Download 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- Is a double helix molecule made
of 4 subunits called nucleotides.
• Genes- region of DNA that codes for,
or makes, a specific protein.
• Chromosomes- Long strands of DNA
that consists of numerous genes.
5.2 Mitosis and Cytokinesis
Chromosomes condense at the start of mitosis.
• DNA wraps around proteins that organize and condense it.
- Histones- are proteins that DNA wraps itself around
at regular intervals to keep the DNA from getting
tangled up.
– During Interphase, DNA is loosely organized, like a plate
of spaghetti, but during Mitosis DNA is tightly packed
together.
- Because during Interphase proteins must have
access to the DNA, and during Mitosis DNA will get
tangled up if is loosely packed
5.2 Mitosis and Cytokinesis
Chromosomes condense at the start of mitosis.
DNA double
helix
DNA and
histones
Chromatin
Supercoiled
DNA
5.2 Mitosis and Cytokinesis
• Chromatin- is the loose combination of DNA and Proteins
telomere
• As the cell progresses through chromatid
mitosis, chromatin condense
further, and for thick rods.
• Chromosomes have already been
centromere
copied during the S phase.
• Eventually they form an “X” in
which the left and right halves are
2 identical DNA
• Chromatid- is one half of the “X”
• Sister Chromatids- both halves
• Centromeres- region of pinched
telomere
chromsomes. (middle of the “X”)
Condensed, duplicated chromosome
• Telomeres- regions at end of “X”
5.2 Mitosis and Cytokinesis
Mitosis and cytokinesis
Parent cell
• The process of
Mitosis and
Cytokinesis produce
two identical
daughter cells from
parent cell.
• Before the Mitosis
phase starts the cell
is in Interphase (G1,
S, M phases)
centrioles
spindle fibers
centrosome
nucleus with
DNA
5.2 Mitosis and Cytokinesis
• Mitosis divides the cell’s nucleus in four phases.
– 1) Prophase- Chromatin condese into the “X” and
from sister chromatid. The nuclear envelope
breaks down. Centrosomes and Centriols start to
migrate to opposite ends of the cell, and spindle
fibers start to grow.
5.2 Mitosis and Cytokinesis
• Mitosis divides the cell’s nucleus in four phases.
– Metaphase- chromosomes line up in the middle of the
cell and the spindle fibers attach to a chromotid pair.
5.2 Mitosis and Cytokinesis
• Mitosis divides the cell’s nucleus in four phases.
– Anaphase- spindle fibers begin to shorten and
pull sister chromatids appart to opposite sides of
the cell.
5.2 Mitosis and Cytokinesis
• Mitosis divides the cell’s nucleus in four phases.
– Telophase- a set of identical chromatides are positioned
at the opposite side of the cell, nuclear membranes start
to form, chromsomes begin to uncoil, and spindle fibers
begin to fall apart.
5.2 Mitosis and Cytokinesis
• The last stage of Cell Cycle.
– Cytokinesiscytoplasm and
organelles are
divided into two cells
that are identical.
– Animal cellsmembrane “pinches”
in on itself.
– Plant cells- a “cell
plate” forms b/w the
2 nuclei, allowing
cellulose to be laid
down on the plate to
form a cell wall.
5.2 Mitosis and Cytokinesis
REMEMBER!
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
IPMATC
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