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Cell Cycle PowerPoint Presentation

Cell Cycle

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Cell Cycle

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  1. Cell Cycle

  2. Objective • Describe the stages of mitosis. • List types of asexual reproduction

  3. The cell cycle- series of events that takes place from one cycle to the next. • During Interphase-hereditary material (DNA) is copied and the cell grows and prepares for cell division.

  4. Mitosis • Prophase- nucleolus and nuclear membrane disintegrate. • Centrioles move to opposite ends of the cell. • Thread like spindle fibers begin to stretch across the cell. • Metaphase- the pairs of chromatids line up across the center (middle of the cell).

  5. Anaphase- each centromere divides. Each pair of chromatids separates and moves to the opposite ends of the cell. • Telophase- spindle fibers disapper and a new nucleus forms. • Division of the cyotplasm- animal cells- the membrane pinches in the middle and the cytoplasm divides. Plant cells- cell plate forms

  6. Results of Mitosis- It produces two nuclei that are IDENTICAL.

  7. Asexual Reproduction • Asexual reproduction is when a neworganism is produced from one organism. Organisms make other organisms’ like themselves. In asexual reproduction a single parent produces offspring that is identical to the parent. Most single cell organisms reproduce this way. Examples are budding, regeneration. (fission)

  8. Prophase • Chromatin in the nucleus begins to condense and becomes visible in the light microscope as chromosomes. The nucleolus disappears. Centrioles begin moving to opposite ends of the cell and fibers extend from the centromeres. Some fibers cross the cell to form the mitotic spindle.

  9. Metaphase • Spindle fibers align the chromosomes along the middle of the cell nucleus. This line is referred to as the metaphase plate. This organization helps to ensure that in the next phase, when the chromosomes are separated, each new nucleus will receive one copy of each chromosome.

  10. The paired chromosomes separate at the kinetochores and move to opposite sides of the cell. Motion results from a combination of kinetochore movement along the spindle microtubules and through the physical interaction of polar microtubules. Anaphase Anaphase

  11. Telophase • Chromatids arrive at opposite poles of cell, and new membranes form around the daughter nuclei. The chromosomes disperse and are no longer visible under the light microscope. The spindle fibers disperse, and cytokinesis or the partitioning of the cell may also begin during this stage.

  12. Cytokinesis • In animal cells, cytokinesis results when a fiber ring composed of a protein called actin around the center of the cell contracts pinching the cell into two daughter cells, each with one nucleus. In plant cells, the rigid wall requires that a cell plate be synthesized between the two daughter cells.

  13. Objective • Explain why meiosis is needed for sexual reproduction • Name the cells needed for sexual reproduction

  14. During sexual reproduction, two sex cells eggs (female) and sperm (male), called a sperm and an egg come together. • The joining of an egg and a sperm is called fertilization, and that cell is called a zygote.

  15. A typical cell in the human body has 46 chromosomes. • Human body cells have 23 pairs of chromosomes, when cells have similar pairs of chromosomes they are said to be diploid. • Because sex cells do not have pairs of chromosomes, they are said to be haploid.

  16. Meiosis and Sex Cells • A process called meiosis produces haploid sex cells, which only have 23 chromosomes.

  17. Objectives

  18. DNA stands for deoxyribonucleic acid. • It contains the information for an organism’s growth and function.

  19. Most of your characteristics depend on the kinds of proteins your cells make. • Your DNA stores the instructions for making these proteins. • The instructions for making a specific protein are found in a gene, which is a section of DNA found on a chromosome.

  20. Mutations • If DNA is not copied exactly, the proteins made from the instructions might not be made correctly. • These mistakes are called mutations, which are a permanent change in the DNA sequence. • Mutations can be beneficial or harmful.