Scibepost for October 13, 2010 by Amreen M(=

Today we had shortened classes because of late arrival, so for 35 minutes, Mr. Paek taught us about Mitosis and we took notes. He also gave us a worksheet with some of the notes and pictures of the stages of mitosis.

First, he explained that the reason we don't have a bunch of big cells in our body is because with small cells, theres more surface area in terms of volume so its easier for gases to get exchanged.

Mitosis-the life cycle and division of a cell

Mr. Paek explained to us that interphase, which are the three big parts of this cycle, takes much longer then metaphase, which are the four small parts. Interphase has three parts: the G Phase, S Phase, and the G2Phase, and it basically is preparing the cell to divide. During interphase, the individual chromosomes cannot be distinguished and appears as a dark mass of material called chromatin.

Interphase- Each chromosome is replicated, consisting of two identical "sister" chromatids; the DNA of each chromosome replicates at the end of this stage.

After he explained Interphase for a couple minutes, he went on to mitosis, which has four stages. Phrophase, Metaphase, Anaphase, and Telephase. Mr. Paek said that when he was learning the cell cycle in school, he used an anagram called IPMAT, which stands for Interphase, Prophase, Metaphase, Anaphase, and Telephase. These stages are also in order.

Prophase-The stage when chromatin condsenses into chromosomes, centrioles seperate, spindle fibers form, the membrane gets broken, and the nuclear envelope disapears. This is a picture of a cell in the prophase stage.You can tell its in the phrophase stage because the membrane has holes in is and is beginning to break.

Metaphase-The chromosomes line up at the center of the cell. Each chromosome is connected at the centromere to the spindle fibers.

Anaphase-The paired chromosomes split into individual chromosomes and are moved apart.

Telephase- The chromosomes gather at opposite ends of the cell and then split. The spindles are broken apart, the nuclear envelope reappears, and the nucleus divides

We also briefly talked about Cytokinises, which takes place after Telophase. Cytokinesis is when the cytoplasm pinches in half and each daughter cell has duplicate chromosomes. Here is picture summing up everything:

After we were finished taking notes, Mr. Paek let us watch the Last Lecture for the last two minutes of class. Our homework is to read, highlight, and complete page 40-43 in our Unit Packet. These pages are our Mitosis Pre-Lab for the lab that we will be doing tomorrow

The next scriber is..MALIHA!=D