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Cell Division: Mitosis & Cytokinesis

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Presentation on theme: "Cell Division: Mitosis & Cytokinesis"— Presentation transcript:

1 Cell Division: Mitosis & Cytokinesis
Define mitosis and cytokinesis Describe the cell cycle and the changes that take place during interphase Discuss the events and significance of mitosis

2 Chromosomes Chromosomes: “colored body”
seen only when the cell divides contain genetic info in the form of DNA are coiled chromatin Composition of Chromatin Make up chromosomes Composed of DNA and protein called histones (helps to condense the DNA) DNA in a chromosome is 10,000x longer than the chromosome itself Must condense in order to separate correctly during mitosis

3 Chromosome Structure Can only see chromosomes during division
Each chromosome replicates and is paired as sister chromatids joined at a centromere Human cell has 46 chromosomes (2n) “n” number = 23 = “haploid” 2n = 46 = “diploid” 4n = 92 (during interphase) Body cells (aka somatic cells) = 2n = 46 Sex cells (aka eggs & sperm) = n = 23

4 The Cell Cycle ______________
Growth, prepares for division, divides (anywhere from 6 hours to 100 days) 3 Parts: ______________ ______________ (PMAT) - few minutes to several days

5 Interphase – 3 stages More than _____% of the life of a cell is spent in this phase G1: cell growth, development, and __________ production (longest) S: “Synthesis”, ___ replication G2: __________ replicated (shortest) Note: DNA exists as _________ (no chromosomes yet)

6 Mitosis - Prophase __________ phase of mitosis (50-60 % of total time required for mitosis) Nuclear __________ starts to disintegrate Chromosomes condense (become visible) – seen as 2 identical __________ lying side by side held together by __________ __________ move to opposite poles Spindle __________ grow from centrioles, attach at centromeres

7 Mitosis – Metaphase (hint “m”=middle)
Chromosomes attach to the _____________ Chromosomes line up in the middle (aka equator) Spindle fibers run from __________ to __________ of the chromosomes

8 Mitosis - Anaphase (hint “a” = away)
__________ split Spindles retract and pull sister __________ apart Chromosomes move to __________ poles (toward centrioles)

9 Mitosis - Telophase Chromosomes cluster at __________
Chromosomes uncoil back into __________ Nuclear envelope reforms around each new _____ Mitosis is done Cell __________ begins to pinch in the middle

10 Cytokinesis Cell membrane moves __________ and pinches in the middle forming two __________ cells In plant cells – a cell __________ (eventually becomes the cell wall) and cell membrane appear separating the 2 new cells There are now 2 identical cells – same DNA, etc.

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