chapter 10: mitosis cell growth and division. cell division cell division – cell divides into two...
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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)
CHROMOSOMECHROMOSOME
centromerecentromere
sistersister chromatidchromatid
sistersister chromatidchromatid
MitosisProphase 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
Spindlemicrotubules 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.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120073/bio14.swf::Mitosis%20and%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
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