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Cell Growth and Division Notes
Limits to cell growth
 The larger a cell becomes, the more demands on its DNA
 Trouble moving enough nutrients and wastes across the cell
 Organization!
What effects do the following have on the cell?
Surface area:
Effects the rate of food, O2, H2O, and wastes moving in & out of the cell
Effects the rate at which food, O2, H2O are used and waste is produced
Ration of Surface area to Volume:
As the cell gets bigger the volume increases faster then ____surface
The decrease in the SA/V ration makes it difficult for the cell to:
Before we talk division
Genes located in DNA within _____Nucleus_____________of eukaryotic cell
DNA strand wraps around proteins to form thin threads called
When cell gets ready to divide, DNA duplicates, then condenses into
Humans have ____46__________________________ chromosomes in every cell
During __S-phsase_____of the cell cycle, all 46 are copied (making an identical
copy of the original DNA)
NOW when the cell splits in half, each new cell has _
the exact same number of
Anatomy of a Chromosome
After Synthesis (S) phase,
each chromosome
consists of two identical
________sister chromatids_____________
– Chromatids attached at
Cell Division
When a cell divides the __Chromosomes_____stays the same.
Common locations for cell division in a mature adult human
1. Intestinal Lining
2. Skin
3. Sperm Cells
4. Liver-sometimes
Cells that stay in G0 (non-dividing) once mature
1. Muscle Cells
2. Cardiac Cells
3. Kidney
4. Nerve Cells
The Cell Cycle
G1 (gap 1 phase)-Checks DNA is ok to duplicate
S (Synthesis Phase)-DNA is copied
G2 (Gap 2 Phase)-checks DNA that is replicated is healthy
M (M phase)-Chromosomes are properly attached to spindle fibers
Checkpoints and Apoptosis
As the cell goes through Cell cycle there are
What happens if a cell is stopped at a checkpoint?
Repair the damage
Self destruct (apoptosis)
MITOSIS--- Nuclear division
The movements of chromosomes are guided by _____spindle fibers_________
during mitosis.
Interphase --- NOT A PART OF MITOSIS this is really:
. Interphase: “I-ball”
90% of the time!
1. Gap 1: cell grows, doubles organelles
2. Synthesis: duplication of the DNA in
the cell's chromosomes
3. Gap 2: cell grows, microtubules assembled
The Steps of Mitosis (PMAT)
1. Prophase
2. Metaphase
3. Anaphse
4. Telophase
1. Prophase – “Pasta”
 Chromatin fibers ____CONDENSE__________________________________
 _____NUCLEAR____membrane breaks down
 Spindle of microtubules forms from centrioles [Animals_only]
 Spindle fibers attach to chromatids on __centromere___________________
2. Metaphase- “middle”
 Chromosomes ___________line up____________ in the middle
 Spindle fibers attach _____centrioles____to centromeres
 Every ____sister____________ Chromatid_____has fiber attached to
3. Anaphase: “_________Away_______ ______Phase______”, form “A’s”
 _______Spindle___________ ____Fibers________________ contract
 Pull sister chromatids _____apart___________________
 The __Chromosomes____continue to move until they are in
_______two __________groups
 Each side has own copy of DNA
4.. Telophase- “end phase”
 ____________Nuclear_____membranes reform at each pole
 Chromosomes ___unwind_______________________
 Spindle ___disappears__________________
 ___NOT A __a phase of Mitosis
 During cytokinesis, the cytoplasm _cuts in half
 Each daughter cell has an _______identical______set of duplicate chromosomes
Cytokinesis in Plants
In plants, a structure known as the ________cell plate___________________ forms midway
between the divided nuclei.
Cytokinesis in Animals
Animal cells contract an ___actin fiber across middle of cell and “pinch” into
___________2___________ new cells (daughter cells).
A. Spindle: network of microtubules that move chromosomes during
mitosis and meiosis
B. Equator: center line of cell where chromosomes line up during
C. Poles: The opposite ends of the poles
D. Centrioles: animals cells ONLY, move the spindle and chromosomes
During division.
D. Cleavage Furrow: The pinching in of animal cells during cytokinesis
F. Cell plate: disk in plant cells that divide the cell into two daughter
Cells during cytokinesis.
G. Centromere: region where two sister chromatids are joined tightly
Results of Mitosis
A. Production of 2 new _____daughter________cells
B. Daughter cells are ____exactly_______ the same as original
C. Cell --> Tissue --> Organ --> Organ System --> Organism
Contact Inhibition
- Normal cells will reproduce until they ____contact_____other cells.
- When this happens, they ____stop growing___.
- Controls on cell growth and division can be turned ___on and off____
Proteins that control Cell Cycle and growth
 Cell cycle regulated proteins called _cyclins_________________________
The amount and type rises and falls in time w/ the cell cycle
 Cyclin: because it regulates cell ___cycle___________________
Regulate the timing of cell cycle in eukaryotic cells
Cancer is: a disorder in which some of the body's own cells lose the ability
to control growth.
 Cancer is a disorder in which some of the body’s own cells lose the
ability to control growth
 Lose the ability to do their job
How are cancer sell different from other cells
Cancer cells do not respond to the signals that regulate the growth of most
 Divide uncontrollably
 Don’t stop at ___Checkpoints___ and do not do
 Form masses of cells called _____tumors________________________
 ____Metastasis____: tumor cells break loose and spread in body
Causes of Cancer: Carcinogens
 Genetics
 Chemicals- asbestos, cigarettes,
formaldehyde, dioxins, chlorine, pesticides
 Radiation
 Certain viruses (HPV)
 Poor Diet/ Obesity
Prevention of Cancer
 Genetic screening BRCA 1 and BRCA 2
Do not smoke, drink too much, proper
diet, exercise, prevent sunburns, proper
health screenings