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Uploaded byLouie Jane Eleccion, LPT
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The Cell Cycle - Mitosis

The cell cycle consists of interphase and the M phase. Interphase includes G1, S, and G2 phases where the cell grows and duplicates its DNA. The M phase is when the cell divides through mitosis and cytokinesis. Mitosis consists of prophase, metaphase, anaphase, and telophase where the chromosomes align and separate. Cytokinesis then divides the cell cytoplasm. Uncontrolled cell division can lead to cancer.

Education◦
CELL CYCLE
• DNA synthesis - the process by which copies of nucleic acids are strung together to form a longer DNA sequence. • Restriction Point - one of several points in the eukaryotic cell cycle at which the progression of a cell to the next stage in the cycle can be halted until conditions are favorable (e.g. the DNA repaired). • Replication - The process of duplicating or producing an exact copy of a polynucleotide strand such as DNA. • Chromosomes - KEYWORDS
• In order for adult multicellular organisms to develop from a single fertilized egg, cell growth and division has to occur at the appropriate times and in the appropriate places. • When cell cycles proceed inappropriately (e.g., cells divide uncontrollably), pathological conditions like cancer can result. OVERVIEW
•Cells must accomplish two basic things during the cell cycle: • Copying cellular components • Dividing the cell so that components are distributed evenly to the daughter cells •The alternating “growth” and “division” activities of the cell is called the “cell cycle”.
M phase
INTERPHASE
INTERPHASE: G1 PHASE • Events during G1 oCell growth oPreparation of chromosomes for replication oDuplication of cellular components oG1 checkpoint (or restriction point); cell commits to division or exits from cell cycle
• DNA containing cell’s genetic code • Each chromosome has a matching pair -- Homologous Pair • During interphase, each chromosome copies itself
INTERPHASE: G0 PHASE • Also known as G1 checkpoint. • During the G0 phase, the cell cycle machinery is dismantled and cyclins and cyclin dependent kinases disappear. • Cell then remain in the G0 phase until there is a reason for them to divide. • Some cell types in mature organisms enter the G0 phase semi- permanently and can be induced to being dividing again only under very specific conditions. • Other types of cells, such as epithelial cells, continue to divide throughout an organism's life and rarely enter G0.
INTERPHASE: S PHASE • DNA replication • Duplication of the centrosome • The centrosome is located near the nucleus of the cell and contains the microtubule organizing center in animal cells. It contains two centrioles that migrate to the poles before cell division and serve to organize the spindle.
INTERPHASE: S PHASE
INTERPHASE: G2 PHASE • Cell growth • Checkpoint (restriction point) for entry into M phase.
MITOSIS Mitosis begins after G 2 and ends before G 1
CELL DIVISION: M PHASE • Process that divides cell nucleus to produce two new nuclei each with a complete set of chromosomes • Continuous process • Four phases (PMAT) • Prophase • Metaphase • Anaphase • Telophase
Cytokinesis
MITOSIS Mitosis is divided into 4 phases : 1. Prophase – 1st phase (longest) 2. Metaphase – 2nd phase 3. Anaphase – 3rd phase 4. Telophase – 4th (final) phase (think PMAT to recall order)
PROPHASE (FIRST) 1. Prophase – the 1st and longest phase of mitosis during which the : A. Chromosomes condense & become visible. B. Centrioles move to opposite sides of the nucleus. C. Nucleolus disappears. D. Nuclear membrane breaks down. E. Spindle (fanlike structure that helps separate chromosomes) forms. F. Spindle fibers attach to centromeres of chromosomes.
2. Metaphase – 2nd phase of mitosis during which the chromosomes line up across the center of the cell. (M&M : Meta = middle) METAPHASE
ANAPHAS E 3. Anaphase – 3rd phase of mitosis during which the centromeres split & individual chromatids move toward the poles. (AAA – in ANAPHASE chromosomes are pulled APART & move AWAY to opposite sides).
TELOPHA SE 4. Telophase – 4th & final phase of mitosis during which the : A. Chromosomes uncoil into a mass of material & can’t be seen. B. Nuclear membrane re-forms around each cluster of chromosomes. C. Spindles break apart. D. Nucleolus becomes visible in each daughter cell. *Cytokinesis usually occurs at the same time as Telophase.
CYTOKINESI S Cytokinesis – division of cytoplasm. -In animal cells cytokinesis occurs by drawing in the cytoplasm until it pinches into 2 parts (cleavage furrow). -In plant cells cytokinesis occurs when a structure known as the cell plate forms midway between the divided nuclei. The cell plate becomes a separating membrane & the cell wall forms in it.
PLANT CELL MITOSIS
2 TYPES OF CELL DIVISION
1.Name the phases starting at the top. Mitosis
2.Name the phase 3.Identify X 4.Identify Y
5. Name the phase
6. Name the phase
CANCER CELLS • Result of uncontrolled cell division of cells that have lost ability to regulate cell cycle • Reproduce more rapidly than normal cells • Masses formed called ‘tumors’