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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?
Mitosis creates new cells. Those new cells add to the existing organism by replacing
damaged cells and making bigger organs to support a growing organism.
Activating
Strategy:
Quick write:
I think that the statement “Biology is the only subject in which multiplication
means the same thing as division” means that when you multiply in biology you are
also dividing. It isn’t like Math where you multiply two things and get a higher
number and when you divide two thigs you get a lower number. For example when
cells divides to create new cells they multiply when creating more.
What are the 3 limits for cell size?
1. Diffusion- is fast and efficient over short distances but slow and inefficient over
long distances. Cells would die before nutrients could reach the organelles
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 cell’s 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 replace dead cells
Chromatin vs. Chromosomes
Chromatin is long strands of DNA wrapped around proteins(tangled up spaghetti)
Chromosome 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 phase___ 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
-first step of cell cycle
-the preparation phase
-three stages: G1, S, and G2
2. Mitosis (which is broken into four phases)
a. Prophase- first stage of mitosis. Nuclear envelope begins to disappear. Chromatin
(spaghetti/long strands of DNA) coils up and become X-shaped chromosomes.
b. Metaphase- chromosomes (X’s) line up in the middle of the cell. Spindle fibers
attach to the centromere on the chromosome. 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 the middle to divide the
cell. In animal cells a cleavage furrow appears to separate the cell
Mitosis pictures: identify which is each phase:
_Metaphase_
_Telophase_
_Prophase_
_Anaphase__
3. __Mitosis____________- 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 → __tissues_____ → 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 ___environmental_____ (UV rays, smoke,
and viral infections).