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ch.12
cell cycle
Question | Answer |
---|---|
How many number of chromosomes do somatic cells have? | two sets |
How many number of chromosomes do gametes cells have? | half as many chromosomes as somatic cells |
what is the centromere? | the narrow "waist" of the duplicated chromosome, where the two chromatids are most closely attached |
What is mitosis? | the division of the nucleus |
what is cytokinesis? | the divison of the cytoplasm |
What are gametes produced by? | meiosis |
what are meiosis? | yields nonidentical daughter cells that have only one set of chromosomes, half as many as the parent cell |
what are the phases of the cell cycle? | - Mitotic phase - Interphase |
what is interphase? | cell growth and copying of chromosomes in preparation for cell divison |
what are the 3 subphases of interphase? | - G1 phase - S phase - G2 phase |
what are the 5 phases of mitosis? | - prophase - prometaphase - metaphase - anaphase - telophase |
what is the mitotic spindle? | an apparatus of microtubules that controls chromosome movement during mitosis |
how are spindle microtubules assembled? | - they begin in the centrosome, the microtubule organizing center - the centrosomes replicates, forming two centrosomes that migrate to opposite ends of the cell - an aster extends from each centrosome |
what happens in anaphase? | - sister chromatids separate and move along the kinetohore microtubules toward opposite ends of the cell - the microtubules shorten by depolymerizing at their kinetochore ends |
what happens in binary fission? | the chromosome replicates and the two daughter chromosomes actively move apart |
What is so important about the G1 checkpoint? | this is where a cell receive a go-ahead signal and go into the S,G2,and M phase and divide |
what happens if the cell does not receive the go ahead signal? | it will exit the cycle, switching into a non dividing state called the G0 phase |
what are two types of regulatory proteins involved in cell cycle control? | cyclins and cyclin-dependent kinases |
what is an example of an internal signal? | when kinetochores not attached to spindle microtubules send a molecular signal that delays anaphase |
What are some external signals? | growth factors, proteins released by certain cells that stimulate other cells to divide |