Transcript mitosis

Chapter 10
Cell Growth & Division
10-1 Cell Growth
• Limits
– The larger a cell becomes, the more demand it
places on the cell’s DNA.
– The Cell has more trouble moving enough
nutrients & waste across the cell membrane
• Surface Area-to-Volume Ratio
– Volume increases much faster than surface area.
– Causes the surface area to volume ratio to
decrease.
• Cell Division
– A cell will divide into 2 “daughter
cells” before it becomes too large.
– Before Cell Division occurs, the cell
must copy all of its DNA.
– This gives each “daughter cell” an
exact copy of the original cell’s
DNA.
10-2: Cell Division
Chromosomes Made of DNA (Carries genetic
information)
1. Only visible during cell division.
2. Copied before the cell divides.
3. When visible, each chromosome consists of
2 identical sister chromatids.
4. Attached in the center by a centromere.
Before Replication
After Replication
Centromere
Chromosomes
Sister chromatids
The Cell Cycle
A. Interphase
1. G1 Phase-Cell
growth
2. S-phase- DNA
replicates
3. G2 Phase- Prepare
for Mitosis
B. M-Phase
1. Mitosis
a. Prophase
b. Metaphase
c. Anaphase
d. Telophase
2. Cytokinesis
• Cytokinesis- division of the cytoplasm
– Animal cells-cytoplasm pinches in
until 2 cells are formed
– Plant cells- cell plate forms midway
between the divided nuclei.
(Eventually becomes the cell wall)
10-3 Regulating the Cell Cycle
• Controls on cell division
– Cells at the edge of an injury are
stimulated & divide rapidly
– Division slows down when the
healing process ends.
Cell Regulators
• Internal Regulators
– Proteins that respond to events inside
the cell.
– Cyclins-regulate the timing of the cell
cycle in eukaryotic cells.
• External Regulators
– Direct cells to speed up or slow down
the cell cycle.
Cancer
• A disorder in which some of the body’s own cells
loose the ability to control growth.
• Change in 1 or more of the genes controlling the
production of enzymes involved in the cell cycle.
– Expressed as cancer when environmental
factors trigger the damaged genes into action.
– Forms masses of tissues called Tumors that
deprive normal cells of nutrients & can damage
the surrounding tissue.
Cancer Cont.
• Final Stage– Cancer cells enter the circulatory system, spread
throughout the body, forming new tumors that
disrupt organ function.
• Enzymes– Monitor the cell’s progress from phase to phase
of the cell cycle.
– Can trigger or inhibit the progression of the cell
cycle.
Cancer Cont.
• Contact inhibition– Cell-to-cell communication to know when to stop
dividing.
Normal Cells- Have Contact Inhibition (know when to
stop dividing)
Cancer cells- Loose ability of Contact Inhibition (do not
realize the are in contact with each other and continue to
divide).
• Normal Cells
• Cancer Cells