Cell cycle
 Interphase
 Mitosis
 Cytokinesis
 Spindle
 Centrosome

Eukaryotic Cell Cycle: Discovery Reading Questions
1. The first three phases together are known as ______.
Name & describe the phases.
a.
b.
c.
The remaining two phases make up _______.
Name & describe the phases.
d.
e.
2. Which stage do most cells (except skin cells) spend most of
its time in?
3. Which stage is DNA copied in?
4. What is mitosis?
5. What’s the significant difference between mitosis &
cytokinesis?
2 books per group.
 Work with books in partners.

 Identify
and restate what the
phases of the eukaryotic cell
cycle are.
 Restate what happens in each
stage of the cycle.

You know that a cell goes through division
for three main reasons:
› To replace old or…
› To repair damaged tissue or…
› To allow an organism to grow.
This process of cell division doesn’t happen
randomly as you can expect.
 It is highly regulated and has distinct
features.
 As such, there are five main stages during a
cell’s life, during each of which specific
things happen.

These stages make up what is called the
cell cycle.
 The cell cycle is a repeating sequence
of cellular growth and division during the
life of a cell.
 Your job today is to discover what these
five stages are and identify the main
process that happens during each of
these stages.

Cell Cycle







Illustrate the cell cycle on a
piece of copy paper. These will
go into your notebooks but will
be for a grade. Check them off
with me for credit.
Use the drawing on page ______
(Cell Cycle) as your basis for
your poster. Use the pages of
the book to help describe the
steps.
Each Step of the cell cycle must
be correctly depicted on your
poster.
For each step you must include
at least 3 points and 1 drawing.
For Synthesis you must describe
the purpose of replication.
For Mitosis you must label the
goal.
Use color and check your
grammar.
Interactive Cell
 http://www.exploratorium.edu/traits/cell
_explorer.html

Interphase
 During interphase, the cell is not dividing. It is
growing, making proteins, metabolizing sugars and
other nutrients, and preparing to divide.
Different types of cells spend different amounts of
time in interphase dependent upon their roles in
the body.
 Cells that divide often, such as skin cells, spend less
time in interphase.

› Their job is more for protection & produce a shield, not to
produce proteins.

Cells that divide seldom, such as nerve cells, spend
most of their time in interphase.
› Their job is more for relaying information.
› Muscle and other tissue cells are in this category.
Interphase
 During the first gap phase (G1), a cell grows rapidly as
the cell builds more organelles and makes proteins. For
most organisms, this phase occupies the major portion
of the cell’s life as the cell performs most “life” functions
here (like transcription & translation… gene expression)

During the synthesis phase (S), a cell’s DNA is copied. At
the end of the S phase, the cell’s nucleus has twice as
much DNA as it did in the G1 phase.
 This, as you now know, is replication.

During the second gap phase (G2), the cell continues to
grow and prepares to divide. Hollow protein fibers
called microtubules are organized in the cytoplasm
during G2.
Only the nucleolus is visible
under a microscope.
The DNA is all spread out.
Cell Division
 In addition to duplicated DNA, each new cell requires
a complete set of organelles.
 This is accomplished in G2.
 The rest of the cell cycle is dedicated to dividing the
cell’s now-duplicated chromosomes and the
cytoplasm.
 The process of dividing the nucleus into two daughter
nuclei is called mitosis.

The process of separating the organelles and the
cytoplasm is called cytokinesis.

Identify and restate what the four stages
of mitosis are.

Identify when and why cytokinesis
occurs.
Vampire Mitosis
 You have learned that cells divide for
several reasons.
 You also learned about how DNA is
prepared before the cell divides.
 Today you will learn the process…What
happens through the life of a cell.

Only the nucleolus is visible
under a microscope.
The DNA is all spread out.

Remember, interphase is broken down
into 3 separate stages.
› G1: Cell Growth accomplished by making
new proteins.
› S: Replicating the DNA to go from 46
chromatids to 96 chromatids.
 Basically, doubling all the genes.
› G2: Doubling organelle and prepping the
DNA for cell division.

Although mitosis is a continuous process, biologists
traditionally divide it into four stages.
Mitosis is a continuous process that can be
observed in four stages:
 Prophase
 Metaphase
 Anaphase
 Telophase

Stage 1 Prophase
 1. Within the nucleus, chromosomes begin to
condense and become visible under a light
microscope.

2. The nuclear membrane breaks down. Outside
the nucleus, a special structure called 3. the
spindle forms. The spindle is made up of several
spindle fibers.

Each spindle fiber in turn is made up of an
individual microtubule—a hollow tube of protein.
Microtubules organize into a spindle that runs at a
right angle to the cell’s equator.
Stage 1 Prophase
 Cells have an organelle called the centrosome,
which helps assemble the spindle.

In animal cells, the centrosome includes a pair of
centrioles. Each centriole is made up of nine triplets
of microtubules arranged as a short, hollow tube.

4. Before mitosis, the cell’s centrosome is
duplicated. During prophase, the centrosomes
move to opposite poles of the cell.
› This gives 4 centrioles
Click to animate the image.
C
B
F
E
D
A
Identify the stage of
this Cell
Stage 2 Metaphase
 During metaphase, the chromosomes are
packaged into their most condensed form.

1. The nuclear membrane is fully dissolved, and the
condensed chromosomes move to the center of
the cell and line up along the cell’s equator.

2. Spindle fibers link to the centromere of each
chromosome.
Stage 3 Anaphase
 Once all of the chromosomes are lined up, 1. the
spindle fibers shorten. The spindle fibers shorten by
breaking down the microtubules bit by bit.

