Meiosis

In Meiosis there are alot of certain things that are different than Mitosis. Mitosis is for cell reproduction and each cell is made exactly the same. In Meiosis genes and traits are the difference. No two things created by Meiosis are exactly the same and this is very interesting. It makes sure that nothing is the same. That makes flowers the way they are, people the way we are, and animals the way they are. There are also 5 main steps in Meiosis but you'll see the difference is my explanations and diagram below.

Prophase I
Nuclear division is about to occur in the first phase. A spindle forms as centrosomes move away from each other. The nucleolus disappears and so do the nuclear envelope fragments. Homologous chromosomes both have two sister chromatids and have to go through synapsis to make bivalents. The exchange of color may occur over the nonsister chromatids After this happens the sister chromotids are no longer identical.

Metaphase I
The bivalents held together by chiasmata have moved towards the equator of the spindle. This is determined by a fully formed spindle and alignment of the bivalents at the equator of the spindle.Protein complexes on the outside of the centromeres are called Kinetochores and should be seen by now. These are attached to spindle fibers. The bivalents align themselves at the equator of the spindle. Then the maternal and paternal homologues may be oriented on either pole. This means that all possible combinations can occur in the daughter cells.

Anaphase I
The homologues of each bivalent seperate and move to opposite poles. Each chromosome still has two chromatids.

Telophase I
Creates divisions so that each daughter cell has one chromosome from each homologous pair. Each parent has two pairs of homologous pairs of chromosomes. After telophase we get into Interkinesis. This is when mitotic division is similar to Interphase except DNA replication does not occur because chromosomes are already duplicated.

Mitosis

There are two main ways of cell reproduction which are very different from each other. Mitosis uses 5 different phases to make an exact copy of the cell. For example if you tear a muscle then your brains tells the cells to start reproducing so the tear will heal. I'm sure you don't want bone cells where the muscle needs fixed. Meiosis is a completely different thing with having 7 steps instead of 5. Meiosis can only be used in one thing and that is sexual reproduction. Anything living uses this to make more of it. In Meiosis no two things are exactly the same and that is the beauty of it. I will talk about Meiosis in my next blog.

Mitosis is made up of 5 different steps and here is more detail about them.

Interphase
This is the starting phase when the cell is doing its normal job. New DNA is split up so that each chromosome has equal amount of DNA. The two chromosomes are called duplicated or replicated chromosomes and attach in a structure called the centromere. After time the cell gets ready to start Mitosis by putting together much of the things needed to move chromosomes around. Although interphase really isn't a part of Mitosis it is something important to know about.
Prophase
This is the first step in Mitosis and involves the chromosome to become visible. This is done by paired centrioles (centrosomes) moving to opposite ends of the cell. To tell that its no longer interphase the nucleoli disappear and inside the nucleus is grainy like spaghetti. As the centrosomes move apart the mitotic spindle forms. Some of the fibers of the mitotic spindle attach to chromosomes pulling them towards the center of the cell.


Metaphase
In metaphase the centromeres are now in the center of the cell. Many nonattached spindle fibers are visible in metaphase. Some of these fibers reach beyond the metaphase plate and overlap.

Anaphase
Sister chromatids part and become daughter chromosomes that move toward the spindle poles. Each daughter cell has a centromere and a single chromatid that appear to move to opposite poles. Each pole receives the same number and kinds of chromosomes. This cell is called the parent cell.

Telophase 
During this phase daughter cells that have the same chromosomes as the parent cell form as nuclear envelopes and nucleoli reappear. Chromosome will become indistinct chromatin.

In this experiment I had to choose which phase each picture was in out of 36 pictures. The highest # of pictures was Interphase with 20 pictures. Going from highest to lowest the next # of pictures were Prophase with 10 pictures. Next down was Metaphase with 3 pictures. After Metaphase was Anaphase with 2 pictures. Finally with 1 picture was Telophase. I think it was funny that the phases went in order with the last phase as the lowest # of pictures and Interphase with the highest # of pictures.

The questions from the lab are in the link below

https://docs.google.com/document/pub?id=1VkdM64evQlortXHTTNlCBvAcCc9M8rvkUzkyooWDe2E