5.2 Mitosis and Cytokinesis
Chapter 5 Cell Growth and Division
Mr. Shilala
DAHS
KEY CONCEPT
Cells divide during mitosis and cytokinesis.
DNA and Chromosomes
• DNA is a double stranded molecule made of four
subunits called nucleotides
• A chromosome is one long continuous thread of
DNA
– Consists of numerous genes with regulatory information
– Your cells have 46 chromosomes
– If stretched out straight and laid end to end DNA in one cell would
be about 10 feet long
Chromosomes condense at the
start of mitosis.
• DNA is loosely organized during interpahse
– Looks like spaghetti
• DNA wraps around proteins (histones) that
condense (shrink) it.
• DNA plus proteins is called chromatin
DNA double
helix
DNA and
histones
Chromatin
Supercoiled
DNA
• Chromatid
•
One half of a duplicated
chromosome is a chromatid.
• Sister chromatids (identical
chromatids) are held together at the
centromere.
• Telomeres protect DNA and do not
include genes.
- Prevent chromosomes from
accidentally attaching to each
other
telomere
chromatid
centromere
telomere
Condensed, duplicated chromosome
Mitosis and cytokinesis produce two
genetically identical daughter cells.
Parent cell
• Interphase
prepares the
cell to divide.
• During
interphase, the
DNA, or
chromosomes,
are duplicated.
centrioles
spindle fibers
centrosome
nucleus with
DNA
Mitosis
• Mitosis divides the cell’s nucleus into 2
genetically identical nuclei in four stages
– Each has full set of DNA
• IPMAT
– Interphase
• Not part of mitosis
– Prophase
– Metaphase
– Anaphase
– Telophase
• Prophase
– DNA and Proteins condense into Chromosomes
– Nuclear membrane breaks down, centrioles
move to opposite poles and spindle fibers form
• Metaphase
– Chromosomes line up in the middle of the cell.
– Spindle fibers attach to each chromosome
• Anaphase
– Sister chromatids separate to opposite sides of
the cell.
• Telophase
– New nuclei form
– Chromosomes begin to uncoil
– Spindle fibers fall apart.
• Cytokinesis
– Cytokinesis is the division
of the cytoplasm into two
cells
– In animal cells, the
membrane pinches closed.
– In plant cells, a cell plate
forms
Youtube Mitosis Video