The Process of Mitosis Essay

     More than one celled organisms grow by way of mitosis and the cytoplasmic division of body cells. On the other hand, meiosis occurs only in germ cells, which are put aside for the formation of gametes (sperm and egg). Reproduction by meiosis allows for species survival and it increases genetic variability.

a) As before follow instructions in the handout and draw pictures for each stage of Meiosis I an Meiosis II – color!

Out of a total from 26 sequences only 6 were made up of 4‘s while 20 were composed of different structures of 2‘s. This tells us that 77% of the asci showed crossing over while 23% did not.

According to the data table, prophase is the longest stage of mitosis. Even though there were more tallies in the interphase section, interphase is not considered a stage of the mitotic cycle; it is more or less considered a stage in the cell cycle. Telophase is the shortest stage because there were very few cells that showed evidence of them actually being in this stage. Metaphase and anaphase are intermediate stages, with metaphase being longer than anaphase.

At prophase the chromosomes become condense to become visible and the membrane begins to break down. The chromosomes line up along the centre of the equator during metaphase. The chromatids separate and are pulled to opposite poles during anaphase. In telophase these separate chromatids

Mitosis and meiosis are similar in several ways and different in others. The similarities include that both processes involve IPMAT. IPMAT is interphase, prophase, metaphase, anaphase and telophase. The parent cells are diploid. They both end with cytokinesis. In Metaphase and Metaphase II, the sister chromatids line up along the center. Then in Anaphase and Anaphase II, these chromatids are split and pulled towards the centrosomes. The differences are that mitosis consists of 1 division while meiosis consists of 2. Four genetically different, haploid sex cells are the products of meiosis and 2 identical, diploid somatic cells from mitosis. Mitosis occurs in all organisms except viruses and meiosis only occurs in plants, animals, and fungi.

2. In which phases of mitosis are sister chromatids visible, and attached to each other at the centromere?

Although mitosis is just a fraction of time compared to interphase it can be divided into four distinct subphases. If we start viewing a cell under a brightfield microscope right at the end of interphase subphase G2 we would see that throughout the interphase process (fig 1) the cell has grown considerably in size due to production of extra mitochondria and endoplasmic reticulum. The cell has also gone through the labor of duplicating all of its chromosomes, a process known as DNA synthesis. Now that the cell has made all of these preparations it's time to start prophase (fig 2), the first stage of the mitotic phase. This stage is visibly identified by the chromatin becoming the tightly formed chromosomes. During the lab we were able to view these newly formed chromosomes best on the onion root tip

D. The kinetichore is the site of attachment of the centromere to the nuclear spindle apparatus.

Find a representative cell for each stage of mitosis on the onion slide and draw a clear diagram of the different phases you observed in the accompanying space. Be sure to draw only what you see, but include all details that are visible. Your drawings will not necessarily look exactly like the ones in Figure 3A, 3B, 3C.

Page 18: The fairy excitedly began to say the next phase of this wonderful process is prophase. In this process the “chromosomes become thicker and the chromosomes form into a spiral”. Sam asks the fairy, “ Could you tell me what interphase is again?”

19) The phase of mitosis during which the nuclear envelope fragments and the nucleoli disappear is called

Mitosis is one of two main methods of cell replication, the other being meiosis. It is “the simple duplication of a cell and all of its parts” resulting from the splitting of a cell. The ‘parent’ or original cell splits, duplicating its DNA (packaged in chromosomes) producing two ‘daughter’ or new cells with the same genetic code. There are four stages of mitosis; Prophase, Metaphase, Anaphase and Telophase. Interphase is not an official phase of mitosis as the cell is at ‘rest’ and not being divided during this phase. It is often called one of the phases of mitosis as it is one of the stages in the life cycle of a cell; however it is not a phase of mitosis due to the fact that no division takes place.

B. Original diagram of the different levels of protein structure (i.e., primary, secondary, tertiary, and quaternary).

The main focus of this lab was to be able to understand the different phases of mitosis and the cell cycle and also identify what those stages may look like. Mitosis is the process in which concerns the production of new cells. For example, when apoptosis(cell death) the process of Mitosis begins to replace the dead cells. To be able to familiarize ourselves with this concept, we took a sample of an onion root and had it put through a process to be able to look at the different phases under the microscope. We found that the majority of the cells were mostly undergoing Interphase or Prophase which are the phases in charge of crossing over of DNA and where the chromosomes then become visible and the nuclear envelope dissipates. The conclusion of this lab was that Mitosis is essential for the production of new cells. In the case of the onion root sample, the cells were damaged leading to the tester to undergo Mitotic cell division and it was found that mainly Interphase and Prophase were the stages that occurred in this lab.