Cell Cycle & Mitosis

What is the Cell Cycle? All of the steps of a cells life! There are two basic parts of the cell cycle: Interphase A period of growth between divisions. Cell Division Mitosis Cytokinesis

What are the phases of the Cell Cycle? Interphase: A period of growth between divisions. G1 Phase – Time when cell grows to full size S Phase – Time when cell replicates DNA G2 Phase – Time when cell duplicates its organelles G0 Phase – Time when cell leaves cell cycle (not all cells do this. Example: Nerves)

Phases Continued M – Phase (Mitosis) – Nuclear Division, the cell divides its chromosomes between two cells Cytokinesis – the cytoplasm actually divides to make two new cells.

Fill Out the Pie! Start at the Star! (M) Mitosis – Nuclear Division (C) Cytokinesis – Cytoplasm Divides = Interphase – Period of growth between divisions (Cell spends 90% of its time in interphase) M C G2 Phase G1 Phase Cell Duplicates organelles S Phase DNA Replicates Cell starts initial growth Start at the Star! G0 Phase Cell Doesn’t Divide

Mitosis Prophase Metaphase Anaphase Telophase

Review the Cell Cycle! Interphase: A period of growth between divisions. G1 Phase – Time when cell grows to full size S Phase – Time when cell replicates DNA G2 Phase – Time when cell duplicates its organelles G0 Phase – Time when cell leaves cell cycle (not all cells do this. Example: Nerves) M – Phase (Mitosis) – Nuclear Division, the cell divides its chromosomes between two cells Cytokinesis – the cytoplasm actually divides to make two new cells.

Mitosis What is Mitosis? Why does mitosis happen? Nuclear Division, the cell divides its chromosomes between two cells Why does mitosis happen? So that each daughter cell has exactly the same DNA as the parent cell. How long does it take for mitosis to happen? 10% of a cell’s life cycle (so it depends on the cell type.)

How does mitosis Happen? Prophase – The “Prepare” Phase Nucleus Vanishes Spindle Sets Up Spindle Moves the chromosomes around Chromosomes form Centrioles Nucleus Vanishing Chromosomes Winding

What is a Chromosome? A chromosome is a piece of DNA that is tightly wound around proteins. What does a chromosome look like? A eukaryotic chromosome (like yours) is X shaped. A prokaryotic chromosome (like bacteria) is a loop.

Chromosome Parts S I T E R CH OM A D Sister chromatids – the identical “legs” of the chromosome Centromere – holds the sister chromatids together. Centromere

How does mitosis happen? Metaphase – The “Middle” Phase Chromosomes line up in the middle of the cell. spindle Chromosome

How does mitosis happen? Anaphase – the “Away” Phase Sister Chromatids move away from each other to opposite sides of the cell. Spindle Sister Chromatid

How does mitosis happen? Telophase – “The End” Phase Nucleus reappears Spindle Disassembles Chromosomes Unwind Nucleus Chromosomes Unwind

ReCap! Mitosis – Makes 2 Identical Daughter Cells Other mnemonics: Prophase - Prepare Metaphase – Middle Anaphase – Away Telophase – The End Other mnemonics: PMAT Phil Makes Awesome Twinkies

What happens after mitosis is finished? 6. Answer: Cytokinesis! 7. What is cytokinesis? Cytokinesis is the splitting of the cytoplasm to make daughter cells.

How does cytokinesis work? Plants: Plant cells rebuild the cell wall. The partially finished cell wall is called a cell plate. Animals: Animal cells pinch in the cell membrane forming a cleavage furrow until both sides of the membrane meet, which separates the cells. Cell Plate Cleavage Furrow