Although life originally started with mitosis, a biological need for meiosis still arose. Mitosis originally began before meiosis, because the organisms that are needed to reproduce were much smaller and less complex. On the other hand, meiosis is sexual reproduction. We need meiosis because it would be very important if we only had mitosis, then the cells would never "change". This is due to the fact that meiosis takes a random combination of genetic material from both parents while mitosis only splits the parent cell into two identical copies. The process of meiosis produces a total result of four cells that each contain different genes. Even though meiosis is the way humans that reproduce, mitosis is still used in humans to repair it. Now, your body uses both processes, mitosis, for internal repairing, and meiosis, to produce sex cells.
In this 3-class lesson, we reviewed about the skeletal system, circulatory system, immune system, cardiovascular system, and respiratory system. I learned about how 2 connected neurons and a neuron connected to a muscle is different because in 2 connected neurons there is a synapse/gap in between the connection of the neurons. In the neuron connected to a muscle the neuron is connected directly to the muscle with no synapse or gap in between the two
After viewing the video, I have learned that one cell has many kinds of functions such as pleasure feeling, pain feeling, frighten feelings, etc. Humans have thermal receptors, movement receptors, and low threshold. The thermal receptor detects when you touch something below human temperature or above human temperature. The movement receptor detects the feeling of when a bug crawls on your arm which moves the hairs around which then lets you know there is something on your arm. The low-threshold receptor detects when you are feeling pleasuring feelings.
One thing I learned in this three-class lesson is about some cell called macrophage. Macrophages kill and eat up other cells called antibodies that don't belong in the body. It reads each cells DNA and if there is one that doesn't match to your DNA then that antibody gets eaten. This process is called phagocytosis and basically kills antibodies by eating them.
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May 2014
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