Transcript The Cell Cycle

The Cell Cycle
What is the life cycle of a cell?
• Is it like this?
– Birth
– Growth &
development
– Reproduction
– Deterioration & Death
• Or is it like this?
– Birth
– Growth &
development
– Deterioration & Death
Cell Reproduction
• Organisms are not born
with all the cells they will
ever have.
• Organisms grow, and as
they grow, their cells
reproduce to make more
cells.
• Prokaryotes & eukaryotes
do this differently.
Prokaryotes: Cell Reproduction
• Prokaryotes (like
bacteria) reproduce
asexually.
• They split in two.
This process is called
binary fission.
Eukaryotes: Cell Reproduction
• Eukaryotes reproduce
sexually and asexually.
• Reproductive cells
undergo sexual
reproduction.
• All other cells in the body,
called somatic cells,
undergo asexual
reproduction to replace
damaged cells and allow
you to grow.
• This asexual reproduction
is also called mitosis.
The Cell Cycle
• Mitosis is a small part
of the cell cycle.
• Most of its life, the
cell is not in mitosis,
but in interphase.
• Both mitosis and
interphase consist of
several stages.
The Cell Cycle: Overview
•What is cancer?
Cancer is caused by
mutations (change or
damage) in the genes that
regulate the cell cycle at its
checkpoints. When these
checkpoints fail, the result
is uncontrolled cell
division- also known as
cancer.
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.html
Interphase
• Interphase has 3
stages- G1, S, & G2
• During interphase,
cells grow by making
proteins, copies of
their DNA, and extra
organelles.
• (The S phase is when
DNA replication
occurs.)
Interphase: continued
• At the end of
interphase, all of the
DNA condenses into
fibers in the nucleus
called chromatin.
• The chromatin, in
turn, will condense
into thick segments
called chromosomes
in Prophase.
Chromosomes
• Each chromosome
consists of 2 identical
chromatids.
• These chromatids are held
together by a centromere.
• The centromere will attach
the chromatids to the
spindle in mitosis. Later
on, these chromatids will
be separated.
Prophase
• In prophase, the
chromosomes become
clearly visible.
• The nuclear membrane
disappears.
• Structures called
centrioles move to
opposite ends of the
cell, and spindle fibers
form between them.
Metaphase
• During metaphase, the
chromosomes line up
in the middle of the
cell.
• Each chromosome is
attached to a spindle
fiber that ends at one
of the centrioles.
Anaphase
• Anaphase is
characterized by the
chromosomes being
pulled apart to
opposite sides of the
cell.
Telophase
• The last stage of
mitosis is telophase.
• During telophase,
nuclear membranes
reform around the
chromosomes at each
end of the cell.
• Chromosomes unwind
to chromatin and
DNA.
Cytokinesis
• The very last part of cell
reproduction is the
division of cytoplasm.
This is called cytokinesis.
• In plant cells, cytokinesis
is complete when the cell
plate has completely
formed between both new
nuclei, and two new
daughter cells are made.
• In animal cells, a cleavage
furrow is seen when the
cell cytoplasm pinches
inward to form the two
new daughter cells.
Mitosis Animations
Mitosis Animations
http://bcs.whfreeman.com/thelifewire/content/chp09/0902001.html
http://www.hybridmedicalanimation.com/anim_mitosis.html
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation_
_mitosis_and_cytokinesis.html
Game:
http://nobelprize.org/educational_games/medicine/2001/cellcycle.html