Wednesday, November 10, 2010

reflections for Trimester 1

This is what I learned about macromolecules, cells, and cell division. I learned that proteins are made up of amino acids held together by peptide bonds.I learned that lipids are not polymers. I learned that carbohydrates have a chemical formula C6H12O6. I learned that enzymes have the ability to speed up reactions. I also learned about plasma membranes of cells and how some substances are allowed to pass through freely while others are not. The membrane is made of a phospholipid bilayer that regulates the passage of substances in and out of the cell. Within the membrane are organelles that control and regulate processes of the cell. Mitochondria deal with cellular respiration and produce ATP, lysosomes have digestive enzymes that break down food for the cell or even other organelles, and ribosomes produce protein. I also learned about cell division in meiosis and mitosis. Mitosis occurs when a cell duplicates its genetic material, forming two identical copies, and then proceeds to divide into two daughter cells. Meiosis however forms 4 haploid daughter cells, where mitosis creates only 2 diploid cells.
What I have found difficult is bonding. Hydrogen bonds, peptide bonds, and basically any type of bond is somewhat confusing for me. The bonds in lipids seem to be rather weird to me also.
Biological systems regulate in many ways. The whole process of mitosis involves several crucial checkpoints to make sure everything is dividing correctly and at the right time. There is a checkpoint at the end of the G1 phase before it goes into the S2 phase. This checkpoint is there in order to ensure that all the organelles and cytoplasm have divided and that their is enough for each cell to function independently. This is one of many ways that biological systems regulate.