Transcript Cell Growth and Division

Chapter 10:
Mitosis
Cell Growth and Division
Cell Division
• Cell Division – cell divides into two new
IDENTICAL “daughter cells”
• Mitosis – division of nucleus during
eukaryotic cell division
• Cytokinesis – division of cytoplasm during
eukaryotic cell division
Cell Cycle
Interphase
• Interphase
– portion of cell cycle between divisions
– ~ 75 – 80% life of cell
– 3 phases:
• G1: cells grow and develop
• S: chromosomes replicate
• G2: organelles required for division
reproduce
Chromosome
• Chromosome
– located in nucleus
– contains DNA
• Chromatid
– half of chromosome
that has been
replicated
– pair of
“sister” chromatin
• Centromere
– area where each pair of
chromatids attach
(in center)
CHROMOSOME
sister
chromatid
centromere
sister
chromatid
Mitosis
•
Prophase  Metaphase  Anaphase  Telophase
“Please Make Another Test”
1. Prophase
– doubling of chromosomes & organelles
– centrioles visible
•
2. Metaphase
– chromosomes line-up in the middle
– spindles from centrioles connect to each chromatid (half of chromosome)
•
3. Anaphase
– chromatids are pulled apart to separate ends
– membrane begins to pinch off in the middle
•
4. Telophase
–
–
–
–
Nucleus and nuclear envelope reform
Chromosomes decondense and disappear (you can no longer see them)
Cytokinesis - complete division of cytoplasm
two daughter cells formed
Prophase
-DNA condenses into chromosomes
-Nuclear membrane begins to break down
- centrioles & chromosomes visible
Metaphase
- chromosomes line-up in the middle
- spindles from centrioles connect to each chromatid
Spindle
microtubules
that help
separate
chromosomes
Anaphase
- chromatids are pulled apart to separate ends
- membrane begins to pinch off in the middle
Telophase
-Each set of chromosomes is positioned at each end
of the cell
-Chromosomes begin to uncoil & spindles far apart
- two daughter cells formed
Cytokinesis
- cells “pinch” off from one another
- cytoplasm divides
http://highered.mcgrawhill.com/olcweb/cgi/pl
uginpop.cgi?it=swf::5
35::535::/sites/dl/free/
0072437316/120073/
bio14.swf::Mitosis%2
0and%20Cytokinesis
Regulating the Cell Cycle
•
Cyclins
– Proteins that stimulate division during
growth and repair (Interphase)
– Internal regulators
•
respond to the events inside the cell
– External regulators
•
speed up or slow down the cell cycle
Cancer
• Cancer = uncontrolled cell growth
– do not respond to signals that regulate growth
– causes: heredity, chemicals, radiation
• Tumors = unregulated cell growth
– Benign: cells stay together
– Malignant: cells spread and grow elsewhere
- invade healthy tissues