sc- b-2.6: summarize the characteristics of the cell cycle: interphase;the phases of mitosis, and...
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The Cell Cycle
SC- B-2.6: Summarize the characteristics of the cell cycle: interphase;the phases of mitosis, and plant & animal cytokinesis
Chromosomes
in nuclei of eukaryotic cellsmade up of:1. DNA2. Histones: proteins DNA wraps
around
The Cell Cycle
series of events that cells go through as they grow & divide
What a cell does in the cell cycle: grow prepares for division divides into 2 daughter cells
The Cell Cycle: Interphase time between cell divisions3 divisions:1. Gap 1 (G1)2. S Phase3. Gap 2 (G2)
Interphase:G1
cells do most of their growingmake proteins & organellescheckpoint cells destined never to divide
again leave cell cycle & enter G0
Interphase: S Phase
synthesis phasechromosomes duplicatedcells that enter S destined to go
thru mitosis
Interphase: G2
usually shortest part of interphase
material needed for cell division produced
checkpoint
Mitosis
4 phases:1. Prophase2. Metaphase3. Anaphase4. Telophase
each phase may last minutes to days depending on cell type
Mitosis: Prophase
longest phase of mitosischromosomes become visible
(chromatin condenses)centrioles separate & move to
opposite sides of nucleus
Mitosis: Prophase
centrioles start to organize mitotic spindle
nuclear envelope & nucleolus disappears
Cells in Prophase
Mitosis: Metaphase
chromosomes line up across center of cell = metaphase plate
centromere of each chromosome connected to spindle fiber
Cells in Metaphase
Mitosis: Anaphase
centromeres split pulling sister chromatids apart
as soon as split they are called chromosomes
as long as they are moving they are in anaphase
Cells in Anaphase
Mitosis: Telophase
chromosomes disperse & are no longer visible
2 nuclear envelopes reform & each nuclei starts to form a nucleolus
spindle breaks apartcleavage furrow becomes visible
Cells in Telophase
Cytokinesis
cytoplasm pinches in half each daughter cell has identical set of duplicate chromosomes
Cytokinesis in Plant Cellsrigid cell wall cannot “pinch” in
halfCell plate starts to form during
telophase cell wall between 2 daughter cells
Plant & Animal Cells Have Different Strategies for Cytokinesis