Mitosis 1 Division Mitosis of the nucleus Also

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Mitosis 1

Mitosis 1

ü Division Mitosis of the nucleus ü Also called karyokinesis ü Only occurs in

ü Division Mitosis of the nucleus ü Also called karyokinesis ü Only occurs in eukaryotes ü Has four stages ü Doesn’t occur in some cells such as brain cells 2

Four Mitotic Stages ü Prophase ü Metaphase ü Anaphase ü Telophase 3

Four Mitotic Stages ü Prophase ü Metaphase ü Anaphase ü Telophase 3

Early Prophase ü Chromatin in nucleus condenses to form visible chromosomes ü Mitotic spindle

Early Prophase ü Chromatin in nucleus condenses to form visible chromosomes ü Mitotic spindle forms from fibers in cytoskeleton or centrioles (animal) Nucleolus Cytoplasm Nuclear Membrane Chromosomes 4

Late Prophase ü Nuclear membrane & nucleolus are broken down ü Chromosomes continue condensing

Late Prophase ü Nuclear membrane & nucleolus are broken down ü Chromosomes continue condensing & are clearly visible ü Spindle fibers called kinetochores attach to the centromere of each chromosome ü Spindle finishes forming between the poles of the cell 5

Late Prophase Chromosomes Nucleus & Nucleolus have disintegrated 6

Late Prophase Chromosomes Nucleus & Nucleolus have disintegrated 6

Spindle Fiber attached to Chromosome Kinetochore Fiber Chromosome 7

Spindle Fiber attached to Chromosome Kinetochore Fiber Chromosome 7

Review of Prophase What the cell looks like What’s happening 8

Review of Prophase What the cell looks like What’s happening 8

Spindle Fibers The mitotic spindle form from the microtubules in plants and centrioles in

Spindle Fibers The mitotic spindle form from the microtubules in plants and centrioles in animal cells ü Polar fibers extend from one pole of the cell to the opposite pole ü Kinetochore fibers extend from the pole to the centromere of the chromosome to which they attach ü Asters are short fibers radiating from centrioles ü 9

Sketch The Spindle 10

Sketch The Spindle 10

Metaphase üChromosomes, attached to the kinetochore fibers, move to the center of the cell

Metaphase üChromosomes, attached to the kinetochore fibers, move to the center of the cell üChromosomes are now lined up at the equator Equator of Cell Pole of the Cell 11

Metaphase Aster Chromosomes at Equator 12

Metaphase Aster Chromosomes at Equator 12

Review of Metaphase What the cell looks like What’s occurring 13

Review of Metaphase What the cell looks like What’s occurring 13

Anaphase ü Occurs ü Sister rapidly chromatids are pulled apart to opposite poles of

Anaphase ü Occurs ü Sister rapidly chromatids are pulled apart to opposite poles of the cell by kinetochore fibers 14

Anaphase Review What the cell looks like What’s occurring 15

Anaphase Review What the cell looks like What’s occurring 15

Telophase üSister chromatids at opposite poles üSpindle disassembles üNuclear envelope forms around each set

Telophase üSister chromatids at opposite poles üSpindle disassembles üNuclear envelope forms around each set of sister chromatids üNucleolus reappears üCYTOKINESIS occurs üChromosomes reappear as 16

Comparison of Anaphase & Telophase 17

Comparison of Anaphase & Telophase 17

Cytokinesis ü Means division of the cytoplasm ü Division of cell into two, identical

Cytokinesis ü Means division of the cytoplasm ü Division of cell into two, identical halves called daughter cells ü In plant cells, cell plate forms at the equator to divide cell ü In animal cells, cleavage furrow forms to split cell 18

Cytokinesis Cleavage furrow in animal cell Cell plate in plant cell 19

Cytokinesis Cleavage furrow in animal cell Cell plate in plant cell 19

Mitotic Stages 20

Mitotic Stages 20

Daughter Cells of Mitosis ü Have the same number of chromosomes as each other

Daughter Cells of Mitosis ü Have the same number of chromosomes as each other and as the parent cell from which they were formed ü Identical to each other, but smaller than parent cell ü Must grow in size to become mature cells (G 1 of Interphase) 21

Identical Daughter Cells What is the 2 n or diploid number? 2 Chromosome number

Identical Daughter Cells What is the 2 n or diploid number? 2 Chromosome number the same, but cells smaller than parent cell 22

Review of Mitosis 23

Review of Mitosis 23

Eukaryotic Cell Division Used for growth and repair ü Produce two new cells identical

Eukaryotic Cell Division Used for growth and repair ü Produce two new cells identical to the original cell ü Cells are diploid (2 n) ü Prophase Metaphase Anaphase Chromosomes during Metaphase of mitosis Telophase Cytokinesis 24

Mitosis Animation Name each stage as you see it occur? 25

Mitosis Animation Name each stage as you see it occur? 25

Mitosis in Onion Root Tipsof mitosis? Do you see any stages 26

Mitosis in Onion Root Tipsof mitosis? Do you see any stages 26

Name the Stages of Mitosis: Early prophase Early Anaphase Metaphase Interphase Late Prophase Late

Name the Stages of Mitosis: Early prophase Early Anaphase Metaphase Interphase Late Prophase Late telophase, Advanced cytokinesis Early Telophase, Begin cytokinesis Mid-Prophase Late Anaphase 27

Identify the Stages ? Early, Middle, & Late Prophase ? ? Metaphase Late Prophase

Identify the Stages ? Early, Middle, & Late Prophase ? ? Metaphase Late Prophase Anaphase ? ? Late Anaphase ? Telophase ? Telophase & Cytokinesis 28

Locate the Four Mitotic Stages in Plants Anaphase Telophase Metaphase Prophase 29

Locate the Four Mitotic Stages in Plants Anaphase Telophase Metaphase Prophase 29

Uncontrolled Mitosis If mitosis is not controlled, unlimited cell division occurs causing cancerous tumors

Uncontrolled Mitosis If mitosis is not controlled, unlimited cell division occurs causing cancerous tumors ü Oncogenes are special proteins that increase the chance that a normal cell develops into a tumor cell ü Cancer cells 30