I have been a very bad blogger lately! I have been working on so many projects for Biology they all kind of just take turns getting worked on. The good news is that I have made progress and finished some stuff on Mitosis and Meiosis. The following is a link to a glog I did on Mitosis:
http://sierra3.edu.glogster.com/glog-6479-4769/
I decided since I do Glogs for EVERYTHING! I would take a break and do an "old fashion blog post" and just tell you a little bit of what I learned on Meiosis.
First of all, what is Meiosis? Meiosis is the type of nuclear division that reduces the chromosome number from the diploid number to the haploid number, in sexually reproducing organisms. The total number of chromosomes is referred to as the diploid number. The haploid number still refers to chromosomes. But the haploid number of chromosomes is half of the diploid number. For example, in humans, the diploid number is 46. In the haploid number, you end up with 23. Gametes are the reproductive cells, often times this refers to the sperm and egg. Gametes usually have the haploid number of the chromosomes. When these gametes form and fuse they make a cell called a zygote. This is all part of the integral parts of sexual reproduction. A zygote always has the full number of chromosomes, the diploid number. In meiosis there are two unique cell divisions. Meiosis I and Meiosis II. Prophase, Metaphase, Anaphase, and Telophase are the phases of both Meiosis I and II. Crossing over occurs in Prophase I. Crossing over is very important. It is the exchange of genetic material between NONSISTER chromatids of a bivalent. Due to this swapping of material, the chromatids held together by the centromere are no longer identical. That means that when those chromatids during Meiosis II, separate, some of those daughter cells will receive chromosomes with recombined genes. The offspring will have a different sequence of alleles, due to genetic recombination. What does that mean? It means that they will have different genes than their parents. Making them, their own person. At the end of Meiosis I the two daughter cells will have one chromosome from each homologous pair. The chromosomes still consist of two chromatids. In Meiosis II, the chromosomes align at the metaphase plate and then the sister chromatids separate and become DAUGHTER chromosomes. In Telophase II spindle disappears, nuclei form. And then cytokinesis takes place. At the end of Meiosis we have four haploid daughter cells. After Meiosis II, the haploid cells become gametes in animal cells and spores in plants. And you know the rest already, those gametes form and fuse to make the zygote! For humans, Meiosis occurs only in the reproductive organs to make the gametes.
So there you go! A little bit of information on Meiosis. Very soon, I will be posting blogs on the things we have been working on more recently. Chapin, Sidney, and I are all working on our Eugenics post and it should be up soon! I will also have a blog on a case study very soon :)
