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14 Cards in this Set
- Front
- Back
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define mitosis: |
process of nuclear division 2 genetically identical nuclei containing same number of chromosomes are formed from 1 parent cell nucleus. |
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4 reasons for making new cells through mitosis: |
-growth. -repair. -asexual production. -replacement of old cells. |
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what are the main stages of mitosis? |
prophase metaphase anaphase telophase. |
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What happens during Interphase? |
-DNA is replicated to form an extra copy of each chromosome (still part of the same chromosome as a chromatid). -Centrosome which later forms the spindle is also replicated. |
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What Happens during early prophase? |
-The DNA continues condensing (super coil) into chromosomes. -Nuclear membrane begins to erode -nucleolus disappears. -each duplicate chromosome is seen as a pair of sister chromatids joined by the duplicate but unseated centromere. |
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What happens during the late prophase? |
-Chromosomes continue to condense. into visible form -The nuclear envelope disappears at the end of prophase. -mitotic spindle forms consisting of microtubules forming between the two pairs of centrioles as. -centrioles move to opposite ends of the cell.
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What is the role of the Mitotic spindle? |
organises the chromosomes on the equator of the cell. |
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What happens during metaphase? |
-From chromosomes now at their most highly coiled become arranged in the middle. -each chromosome becomes attached to the spindle thread because the spindle locks on to the centromere of each of the 4 chromosomes. |
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what happens during anaphase? |
-centromeres split chromatids pulled apart -now each chromatid is now effectively its own chromosome -spindle fibres shorten pulling the chromatids further apart to opposite poles of the cell towards the centrioles
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what happens during telophase? |
-new nuclear envelope forms around each individual set of chromatids to create 2 new nuclei -spindle breaks down and disappears -chromosomes begin to unwind again -cell splits in two.
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what is cytokinesis? |
cell cytoplasm divides to create two distinct daughter cells. |
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What is the purpose of mitosis? |
- growth -repair -produces cells with 2n chromosome number -allows some animals re-produce asexually |
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What is the purpose of meiosis? |
Cell division for producing gametes with 1n chromosome number. |
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State two important changes that chromosomes must undergo before cell division can take place? |
Replicated DNA to form a second chromatid Coil into visible chromosomes to avoid tangling |
