Chapter 4: Cell Growth and the Division of the Cell
Growth Phase of the Cell Cycle
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Less Common Types of Cell Division
S Phase
G2 Phase
G1 Phase
First phase after division
Cell recovers from division and conducts most of its normal metabolism
Generally the longest part of the cell cycle
Entire complex of genes for an organism is called a genome
Involves formation of chromosomes, endoreduplication, gene amplification, and the use of the centromere and telemere
Called the Synthesis Phase - genes in the nucleus are duplicated
DNA winds around each histone cylinder and then forms into a compact arrangement
Chromatin and centrioles are used
Lasts only 3-5 hours
Alpha and beta tubulins are synthesized
Occurs after S Phase - Cells prepare for division
Cell produces factors necessary to start nuclear division
G1, S, and G2 Phase makes up the interphase portion of the cell cycle
Division Phase of the Cell Cycle
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Mitosis
Meiosis 1 and 2
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Duplication Division
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Prophase
Nucleolus become less distinct and completely disappears by the end of prophase
Nuclear envelop breaks into numerous vesicles
Chromosomes condense and begin to coil repeatedly - continues till the chromosomes are only 2-5 um long
Daughter cells migrate to opposite poles
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Telophase
Chromosomes become less instinc
Most phases of telophase are reversals of prophase
Fragments of the nuclear envelope appear near chromosomes, connect with each other, and form complete nuclear envelopes at each end of the cell
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Metaphase
At the end of this phase - separase is activated and it digests cohesin
Number of chromosomes are doubled but the size of the chromosomes are halved
Chromosomes gradually become invisible and gradually move to the metaphase plate
After spindle microtubules attach to centromeres, they push and pull on the chromosomes and gradually move them to the cell center - metaphase plate
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Anaphase
As chromosomes on each side get closer to the end, they are pulled together into a compact space
Long chromosomes may tangle somewhat
Spindle microtubules that run to the kinetochores shorten
Begins just after cohesin releases the centromeres
Daughter chromosomes are pulled away from its twin
Cytokinesis
Karyokinesis
2 sex cells fuse together
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Metaphase 1and 2
Anaphase 1 and 2
Prophase 1 and 2
Telophase 1 and 2
division of a cell nucleus during mitosis.
The cytoplasmic division of a cell at the end of mitosis or meiosis this eventually brings about the separation into two daughter cells.