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Mitosis

Page history last edited by Charles Forstbauer 14 years, 2 months ago

Closed 1/14/10

Totaled 1/10/10 Mr F

Totaled 1/5 /10 Mr F

Totaled 12/22 Mr F

 

There are 7 phases of mitosis.

Interphase: DNA is replicated, and the cell does its "basic jobs"

 

Interphase is the phase of the cell cycle in which the cell spends the majority of its time and performs the majority of its purposes including preparation for cell division. In preparation for cell division it increases its size and number of organelles, and makes a copy of its DNA. Interphase is also considered to be the 'living' phase of the cell, in which the cell obtains nutrients, grows, reads its DNA, and conducts other "normal" cell functions. The majority of eukaryotic cells spend most of their time in interphase. Interphase does not describe a cell that is merely resting but is rather an active preparation for cell division. A common misconception is that interphase is the first stage of mitosis, however, since mitosis is the division of the nucleus, prophase is actually the first stage.

In interphase, the cell gets itself ready for Mitosis or Meiosis. Somatic cells, or normal diploid cells of the body, go through mitosis in order to reproduce themselves through cell division. Whereas diploid germ cells (i.e. primary spermatocytes and primary oocytes) go through meiosis in order to create haploid gametes (i.e. sperm and ova) for the purpose of sexual reproduction.

Prophase: Chromatin condenses into chromosomes which begin to move toward the cell center, chromosomes become visible, centrioles move to the opposite ends of the cell

Prophase, is a stage of mitosis in which the chromatin condenses into a highly ordered structure called a chromosome in which the chromatin becomes visible. This process, called chromatin condensation, is mediated by the condensin complex. Since the genetic material has been duplicated in an earlier phase of the cell cycle, there are two identical copies of each chromosome in the cell. Identical chromosomes, called sister chromatids, are attached to each other at a DNA element present on every chromosome called the centromere. During prophase, giemsa staining can be applied to elicit G-banding in chromosomes. Prophase accounts for approximately 3% of the cell cycle's duration.

Prometaphase: The nuclear envelope breaks down so there is no longer a recognizable nucleous.

Prometaphase is the phase of mitosis following prophase and preceding metaphase, in eukaryotic somatic cells. The nuclear envelope breaks into fragments and disappears. Microtubules emerging from the centrosomes at the poles (ends) of the spindle reach the chromosomes, now highly condensed. At the centromere region, each sister chromatid has a protein structure called a kinetochore. Some of the spindle microtubles attach to the kinetochores, throwing the chromosomes into agitated motion. Other spindle microtubules make contact with microtubules coming from opposite pole. Forces exerted by protein "motors" associated with spindle microtubules move the chromosomes toward the center of the cell.

Metaphase: The chromosomes are aligned in one "plane" of the cell, chromosomes are still duplicated chromosomes

Metaphase, is a stage of mitosis in the eukaryotic cell cycle in which condensed & highly coiled chromosomes, carrying genetic information, align in the middle of the cell before being separated into each of the two daughter cells. Metaphase accounts for approximately 4% of the cell cycle's duration

Anaphase: Chromatids get pulled apart/separate and begin to move toward the cells poles.

Anaphase, is the stage of mitosis when chromosomes separate in a eukaryotic cell. Each chromatid moves to opposite poles of the cell, the opposite ends of the mitotic spindle, near the microtubule organizing centers. During this stage, anaphase lag could happen.

Telophase: Chromatids arrive at the poles and the fibers that have pulled them apart prior disappear

Telophase, is a stage in both meiosis and mitosis in an eukaryotic cell. During telophase, the effects of prophase and prometaphase events are reversed. Two daughter nuclei form in the cell. The nuclear envelopes of the daughter cells are formed from the fragments of the nuclear envelope of the parent cell. As the nuclear envelope forms around each pair of chromatids, the nucleoli reappear. Telophase accounts for approximately 2% of the cell cycle's duration.

Cytokinesis: Spindle fibers continue to break down; the "contracile ring cleaves the cell into two daugher cells." New cytoskeletons are created for each cell to begin each one again in interphase.

Cytokinesis, is the process in which the cytoplasm of a single eukaryotic cell is divided to form two daughter cells. It usually initiates during the late stages of mitosis, and sometimes meiosis, splitting a binucleate cell in two, to ensure that chromosome number is maintained from one generation to the next. In animal cells, one notable exception to the normal process of cytokinesis is oogenesis (the creation of an ovum in the ovarian follicle of the ovary), where the ovum takes almost all the cytoplasm and organelles, leaving very little for the resulting polar bodies, which then die. In plant cells, a dividing structure known as the cell plate forms across the centre of the cytoplasm and a new cell wall forms between the two daughter cells.

To remember the phases, the phrase "I picked many apples to cook" (IP(P)MATC), or use IPMAT.

http://biology.about.com/library/blmitosisanim.htm -this animation shows how mitosis works in a really easy way. the animation is at the bottom of the page

 

Pictured above is a eukaryotic nucleus. Eukaryotic cells contain many organelles and chromosomal DNA. They are more complex than prokaryotic cells, which do not go through elaborate replication processes or have as intricate organelles.

