cell cycle stages in growth & division g1 phase s phase g2 phase m phase cytokinesis...
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Cell CycleCell Cycle
Stages in growth & division
G1 Phase S Phase G2 Phase M Phase Cytokinesis
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G1 PhaseG1 Phase
First growth stageCell increases in sizeCell prepares to copy its DNA
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Synthesis PhaseSynthesis Phase
Copying of all of DNA’s instructions
Chromosomes duplicated
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G2 PhaseG2 Phase
Time between DNA synthesis & mitosis
Cell continues growingNeeded proteins produced
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M PhaseM Phase
Cell growth & protein production stop
Cell’s energy used to make 2 daughter cells
Called mitosis or karyokinesis (nuclear division)
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Life Cycle of a CellLife Cycle of a Cell
Mitosis is a cycle with no beginning or end.
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Interphase – Resting StageInterphase – Resting Stage
Cells carrying on normal activities
Chromosomes aren’t visibleCell metabolism is occurringOccurs before mitosis
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InterphaseInterphase
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Stages of MitosisStages of Mitosis
ProphaseMetaphaseAnaphaseTelophase
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Cells Undergoing MitosisCells Undergoing Mitosis
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Steps in ProphaseSteps in Prophase
DNA coils tightly & becomes visible as chromosomes
Nuclear membrane disappears Nuceolus disappears Centrioles migrate to poles Spindle begins to form
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ProphaseProphase
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Eukaryotic ChromosomeEukaryotic Chromosome
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Human ChromosomesHuman Chromosomes
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Steps in MetaphaseSteps in Metaphase
Spindle fibers from centrioles attach to each chromosome
Cell preparing to separate its chromosomes
Cell aligns its chromosomes in the middle of the cell
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MetaphaseMetaphase
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Steps in AnaphaseSteps in Anaphase
Cell chromosomes are separated
Spindle fibers shorten so chromosomes pulled to ends of cell
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Mitotic SpindleMitotic Spindle
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AnaphaseAnaphase
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Steps in TelophaseSteps in Telophase
Separation of chromosomes completed
Cell Plate forms (plants)Cleavage furrow
forms(animals)Nucleus & nucleolus reformChromosomes uncoil
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TelophaseTelophase
Plant Animalcopyright cmassengale
CytokinesisCytokinesis
Occurs after chromosomes separate
Forms two, identical daughter cells
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CytokinesisCytokinesis
Cell Plate Forming in Plant Cells copyright cmassengale
Chromosomes & Chromosomes & KaryotypesKaryotypes
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ChromosomesChromosomes
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Chromosome NumberChromosome NumberAll cells in the human body
(SOMATIC CELLS) have 46 or 23 pairs of chromosomes
Called the DIPLOID or 2n number
GAMETES (eggs & sperm) have only 23 chromosomes
Called the MONOPLOID or 1n number
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NondisjunctionNondisjunction
Chromosomes may fail to separate during meiosis
Resulting gametes may have too few or too many chromosomes
Disorders:– Down Syndrome – three 21st chromosomes– Turner Syndrome – single X chromosome– Klinefelter’s Syndrome – XXY chromosomes
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Normal MaleNormal Male
282n = 46
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Normal FemaleNormal Female
292n = 46
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Male, Trisomy 21 Male, Trisomy 21 (Down’s)(Down’s)
302n = 47
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Female Down’s Female Down’s SyndromeSyndrome
312n = 47
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Klinefelter’sKlinefelter’s Syndrome Syndrome
322n = 47
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Turner’s SyndromeTurner’s Syndrome
332n = 45
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