plants cells Compare cytokinesis in animal cells with cytokinesis in plants cells Explain how cell division is controlled Explain how cell division is controlled

Cell Division in Prokaryotes Facts about prokaryotes: They have cell _______. They lack a ________. Their DNA is a circular chromosome attached to the plasma membrane binary fission Their cell division is also called binary fission The prokaryotic chromosome is a single DNA molecule that first replicates, then attaches each copy to a different part of the cell membrane. When the cell begins to pull apart, the replicate and original chromosomes are separated. Following cell splitting, there are then two cells of identical genetic composition

Binary Fission in Bacteria

Cell Division in Eukaryotes Both the cytoplasm & the nucleus divide 2 types: _________: results in new cells with identical genetic material to the parent cell It occurs when organisms undergo growth, development, repair or asexual reproduction _________: reduces the chromosome number by half in new cells and occurs during the formation of gametes Mitosis Meiosis

The Cell Cycle Is the life pattern of a cell Is the life pattern of a cell It is highly ____________. It is highly ____________. It has 2 parts: It has 2 parts: Interphase Interphase Cell Division Cell Division

Control of Cell Division Is closely regulated in eukaryotic cells using checkpoints Is closely regulated in eukaryotic cells using checkpoints Checkpoints act like “traffic signals”, deciding when the cycle goes and when it stops Checkpoints act like “traffic signals”, deciding when the cycle goes and when it stops There are 3 checkpoints There are 3 checkpoints

Control of Cell Division When control is lost cancer resultsWhen control is lost cancer results Cancer cells are cell growth out of control!Cancer cells are cell growth out of control!

Interphase Is the time between cell divisions Cells spend the majority of their life cycle in interphase It is broken down into 3 phases: _______________

Interphase G 1 phase: when offspring cells grow to their mature size S phase: active DNA replication G 2 phase: prep time for cell division

The Cell Cycle Exceptions G 0 phase is an exit from the cell cycle These cells do not copy their DNA & do not prepare for cell division They are fully developed & cannot be re placed Ex. Nerve Cells

Cell Division Is divided into 2 phases ___________ ___________: the division of the cytoplasm Mitosis Cytokinesis

Review Name the phases of Interphase & describe what happens in each phase. G 1 phase: when offspring cells grow to their mature size S phase: active DNA replication G 2 phase: prep time for cell division

Mitosis Mitosis is the division of the cell nucleus. Mitosis is the division of the cell nucleus. Biologists divide the events of mitosis into 4 phases: Biologists divide the events of mitosis into 4 phases: 1.___________ 2.___________ 3.___________ 4.___________ Prophase Metaphase Anaphase Telophase

Prophase It begins with the DNA in the form of chromatin tightly coiling into ____________It begins with the DNA in the form of chromatin tightly coiling into ____________ The nucleolus & the nuclear membrane break down & disappearThe nucleolus & the nuclear membrane break down & disappear The centrosomes migrate to opposite poles of the cellThe centrosomes migrate to opposite poles of the cell In animal cells only, the centrosomes hold the ____________.In animal cells only, the centrosomes hold the ____________. Spindle fibers then begin to radiate from the centrosomesSpindle fibers then begin to radiate from the centrosomes

Prophase

Metaphase Meta = middle The chromosomes, which are made up of 2 sister ____________ connected by a _______________, line up in the middle of cell Spindle fibers attach to the kinetochores

Metaphase

Anaphase Ana = away, separate Ana = away, separate The chromatids of each chromosome separate at the centromere The chromatids of each chromosome separate at the centromere Then they are “reeled in’’ to opposite sides of the cell Then they are “reeled in’’ to opposite sides of the cell After this separation the chromatids are called individual chromosomes After this separation the chromatids are called individual chromosomes

Anaphase

Telophase After the individual chromosomes reach opposite ends of the cell, the ______ _______ disappear The ______________ reforms around each set of chromosomes The DNA returns to the less tightly coiled state of ____________

Telophase

Cytokinesis Is the division of the cytoplasm In plant cells, a cell plate forms between the two daughter cells. In animal cells, a cleavage furrow forms

Cytokinesis

Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Overview of Mitosis

Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Overview of Mitosis

Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Overview of Mitosis

Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Overview of Mitosis

Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Cytokinesis

Mitosis and Cytokinesis Can you identify the phases of mitosis in the onion? Can you identify the phases of mitosis in the onion?