 

 

cancer: a disorder in which some of the body's own cells lose the ability to control growth \

 

 

 

picture of cancerous cells

This picture represents the Mitosis process with all the major phases included.

 

 

10.2 Cell Division

 

·         chromatid- one of two identical “sister” parts of a duplicated chromosome

·         centromere- area where the chromatids of a chromosome are attached

·         interphase- period of the cell cycle between cell divisions

·         cell cycle- series of events that cells go through as they grow and divide

·         mitosis- part of eukaryotic cell division during which the cell nucleus divides

·         prophase- first and longest phase of mitosis, during which the chromosomes become visible and the centrioles separate and take up positions on the opposite sides of the nucleus

·         centriole- one of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope

·         spindle- fanlike microtubule structure that helps separate the chromosomes during mitosis

·         metaphase- second phase of mitosis, during which the chromosomes line up across the center of the cell

·         anaphase- the third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles

·         telophase- fourth and final phase of mitosis, during which the chromosomes begin to disperse into a tangle of dense material

·         cytokinesis- division of the cytoplasm during cell division.......>>

 

·        

During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells, each of which then begins the cycle again.

·         Biologists divide the events of mitosis into four phases: prophase, metaphase, anaphase, and telophase.

 

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--This video explains the process of mitosis in depth. It helped me visualize and put all the stages together. 

 

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this video is great for explaining to process of mitosis. The graphics are really good. 

 

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this is a rap of mitosis it is catchy and easy to understand

 

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this video shows real cells going through mitosis. it is really cool to see. 

 

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this video gives great in depth discriptions of all of the steps of mitosis

 

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this is a synchronized swimming video of the stages of mitosis. it's really fun to watch and helps you vizualize the process 

 

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This video was made by a student so its easy to understand and fun to watch. 

Interphase - During interphase cellular organelles double in number, the DNA replicates and protein synthesis occurs.

 

Prophase - Thoe chromatin condenses and the chromasomes become visible. Also the nucleous disappears, the nuclear membrane fragments and spindle fibers are assembled.

 

Prometaphase - The stage in mitosis following prophase, and before metaphase in which the nuclear membrane breaks into fragments and dissapears, the centrioles reach the poles of the cell and the chromosomes continue to contract.

 

Metaphase - The nuclear membrane fragmentation is complete and the duplicated chromosomes line up along the cell's equator

 

Anaphase - Diploid sets of daughter chromosomes move toward opposite poles of the cell and cytokinesis begins

 

Telophase - The nuclear membrane and nucleoi reform, cytokinesis is nearly complete and the chromosomes eventually uncoil to chromatin. This phase is the reverse of prophase and prometaphase

 

Difference between Mitosis and Meiosis:

 

Mitosis and Meiosis describes the process by which the body prepares cells to participate in

either asexual or sexual reproduction to make an entire organism.

 

Examples of Mitosis and Meiosis:

Mitosis is the reproduction of skin, heart, stomach, cheek, hair etc. cells. These cells are "Autosomal" cells. This is also a form of "Asexual" reproduction, where one organism or cell reproduces itself. Some organisms that reproduce asexually are hydra, bacteria, and single celled organisms.

"A" greek meaning "without."

"Sex" Greek meaning "to cross."

Meiosis is the production of sperm and egg cells. These cells are "Gamete" or "Sex" cells. Each cell has to go through the division process twice in order for the cell to end up with half the number of chromosomes. The cells pass on genetic information to the offspring. This is a form of "Sexual" reproduction, where one organism or cells reproduces by crossing with another organism or cell. Types of organisms that reproduce sexually are; plants, animals, and insects.

  • For either of these processes of reproduction we must first understand the basic Chromosome structure that the body uses in either Mitosis or Meiosis.

 

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This is a very simple video showing how meiosis occurs. It also explains the process that are unique to meiosis, I found this to be very helpfull in differenciating it from mitosis.

 

 

Mitosis: -- One cell becomes two cells-- The new "daughter" cell has exactly the same number of chromosomes and information as the "parent" cell. 1 cell divides and becomes 2 cells.

 

 

Meiosis: -- One cell becomes 4 cells--There are 4 new "daughter" cells. Each new gamete cell contains only one-half of the number of chromosomes of the parent cell. Each sex cell goes through the division process twice in order to have the correct number of cells, and the correct chromosomal information. (Look carefully at the diagram below to understand how each chromatid becomes part of a new sperm or egg cell. Go back to the first diagram if necessary to study what a chromosome pair, chromatid, and allele is.)

In female mammals (humans too) 3 of the gametes do not mature with a full yoke sack. Only 1 of the 4 can become a mature egg. All mature eggs are formed to a certain stage in the first division.

In male mammals (humans too) all 4 gametes mature into sperm cells. The male is continually forming these after birth.

 

 This diagram is a simple quick summary of the difference between mitosis and meiosis. I found it helpful in understanding the difference because it brakes it down into the stages for you can gives an explantion about how its different and what's happening.

 

 

This diagrammatic representation of mitosis shows the cell undergoing a full cycle of division to produce two daughter cells.

