• __________ (example: baby  adult)
• ___________________ (asexual reproduction
in single celled organisms)
• ____________________________
of dead/damaged/infected (example: skin/red
blood cells/bone cells)
• ______________________ formation in multicellular organisms (meiosis)
• In eukaryotes: made up of ____________and
_____________
• At different times, proteins cause the DNA to:
– be ________________________like spaghetti in
a bowl
– be tightly _______________into the X-shaped
(these we can see in the microscope)
• Central constricted region called
_________________ that serves as an
attachment point for the spindle fibers during
mitosis.
• Chromosomes exist in 2 different states:
- before DNA replication, chromosomes
have one _____________________.
- after DNA replication, chromosomes have
2 sister _________________, held together
at the ___________________. Each
chromatid is one piece of DNA with its
supporting ____________________.
• Why is DNA replication necessary?
Cell Cycle
__________________________:
Longest part of the cell cycle
Includes G1, S and G2
G1: cell ________________
S: cell growth; _________________________
G2: cell growth; organelles _________________
DNA begins to ___________________ into
chromosomes
• _________is the division of the eukaryote nucleus, which
goes on throughout life in all parts of the body.
• Organelles can be randomly separated into the daughter
cells but chromosomes must be precisely divided so that
each daughter cell gets exactly the _______________DNA.
• Every human cell has the same __________
chromosomes
• Mitosis is usually divided into 4 phases:
• Prophase (P)
• ___________________(M)
• Anaphase (A)
• ___________________(T)
Phases of Mitosis:
1. __________________________
Chromatin finishes ___________________ into
chromosomes (visible under light microscope)
Nucleolus/nuclear envelope
___________________ down
Spindle fibers form from
centrosomes/_________________ with
microtubules extending out
Chromosomes appear as 2 identical sister
chromatids joined together at centromeres
2. Metaphase
_________________ stage of mitosis
Chromosomes move to ______________of cell
(metaphase plate)
Chromosome’s centromeres are on metaphase
plate with sister chromatids each facing
opposite sides of cell
______________________ at opposite sides of
cell
3. Anaphase:
_______________ stage of mitosis
Sister chromatids ________________ and begin
moving towards __________________ends of
cell (spindle fibers pull sister chromatids in via
the centromere) and each one is now a
“___________________”
Cell elongates
At end of phase, each end of the cell contains
complete and _____________________
chromosomes
4. _________________________:
-Chromosomes are at each side of cell and
__________________ begins to re-form
around
-Chromosomes _________________to form
_____________________
-Spindle fibers disintegrate
-Cell is elongated and ready for
______________________
Animal Cell
Cytokinesis
inward ______________
of plasma membrane to
form
__________________
_________________
Plant Cell
Cytokinesis
cell __________
forms and moves
outward towards the
sides of the cell from
central region
• _________________= result of uncontrolled cell division
• The genetic checks that stop cells from reproducing fail to work
and they grow out of control
• _______________ = gene that turns a normal cell into a cancer
cell
• Tumors can occur in any organ or tissue, though are most
common after exposure to carcinogens (e.g. tobacco smoke) or in
particularly active tissues (e.g. breast, skin)
• Angiogenesis: tumor recruits blood vessels and grows larger
• Metastasis: part of the tumor invades the blood vessel, travels
through the blood and starts to forma a tumor in another part of
the body
Normal cells are controlled by several factors:
Normal cells stay in the G1 stage of the cell cycle until they
are given a specific signal. Cancer cells enter the S phase
without waiting for a signal.
Normal cells are mortal. This means that they can divide
about 50 times and then they lose the ability to die. This
“clock” gets re-set during the formation of the gametes.
Cancer cells escape this process of mortality: they are
immortal and can divide endlessly.
Normal cells that suffer significant chromosome damage
destroy themselves due to the action of a gene called “p53”.
Cancer cells either lose the p53 gene or ignore its message
and fail to kill themselves (process known as apoptosis)