Transcript Cell Cycle
Cell Cycle
Life of a Eukaryotic Cell
Cell Cycle
(Interphase in Red)
G1 – cell grows & carries out
major functions
S – DNA is copied
G2 – Prep for mitosis;
organelles reproduced
Mitosis – Nucleus divided into
two nuclei, each with same
number and kind of
chromosomes
Cytokinesis – cytoplasm
divides
Cell Cycle Control
How does cell “know” when to divide?
Cell cycle controlled by many proteins (enzymes) at
three main checkpoints:
G1 checkpoint – decision made whether cell will divide
(cell healthy and large enough). Some types of cell never
pass this point (nerve, muscle)
G2 checkpoint – Did DNA replication go OK? If so, go on
to mitosis
Mitosis checkpoint – Is mitosis over? If so, head to G1
phase
Cancer - What happens if
control is lost
Cancer = uncontrolled cell
Mutations:
growth
Disorder of cell division
Control mechanisms don’t
work (gene for proteins that
control cell cycle are
defective)
Overproduction of growthpromoting hormones –
speeds up cell cycle
Inactivation the control
proteins that act to slow or
stop cell cycle
Mitosis and Cytokinesis
Chromatids are physically
moved to opposite sides of
dividing cells with help of
spindle fibers
Centrosome (in animals) –
made up of two centrioles organizes assembly of
spindle fibers
Spindle fibers made from
microtubules
Mitosis and Cytokinesis
Chromatids separate by
attaching spindle fibers
Spindle fibers attach to
centromeres of
chromosomes
Paired chromatids separate.
One chromatid goes to one
pole of the cell, the other
chromatid goes to the other
as the spindle fibers shorten
Interphase (90% of cell’s time)
Mitosis (nuclear division)
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis (cytoplasmic division)
Watch video clip of mitosis
Another View of Mitosis
Mitosis Foldable
6 sheets of paper
Follow teacher’s instructions to construct booklet
You will make foldable based on pictures and
descriptions of interphase, cyokinesis, and mitosis in
your book (p. 125 and pp 130 – 132)
Include sketches and textual descriptions in foldable
You can also use www.cellsalive.com and
www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/m
ain.html
Headings for foldable
Cover = Phases of Somatic Cell Division
Following sheets –
Interphase
G1
S
G2
Mitosis
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Homework
Read Ch. 7 – “Meiosis and Sexual Reproduction”
Also read about plant reproduction pp. 534 – 535, and
pp. 538 – 539
Complete Guided Reading packet for Chapter 7
Complete Foldable