Diagramatic Mitosis

Cell Size 

  Finally, at some point, there is just enough surface available to service all the interior; if it is to survive, the cell must stop growing.

 

Surface Area to
Volume Ration
The important point is that the surface area to the volume ratio gets smaller as the cell gets larger.

Thus, if the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume. When this happens, the cell must divide into smaller cells with favorable surface area/volume ratios, or cease to function.

That is why cells are so small.

 

 

Purpose of mitosis:

 

Mitosis is the process of cell division, and occurs only in "somatic" or body cells. When haploid sperm meets haploid egg, a chain of events that begins with a single diploid cell and ends with an adult organism made of billions of cells is set in motion. The single cell divides into 2, and each of those 2 divide again, and this process continues geometrically along the following progression: 1, 2, 4, 8, 16, 32, 64, 128, and so on into the billions. Therefore, the first purpose of mitosis is growth. The second function of mitosis is repair. Cells are constantly wearing out and getting damaged and unless an organism replaces them at least as fast as they are lost, a gradual deterioration will occur. 

1. tissue growth ( growing new tissue )

2. regeneration ( the process of replacing tissue )

3. asexual reproduction ( one cell divides, the whole organism reproduces ) also known as cloning

 

Another reason that mitosis occurs is to maintain an efficient and expedient system of nutrient absorbance among all the cells in a body. When cells grow to be very large, the surface area necessary to diffuse nutrients into the cell is sacraficed to a greater volume. Volume grows at a rate much faster than surface area. It is for this reason that cells must continuously divide to keep for losing their efficiency, ensuring the survival of the particular cell.  

Mitosis under a microscope

 

 

In Relation to the lab we did during class when we looked under a microscope at an onion cell, this diagram helps guide you in what you should be seeing. This diagram may help the counting of the stages because you can see what the stages look like under a microscope with this diagram.

 

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Here is another video on the process of mitosis.

 

 

STUDY HELP 

http://biology.about.com/od/mitosis/a/aa121704a.htm

This link is a quiz that you can take on the stages of mitosis. It's a nice quick quiz to check and see if you know what you're talking about.  

 

 

This diagram breaks down the process of mitosis similar to other diagrams above but in a decending order. this helps organize the pictures to fit the IPMATC structure we are trying to memorize for the test tomorrow.

 

 

Each phase of Mitosis is shown in the diagram followed with a brief description of what occurs in each phase, which is helpful when trying to memorize what exactly occurs in each phase. 

 

 

this is a clear picture of all of the phases in mitosis

 

Cancer

*        Cancer arises from the mutation of a normal gene.

 

*        Mutated genes that cause cancer are called oncogenes.

 

*        It is thought that several mutations need to occur to give rise to cancer

 

*        Cells that are old or not functioning properly normally self destruct (apoptosis) and are replaced by new cells.

 

*        However, cancerous cells do not self destruct and continue to divide rapidly producing millions of new cancerous cells.

*       Benign tumors do not spread from their site of origin, but can crowd out (squash) surrounding cells eg brain tumor, warts.

 

*       Malignant tumors can spread from the original site and cause secondary tumors. This is called metastasis. They interfere with neighbouring cells and can block blood vessels, the gut, glands, lungs etc.

 

*       Why are secondary tumors so bad?

 

*       Both types of tumors can “tire” the body out as they both need a huge amount of nutrients to sustain the rapid growth and division of the cells.

 

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html

^ Copy and paste this link into your URL. 

This is a very helpful and simple way of understanding mitosis without getting too in depth or lack there of.

 

This is a link to the webquest we did:

http://www.cellsalive.com/mitosis.htm

It clearly shows and explains the phases of mitosis. 

 

http://staff.jccc.net/PDECELL/celldivision/mitosis1.html

This link is very helpful in explaining the process of mitosis, and all of its phases to the reader. The website that it comes from is also helpful for various other biology-related topics.

 

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This video is really interesting because it shows real images of a cell during mitosis, so it helps to be able to tell the difference between each phase visually.

 

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This video has pictures and words, which helps to easily understand each phase.  The song playing in the background makes the video fun and easy to pay attention to, unlike a lecture. [Hey- you'll get your chance to deliver a lesson soon! Mr F]

 

This is a really great photo of mitosis and what it really looks like during each of its stages. (reads top, left to right; bottom, left to right.)

 

 

 

Here is a video I made about the mitosis process for review for the test:

Fliqz has shut down their service. To access this video, email support with this video id: 41509710e8924044baf97689fa2be8ed

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This video was made by a group of high school students.  The video is really corny, but it does help with remembering funny ways to remember the differences between each stage of mitosis.

 

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This is a stop motion video of prophase, which is helpful and easy to understand.  The video shows the chromatin condensing well.

 

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This video was created by the same person who made the video above, so it is a stop motion video.  However, this video contains all of mitosis rather than just prophase.  This video also includes guiding words to make the concept incredibly easy to understand.

 

 

 

Mutation- A mistake that can occur diring DNA respiration or protein synthesis Through this picture of a mutation it is obviouse that the mutation has reproduced and has caused a new trait to be expressed:

 

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