2. Sister chromatids move toward opposite poles as
the spindle fibers that are attached continue to
shorten.

Each pole now has a full set of n chromosomes.
Stage 4 Telophase
 1. A nuclear envelope forms around the
chromosomes at each pole of the cell.

2. Chromosomes, now at opposite poles, uncoil
and change back to their original chromatin form.

3. The spindle dissolves and the spindle fibers break
down and disappear.

Mitosis is complete.

As mitosis ends, cytokinesis begins. The cytoplasm is
separated, and two cells are formed.

During cytokinesis, the cell membrane grows into
the center of the cell and divides it into two
daughter cells of equal size.

Each daughter cell has about half of the parent’s
cytoplasm and organelles.

The end result of mitosis and cytokinesis is two
genetically identical cells in place of the original
cell.
Separating the Cytoplasm
 In animal cells ( and other cells that lack cell walls ),
the cell is pinched in half by a belt of protein
threads.
In plant cells and other cells that have rigid cell
walls, the cytoplasm is divided in a different way.
 In plants, cell division is accomplished by vesicles
creating a large, membrane-bound cell wall called
the cell plate.


Continuing the Cell Cycle
 After cytokinesis is complete, each new daughter
cell enters the G1 stage of interphase.

The daughter cells are about equal in size—about
half the size of the original cell.

The activity of each cell continues because each
has its own DNA and organelles. The cell cycle
continues for each new cell.
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Animal Cell
Plant Cell
Spindle fibers
Centrioles
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
IPMATC
I Play Music At The Concert
41
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



On the worksheet, complete the mitosis notes.
These are not word-for-word so work with your
group mates & come up with logical answers.
Skip & come back to those you can’t figure out.
Use the illustrations on the board to fill in the
ovals.
Use books!!!

How can you apply this?
› Your lab today will allow you to practice identifying cells in each
phase.
› The question you are trying to answer is how long does a cell
stay in each phase of the cell cycle?
› What does this mean about the life of a cell?
› First, predict how many hours a cell might spend in each phase
of the cell cycle.
• Onion Root Tip Lab
• Turn your sheet to
the side with the
picture so we can
try to determine 1
of each kind of cell
Decide which phase each numbered cell is.
IF YOU THINK THE CELL IS IN
1. Anaphase
CYTOKINESIS THEN COUNT IT
AS 2 CELLS IN INTERPHASE.
2. Interphase
3. Telophase
4. Prophase
5. Metaphase
3
1
5
IF YOU CAN’T TELL IT’S IN INTERPHASE
2
4
THIS IS DUE FRIDAY
THE NUCLEOLUS IS THE
FEATURE OF A CELL IN
INTERPHASE

The life of a eukaryotic cell cycles through phases
of growth, DNA replication, preparation for cell
division, and division of the nucleus and cytoplasm.

Mitosis is a continuous process that can be
observed in four stages: prophase, metaphase,
anaphase, and telophase.

During cytokinesis, the cell membrane grows into
the center of the cell and divides it into two
daughter cells of equal size. Each daughter cell
has about half of the parent’s cytoplasm and
organelles.
Look at the next 2 slides.
 Before you advance, try to fill in all the
blanks with the most reasonable answer.
 If you can do this without notes, you are
getting close to understanding the stepd
of the cell cycle.

Interphase
Stage:
Mitosis Notes
Name:_____________
Cell Cycle: The life of a eukaryotic cell cycles through 5
growth
synthesis preparation for
stages of __________,
DNA ____________,
Cell division
________
_____________ , and division of the nucleus &
cytoplasm
____________.
Interphase
1st -3rd _________________:
This phase has 3 stages:
G1 the cell grows rapidly as it builds
During ____
major
organelle
___________.
Most organisms spend the _______
S phase, a
portion
_________of
its life in this stage. During the ____
G2 phase, the cell
cell’s DNA is copied
______. During the ____
Divide
prepares to ________.
Mitosis
4th _______________:
4-step process of nuclear division.
condense and pair with their
Step 1: Chromosomes __________
membrane dissolves, the
homologue. The nuclear ________
spindle
_______ forms and centrosomes
________ move to opposite poles
_____.
Step 2: _______________
Cytokinesis
Mitosis
Metaphase
Step
Step 2:
2: _______________
_______________
equator
Condensed
Condensed____________
____________
lineup
upon
onthe
the__________.
__________.
chromosomes line
centromere ofofsister
Spindle
Spindle fibers
fibersattach
attachto
tothe
the____________
____________
sister
opposite
chromatid &
_________
poles.
_________
&link
linkthem
themto
to_____________
_____________
poles.
Anaphase
Step
Step 3:
3: ________________
________________
sister
_____________
__________
Spindle fibers
_____________
__________shorten
shortenand
andpull
pull_________
_________
___________
chromatid toward
___________
towardopposite
oppositepoles.
poles.
Telophase
Step
Step 4:
4: _________________
_________________
Once
_____________
Sister chromatid
Once the
the ____________
____________
_____________are
areatatopposite
opposite
poles
________________
Nuclear membrane
poles the
the ___________
___________
________________forms
formsatat
each
fiber
spindle
each pole.
pole. The
The__________
__________
fiberdissolves
dissolvesand
andthe
the
_______________
chromosomes uncoil
_______________
uncoiland
andchange
changeback
backtoto
______________.
chromatin
______________.
cytokinesis begins.
______________
isiscomplete
and
____________
Mitosis
______________
complete
and
____________
begins.
th
55th _________________.
The
____________
protein
belt
Cytokinesis
_________________.
The______
______
____________
grows
middle of
grows through
throughthe
the________
________
ofthe
thecell
celland
andititdivides
divides
into
_____________
Genetically identical
daughter cells.
into two
two ____________
____________
_____________
cells.