Transcript 5.2 Mitosis and Cytokinesis

5.2 Mitosis and Cytokinesis
KEY CONCEPT
Cells divide during mitosis and cytokinesis.
5.2 Mitosis and Cytokinesis
Chromosomes condense at the start of mitosis.
• DNA wraps around proteins (histones) that condense it.
DNA double
helix
DNA and
histones
Chromatin
Supercoiled
DNA
5.2 Mitosis and Cytokinesis
• DNA plus proteins is called chromatin.
chromatid
• One half of a duplicated
chromosome is a chromatid.
• Sister chromatids are held
together at the centromere.
• Telomeres protect DNA and do
not include genes.
telomere
centromere
telomere
Condensed, duplicated chromosome
5.2 Mitosis and Cytokinesis
Mitosis
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase
5.2 Mitosis and Cytokinesis
Mitosis and cytokinesis produce two genetically identical
daughter cells.
Parent cell
• Interphase prepares
the cell to divide.
• During interphase,
the DNA is
duplicated.
Interesting things happen!
centrioles
spindle fibers
centrosome
nucleus with
DNA
5.2 Mitosis and Cytokinesis
Prophase
•
1.
Chromosome pair up!
Chromosomes thicken and shorten
-become visible
-2 chromatids joined by a centromere
2. Centrioles move to the opposite sides of the
nucleus
3. Nucleolus disappears
4. Nuclear membrane disintegrate
5.2 Mitosis and Cytokinesis
• Mitosis divides the cell’s nucleus in four phases.
– During prophase, chromosomes condense and
spindle fibers form.
5.2 Mitosis and Cytokinesis
Metaphase
•
1.
2.
3.
Chromosomes meet in the middle!
Chromosomes arrange at equator of cell
Become attached to spindle fibres by centromeres
Homologous chromosomes do not associate
5.2 Mitosis and Cytokinesis
• Mitosis divides the cell’s nucleus in four phases.
– During metaphase, chromosomes line up in the
middle of the cell.
5.2 Mitosis and Cytokinesis
Anaphase
•
1.
Chromosomes get pulled apart
Spindle fibres contract pulling chromatids to the
opposite poles of the cell
5.2 Mitosis and Cytokinesis
• Mitosis divides the cell’s nucleus in four phases.
– During anaphase, sister chromatids separate to
opposite sides of the cell.
5.2 Mitosis and Cytokinesis
Telophase
•
1.
2.
3.
4.
Now there are two!
Chromosomes uncoil
Spindle fibres disintegrate
Centrioles replicate
Nucleur membrane forms
5.2 Mitosis and Cytokinesis
• Mitosis divides the cell’s nucleus in four phases.
– During telophase, the new nuclei form and
chromosomes begin to uncoil.
5.2 Mitosis and Cytokinesis
• Cytokinesis differs in animal and plant cells.
– In animal cells, the
membrane pinches
closed.
– In plant cells, a cell
plate forms.
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
• https://www.youtube.com/watch?v=ofjyw7ARP1c