Meiosis Lab

This week in AP Biology we did a lab over meiosis. In the lab we had red and pink beads and a yellow magnet. With these things we had to make chromosomes and make an illustration with the beads to make them look like they are in interphase, prophase, metaphase, anaphase and telophase in mitosis and also the exact same but in meiosis. After that we had to get cards with a picture of crossing over. We had to count how many were in a 4:4 ratio or 2:2:2 ratio and so on and so forth. Once that was done, we would then have to find the percentages of ratios. The final thing we did was on the first day we started the lab, we put onion pieces in sand soaked in water and let them sit in a drawer for a few days, so the onions will start to grow tips.  We would then cut the tips and put them on a microscope slide with hydrochloric acid on the onion tip and then put it over a flame for 5 seconds. Once that was finished we had to put this special substance on the onion tip ( I forgot the name of it :(  ) and put it over a flame for about 2 minutes. We would then put it under a microscope a look to find the stages of interphase, prophase ,metaphase, anaphase and telophase.



  

Meiosis

This week in AP Biology we discussed about meiosis. Meiosis is a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in production of gametes and plant spores. Meiosis has two cell divisions, Meiosis I and Meiosis II. Meiosis I halves the number of chromosomes, while in Meiosis II, sister chromotids split.  Just like mitosis, meiosis goes through Prophase, Metaphase, Anaphase, Telophase, and Cytokensis, but these phases produce gametes and to simply make you, you. In Interphase I, DNA replicates and each chromosome becomes doubled.In Prophase I, crossing over occurs which makes two homolougous chromosomes line up next to each other. Once crossing over occurs, the chromosomes are no longer identical. In Metaphase I, homologous chromosomes line up along the equator of the cell. In Anaphase I, chromosomes pull apart from opposite ends of the cell. In Telophase I, the spindle fibers disintegrate and cytokinesis begins. Once cytokinesis is complete, Meiosis II begins. Meiosis II is very similar to mitosis. In Prophase II, the spindle fibers start to form. In metaphase II The chromosomes line up and each cell has only one of each homologous chromosome. In anaphase II, the sister chromotids move away from each other and in telophase II and cytokinesis, the formation of four genetically different haploid cells form.

The Cell Cycle

This week in AP Biology we talked about the cell cycle. The cell cycle is the life of a cell from the time it is first formed from a dividing parent cell until its own division into two cells. Without the cell cycle, our body would not be able to function how it does. Such as when you get a cut, it eventually heals because of mitosis.There are seven phases in the cell cycle. G1, Interphase, S, G2, Mitosis, M, and Cytokinesis. Each phase has a different job. In G1 the cell grows while carrying out cell functions unique to its cell type. In S phase the cell continues to carry put its unique functions. it also duplicates its chromosomes. The G2 phase is just the gap after the chromosomes have been duplicated and just before mitosis. Mitosis is a type of cell division that generates new cells for growth and repair. Cytokinesis is the division of the cell's cytoplasm. In the M phase, cell division occurs for a short amount of time the contents of the nucleus are evenly distributed to two daughter nuclei, and the cytoplasm divides in two. The other phases are Prophase, Metaphase, Anaphase, Telophase. In Prophase the chromatin becomes more tightly coiled into discrete chromosomes. In Metapahse, The microtubules move the chromosomes to the metaphase plate at the equator of the cell. In Anaphase, Sister chromatids begin to seperate, pulled apart by motor molecules interacting with kinetochore microtubules. In Telophase the nuclear envelopes re-form around the sets of chromosomes located at opposite ends of the cell. The cell cycle is a very important process to humans and animals. Without it, our body will not be or act how it does now.