Transcript Mitosis Notes

Cell Division: Mitosis
• Cell theory
– All cells come from pre-existing cells
– Cells are the basic unit of organization of
organisms.
– All living things are made of cells.
Cell Division
•The process when 2 cells are produced from
one cell
•Begins with one parent cell
•Results in 2 daughter cells identical to the
parent cell
• Chromosomes--carriers of the genetic material
that is copied and passed from generation to
generation of cells.
The structure of eukaryotic chromosomes
Centromere
Sister
chromatids
Supercoil within
chromosome
Chromosome
Continued coiling
within supercoil
Histone H1
Nucleosome
DNA
• Cell cycle—sequence of growth and division
of a cell, divided into 3 main periods
– Interphase
– Mitosis
– Cytokinesis
Mitosis
Interphase
Cytokinesis
• Interphase—Cell grows in size, carries on
metabolism, makes DNA, and prepares for
division
Interphase
DNA synthesis
and replication
Rapid
growth
and
metabolic
activity
Centrioles replicate;
cell prepares for
division
• Mitosis—Process of cell division where 2
identical daughter cells are formed
Mitosis is divided into 4
phases—prophase,
metaphase, anaphase,
telophase
Mitosis
Prophase: longest phase of mitosis
• Chromatin--coils into visible chromosomes
• Sister chromatids— doubled strands of
DNA held together by a centromere
Spindle fibers
Disappearing
nuclear
envelope
Doubled
chromosome
Prophase
• Nuclear envelope— begins to disappear and
nucleolus disintegrates
• Centrioles—are in opposite ends of the cell
• Spindle Fibers are formed
Spindle fibers
Disappearing
nuclear
envelope
Doubled
chromosome
Sister Chromatids
Centromere
Sister chromatids
Metaphase: shortest phase
• Doubled chromosomes are lined up along the
equator (middle) of the cell
Centromere
Sister
chromatids
Anaphase
• Chromosomes are pulled apart at the
centromere and separated
Telophase
• Chromatids are in different sides of the cell
• Chromatids unwind
• Nuclear envelope and nucleolus reappear
• Cell membrane begins to split cell in 2
Nuclear
envelope
reappears
Two daughter cells are formed
• Cytokinesis— process where the cell’s
cytoplasm divides between 2 new cells
– In animal cells—2 cells are separated by
membrane “pinching in” between them
– In plant cells—2 cells are separated by a
cell plate that forms in between them
Mitosis
Prophase
Metaphase Anaphase
Telophase
Mitosis
Prophase Metaphase Anaphase Telophase
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