Download The Cell Cycle - Biology with Mrs. Flores

Unit #6 - The Cell Cycle
• The white sections summarize key information and
vocabulary terms are underlined.
Dreams
I look to the sky and what do I see?
A castle, a rainbow, and dreams for me,
An end to this battle that I must fight,
To rid my feelings of depression and fright,
An end to cancer is not far away,
It will be here someday... someday.
~ Anonymous
Observations
Introduction
Textbook Reference pg. 204-206
• Much as your body goes
through different stages in
your life, the cells and viruses
do too.
• The life cycle of the cell is
known as the cell cycle.
• In this unit we will discuss the
processes of the cell cycle
(the making of new cells).
http://www.wadsworth.org/BMS/SCBlinks/
mcewen/Media/fig_1_cell_mitosis.jpg
5 Reasons Cells Divide
Textbook Reference pg. 203
1. Growth- an organism will increase in size as the
number of cells making up that organism increase
2. Differentiation- cells develop specialized cells to
carry out specific tasks
ex: the heart cell versus the muscle cell
3. Repair- to repair lost or damaged cells
ex: mending of skin, blood vessels and bone
4. Regeneration- ability to replace a lost limb or body
part by rapid cell division ex: starfish, lizard
5 Reasons Cont.
• And finally…
5. Reproduction – the making of a new organism
http://ghr.nlm.nih.gov/handbook/illustrations/mitosismeiosis;jsessionid=B368026AB01
E981849F2E31603F7154F
Cell Division
• The splitting of a single cell into two new daughter cells
is called cell division.
• This will occur when a cell reaches it’s maximum size
and the nucleus initiates cell division; proteins called
cyclins and enzymes begin this process.
http://protist.i.hos
ei.ac.jp/PDB/Ima
ges/Sarcodina/H
eliozoa/Actinosph
aerium/cell_divisi
on_1.jpg
Two Types of Cell Division
Textbook Reference pg. 204-206
• Mitosis- the division of
body cells (somatic) due
to the splitting of the
nucleus to create two
new cells.
• Meiosis – the creation of
gametes (sex cells) by
cutting the # of
chromosomes in half to
create sex cells.
http://ghr.nlm.nih.gov/handbook/illustrations/mitosi
smeiosis;jsessionid=B368026AB01E981849F2E3
1603F7154F
Chromosomes
Textbook Reference pg. 203-204
• In order for a cell to survive, the
genetic information is needed.
• Cells tightly coil their DNA into
chromosomes during the
process of mitosis.
• Review: We have already
learned that genetic information
is held within the nucleus (of
Eukaryotes) in the form of DNA.
• Therefore, it is very important
that cells must copy their
genetic information before
dividing.
http://www.koshland-sciencemuseum.org/exhibitdna/images/
dna/intro02.gif
Chromosomes Cont.
http://www.learner.org/channel/courses/biology/images/archive/fullsize/1940_fs.jpg
Chromosomes Cont.
• During mitosis, identical
chromosomes pair up and
are now called sister
chromatids (1), held
together by a centromere
(2).
• Sketch it!
http://upload.wikimedia.org/wikipedia/e
n/5/54/Chromosome.png
Stage #1
Interphase
Textbook Reference pg. 204-205
1.
•
http://dedunn.edublogs.org/files/2011/06/mi
tosis-26hzktr.jpg
•
•
Interphase = The period of
growth for the cell before cell
division (the longest stage)
which is broken up into the
following phases:
G1 – growth and
development
S – copies of the DNA
G2 – the cells organelles and
centrioles (in animals only)
copied
Knowledge Check
During the course
of the life of a
cell, there is a
complicated series
of checkpoints to
ensure that
everything is
going according to
plan.
Textbook Reference pg. 206-208
2.
•
•
Prophase = The DNA
condenses and forms
chromosomes.
Identical chromosomes
(Xsomes) join
Nucleus disappears
• Centrioles (the organelles which form the spindles)
move to opposite poles
• Spindle fibers (long strings that help the cell divide)
begin to grow
http://dedunn.edublogs.org/files/2011/06/mi
tosis-26hzktr.jpg
Stage #2
Prophase
Stage #3
Metaphase
Textbook Reference pg. 208
3.
•
Metaphase =
Xsomes pairs line
up along the middle
of the cell on the
the metaphase
plate
Centrioles have
moved to the poles;
spindle fibers are
still attached to
chromosomes.
http://dedunn.edublogs.org/files/2011/06/mitosis26hzktr.jpg
Metaphase Cont.
http://student.ccbcmd.edu/courses/bio141/lecguide/unit6/genetics/DNA/DN
Arep/images/metaphase1_pc.jpg
Stage #4
Anaphase
Textbook Reference pg. 208
http://dedunn.edublogs.org/files/2011/06/mitosis-26hzktr.jpg
4.
•
Anaphase = The centromeres divide and spindle fibers
pull the chromosomes apart from their partners
The chromatids move to opposite poles of the cell
Stage #5 Telophase
Textbook Reference pg. 209
5.
•
•
•
Telophase = The
nuclei reform at each
end of the cell
Chromosomes uncoil
into chromatin (or
loose genetic material)
Spindles release
Xsomes and shorten.
The cell begins to
pinch as the cytoplasm
begins to divide
http://dedunn.edublogs.org/files/2011/06/mitosis26hzktr.jpg
Stage # 6 Cytokinesis
Textbook Reference pg. 209
6.
•
•
•
•
•
Cytokinesis = In animals, the cell
membrane is drawn inward (cleavage
furrow).
In plants, a cell plate is built to create
new cells walls and membranes.
Each half has one nucleus and gets
own set of centrioles (and other
organelles)
The cell is pinched in half until
membrane meets.
The cell is now two and enters
Interphase (G1).
Animation
http://alevelnotes.com/content_image
s/i77_dwa_1_mitosis.gif
Cytokinesis Cont.
•
“During mitosis, after all the genetic material is sorted
out, the cell splits all of its cytoplasmic goodies in two
and sends them to opposite ends. It then constricts in
the middle and eventually ‘pinches’ in half, producing
two daughter cells. The location at which the pinching
in occurs is known as the cleavage furrow.” Image
Visualizing Mitosis
Anaphase
Prophase
Interphase
Metaphase
http://wiki.district87.org/images/9/9f/Plant_cells.jpg
Telophase
Ex Mnemonics
• Ms. Flores’s Example:
I = “I’ll
P = probably
M = make
A = apple
T = tarts for
C = Christmas!”
• Student Created Example:
I = “Intelligent
P = people
M = make
A = all
T = the
C = cash!”
• The word “mnemonic” means “memory tool”. It
is a phrase or saying to remember a list.
• Student Created Example:
I = “Irritating
P = pupils
M = make
A = all
T = teachers
C = cringe!”
•
The mnemonic goes on the outside of the flap
and the actual stage goes on the inside of the
flap.
http://buffonescience9.wikispaces.co
m/file/view/Mitosis-Animation1.gif/294684052/236x228/MitosisAnimation-1.gif
In Conclusion
• At the beginning of the unit, we discussed how cancer
relates to mitosis.
• Cancer is thought to be caused by a change in the
controlling genes that regulate the cell cycle.
• Mitosis is the division of somatic body cells to create
identical daughter cells.