Jeremy's Blog

I was only in class 3 days this week. One of the two days was spent taking a quiz so we only had two good working days. We finished up with cell reproduction and started on multi cellular reproducrion. We learned that there are 46 chromosomes in a human body. When we reproduce, we give 23 of the 46. By getting half the chromosomes from each parent it makes every person look and act different. If every person got the full DNA from their parents, every person would have double the DNA and would explode from having too much info in their bodies. There are two sex chromosomes out of the 46. X and Y or X and X. If a person has two x's they will be a girl. If a person is a boy they will have an x and y. The other 44 chromosomes are autosomes which control all other things. Anything that differs between boys and girls if found in x and y. The others determine things that doesn't matter between boys and girls like hair and eye color.

Now we started getting into meosis. We started to look at a simulation of meosis. The first things we noticed was that it is almost idntical to mitosis. The biggest difference is meosis makes four cells by dividing twice. The DNA is not replicated inbetween the two divisions so you end up with 4 cells with 23 chromosomes. Before the proccess starts tetrads, or groups of four chromosomes form. In the tetrad some of the genes go the the other side of the tetrad.

In my own reaserch I learned that in meosis sperm and egg cells are formed. The proccess only happens in animals because of this. All of the phases of mitosis are present in meosis. The same things happen in each phase in meosis as in mitosis except Prophase. The difference is each phase happens twice.