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Cell Cycle & Mitosis Notes
Essential
What is the relationship of the process of mitosis to the growth of organisms and to
Question:
repair of damaged cellular materials?
Activating
Strategy:
Quickwrite: when cells multiply they make more of themselves and also when cells
divide they make more of themselves
What are the 3 limits for cell size?
1. Diffusion-is the fast efficient over short distances but slow and inefficient over
long distances.
2. DNA limits cell size-cells need A LOT of proteins to perform critical functions
BUT there is a limit to how quickly DNA can be made into proteins.
3. Surface area to volume ratio-as a cells size increases, its volume increases much
faster than its surface area.
What are the reasons for cell division?
a. maintaining optimum cell size
b. growth in multicellular organisms
c. asexual reproduction of single celled organisms
d. to produce dead cells
Chromatin vs. Chromosomes
Chromatin is long strands of DNA wrapped around proteins
Chromosomes coiled strands of DNA that look like X’s; becomes like this just before
cell division.
Cell Cycle
During which phases does a cell spend most of its time? interphase
During S the DNA is copied.
Mitosis is the process in which a cells nucleus is divided into 2 new nuclei. Each new
nuclei have the same kind and number of chromosomes as the parent. This is also
called asexual reproduction.
The cell cycle follows the following format.
1. Interphase (DNA replication)
2. Mitosis (which is broken into four phases)
a. Prophase-nuc.env.dissappears chromosomes
b. Metaphase-chromosomes (X’s) line up in the middle of the cell. Spindle fibers
attach to the centromere on the chromosomes. Spindle fibers are produced by the
centrioles
c. Anaphase-spindle fibers begin to pull the chromosomes (X’s) apart. Chromatid
(V’s) now move toward opposite ends
d. Telophase- chromatid (V’s) reach the poles. Nuclear envelope begins to reappear
around the chromatid. In plant cells a cell plate appears down in the middle to divide the
cell. In the animal cells a cleavage furrow appears to separate the cell.
Mitosis pictures: identify which is each phase:
Anaphase
Cytokinesis
Chromatid
Telophase
3. Cytokinesis- the production of 2 new identical daughter cells from the splitting of the
cell’s cytoplasm.
Mitosis
Result is 2 identical daughter cells.
It is how unicellular organisms reproduce.
In multicellular organisms, cell growth and division results in a group of cells that work
together.
Cell → tissue → Organ → Organ System → ORGANISMS
Cancer
Enzyme control each phase of the cell cycle. Enzymes are proteins.
Cancer is the result of uncontrolled cell growth.
Extra mass of cells is called tumors.
Causes of cancer are both genetic and enviromental( UV rays, smoke, and viral
infections).