chapter 10: cell growth and division -...
TRANSCRIPT
Chapter 10: Cell Growth and Division
Limits to Cell Growth
1. DNA “overload”- the larger the cell, the greater demand it places on its DNA
2. Exchanging materials- the larger the cell, the more trouble it has enough oxygen and nutrients in and waste products out
3. Ratio of Surface Area to Volume: cell volume increases more rapidly than surface area causing the ratio of surface area to volume to decrease
4. Cell Division: before a cell becomes too large, it divides into 2 daughter cells each with a complete set of DNA; it also solves the problem of increasing size by reducing cell volume
Chromosomes-made of DNA
• Chromatids: copies of chromosomes (each replicated chromosome has 2)
• Centromere: connects the 2 sister chromatids
The cells of every organism have a specific number of chromosomes.
• Humans have 23 pairs of 46 total chromosomes
The Cell Cycle
Interphase: consists of 3 parts G1 Cells grows
S DNA replication
G2 many organelles & molecules required for division are produced
https://study-biology.wikispaces.com/file/view/mitosis_stage.png/
4 phases (PMAT)
Prophase: • centrioles appear &
move to opposite ends of the cell
• Spindle fibers form • Nuclear membrane
breaks down
Centrioles
Spindle Fibers
Nuclear Membrane
Metaphase
• Chromatids attach to the spindle fibers at the centromere
• Chromosome line up across the center of the cell
Anaphase
• Sister chromatids separate into individual chromosomes
• Chromosomes move to opposite ends of the cell
Telophase
• 2 nuclei form • Chromosomes
uncoil • 2 nuclear
membranes form
Cytokinesis: cytoplasm splits in half
Animal Cells Plant Cells•Cell membrane pinches inward until cytoplasm is split into 2 equal parts
•A cell plate forms between the 2 nuclei • It eventually develops into a cell wall
Regulating the Cell Cycle !
• Controlled by different genes• Proto-oncogenes stimulate cells to divide • Tumor supressor genes prevent cells from
dividing uncontrollably
Uncontrolled Cell Growth
• When genes that regulate the cell cycle are damaged, cells divided uncontrollably
• Tumors (a mass of growing tissue) can be benign or malignant
https://thetruthaboutcancer.com/benign-malignant-tumors-difference/
http://www.aicr.org/cancer-research-update/2014/october_01/cru_Report-Half-of-Cancer-Deaths-are-Preventable.html
http://cancerprogressreport.org/Slides/Fig04_CPR15.jpg