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Cell Division. Mitosis vs. Meiosis ….the battle continues. Mitosis. Type = Asexual reproduction Growth, maintenance, and repair. Cell Cycle. Interphase Cells are in interphase 90% of the time. G1- growth S - chromosome replication G2- Prepare for mitosis - PowerPoint PPT Presentation
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Cell Cycle
• Interphase Cells are in interphase 90% of the time.
– G1- growth– S - chromosome
replication– G2- Prepare for mitosis
• Mitosis (nuclear division)
• Cytokinesis (cytoplasmic division)
Interphase (pre game show)
• Chromosomes are copied (# doubles)
• Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase
PROPHASECENTRIOLES APPEAR AND MOVE TO OPPOSITE ENDS OF THE CELL
Spindle fibers form between centrioles
METAPHASE
• Chromosomes “meet” in the middle. Spindle fibers attach to the centromere of each chromosome.
ANAPHASE
• Sister chromatids separate from each other and are “pulled” to opposite ends of the cell.
Telophase• Cell plate forms and cell membrane
begins pinching in= “cleavage.”• Chromosomes look like threads
(chromatin) again. Nuclear envelope forms again.
Meiosis: OverviewParent Cell: diploid= 2n
After Meiosis I
After Meiosis IIDaughter Cells:
Haploid= n ; and all genetically different from eachother and parent cell
???
Why would it be important for the gametes to contain half as many chromosomes
as a somatic cell?
Round of cell division
• Two
• Illustrate mother cell with four chromosomes (2n) and daughter cells with two chromosomes (n) in each. Make sure to include replication before meiosis I.
Let’s compare!
• http://www.teachersdomain.org/resources/tdc02/sci/life/gen/mitosis/index.html