The Cell Cycle
The steps eukaryotic cells
progress through during their
lifetime.
Cell size surface area and volume
Cells are very small. Why?
As a cell grows the volume increases and the
amount of surface increases.
However, the amount of surface area does not
increase enough to match the greater volume
allowing all needed materials to enter and exit
the cell.
New cells, why do we need them?
Every day 50 to 70 billion cells die in
your body from aging, this is called
programmed cell death and injury.
The Cell Cycle and cell division. Ch. 8
We need cells to grow*
To make Repairs
To replace old cells, like skin and Red
blood cells.
Some single celled organisms, like bacteria
and protists reproduce by cell division
The Cell Cycle*
Mitosis is nuclear division
Cytokinesis is Cell division
Cell Division
Restriction Points*
Cancer*
Causes.why cells cant stop dividing
U.V light
Chemicals, mutagens
X-rays
Replication errors
Viruses
Cancer
Wutation in Proto-oncogenes
create oncogenes.
Mutation ot tumor supressing
genes.
Mutations that may lead to cancer.
https://science.education.nih.gov/sup
plements/nih1/cancer/activities/activit
y2_animations.html
Watch cell cycle animations 1, 2, 3, 4 and 5
Be sure to note how cancer is related to Protooncogenes and tumor suppressor genes!!!
Be ready to discuss them.
Mitosis
A cell must create two identical
nuclei before it divides.
Chromosome number must stay
the same.
The creation of the two nuclei is
called mitosis.
Mitosis, is nuclear division*
The period between cell divisions.
Cells are actively doing their
specific functions.
Mitosis may occur at the end of
Interphase if the cell is destined to
divide
Interphase
Steps of mitosis
Prophase
Metaphase
Anaphase
Telophase
There are 4 steps in nuclear division
Each phase of mitosis is
described in the next
several slides.
Read each slide for a description.
Prophase, nuclear membrane and nucleolus
disappear. The replicated chromosomes condense
and become visible. The centromere holds the two
copies together, The spindle begins to form.
Metaphase, Sister chromatids attach to the spindle, at the
equator of the cell. The spindle is a network of fibers the
chromosomes will travel down when they separate.
Anaphase, the centromere
breaks and the chromosomes
separate and move towards two
poles
Telophase, 2 nuclei begin to reform, the spindle dissolves,
nucleolus reforms, chromosome uncoil, then cell divides by
cytokinesis [cell plate in plants, cleavage furrow in animal cells]
DNA replication
Replication enzymes
Proofreader enzymes locate damaged DNA.
Damaged DNA removed
DNA Polymerase adds new nucleotides A-T C-G
Ligase seals the sugar phosphate gaps
DNA repair

http://www.sciencekids.co.nz/videos/biology/m
itosis.html
View the Video
How to view cells undergoing mitosis
Onion root cells have areas of rapid cell division
Interphase, the phase between cell divisions
when cells doing their normal function.
Use the 2 root section handouts. Not
Label each cell with an I, P, M, A, T
Count up the number of cells in each phase.
Shsare your counts with the class.
Enter your data and class data into the table.
Calculate the % for each phase.
Answer the 5 questions and make the pie chart.
Mitosis lab
Lab Activity
Get a prepared slide and on a microscope find the
four stages of mitosis, draw each stage in your lab
book.
Conunt the # of prophase ___ metaphase ___ anaphase ___
telophase ___ interphase ___
Conunt the # of prophase ___ metaphase ___ anaphase ___
telophase ___ interphase ___
Conunt the # of prophase ___ metaphase ___ anaphase ___ telophase
___ interphase ___
Conunt the # of prophase ___ metaphase ___ anaphase ___ telophase
___ interphase ___
Conunt the # of prophase ___ metaphase ___ anaphase ___ telophase
___ interphase ___