7. Each Chromosome (after the S phase) contains
two identical parts called “sister chromatids”
attached at a centromere (referred to as
“double stranded”)
8. • Interphase and Mitosis
• The cycle of growth and division in all cells
The Cell Cycle
12. • Either of two
submicroscopic
attachment points for
chromosomal
microtubules, present on
each centromere during
the process of cell
division
Kinetochore
15. • Several microtubules
joined together create
structures known as
spindle fibers which
guide chromosomes
during mitosis.
Spindle
Fibers
Spindle Fibers
Spindle Fibers
20. Cell Cycle
Regulation
Checkpoints during each
phase
Signals registered at the
checkpoints report the
status of various cellular
conditions (e.g., Is the
environment favorable? Is
the cell big enough? Is all
DNA replicated?
21. Molecular protein clocks that regulate the
activities of the cell cycle in a particular
order
Levels controlled by genes:
Proto-Onco Genes Stimulate
Tumor Supressor Genes Inhibit (p53 is a
common example)
p53 is a protein that functions to block the
cell cycle if the DNA is damaged. If the
damage is severe this protein can cause
apoptosis (cell death).
Cyclin Dependent Kinases
22. Cell Growth and Division
Also Regulated By
External Factors:
Density
Growth Factors
23. Cancer
Cancer cells do
not respond
normally to the
body's control
mechanisms.
They divide
excessively,
invade other
tissues and, if
unchecked, can
kill the whole
organism.
Abnormal cells
which have
escaped normal
cell-cycle
controls are the
products of
mutated or
transformed
normal cells.
A p53 mutation
is the most
frequent
mutation
leading to
cancer because
it prevents
apoptosis.
