Science First week after Christmas 1/9

This week was kind of awkward because we were discossing reproduction and its difference from sex. The first thing we wanted to do was clarrify the difference between the two things. We only want to learn about reproduction. Reproduction is the sperm meeting with the egg cell. We knew how mammals and some other animals reproduced, but we did not know how cell reproduce. A living thing grows because cells are reproducing. Cells reproducing is the basic part of human reproduction.

We had two theories on how cells reproduce.One theory we had was that cells reproduced with a sperm cell and egg cell. But this didn't make sence because a single cell would not produce a sperm cell and an egg cell just to make one cell. Also, we knew cells reprodused as one not as two, unlike humans. Our other theory was that cells split themselves in half from one mother cells into two daughter cells.

Wecame up with certain things that must happen in cell reproduction.DNA must be copied because otherwise the cells would not look the same and they would each only have half the DNA the original cell had. Another problem was having each cell have all of the organelles such as mitochondria and ribosomes. We thought that that the cell may create double the amount of each organelle it has. The last problem we saw was if a cell splits in half, it makes two cells half the size the origonal. This would cause the organism not to grow. We decided that the cells must grow at some point in their life.

We learned that the Cell does copy its DNA and reproduce in a prosses called mitosis. The steps of mitosis are Prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis. In prophase DNA is copied and the nucleus begins to fade. In Prometaphase the nucleus is gone and there is only chromosomes. Metaphase is when the chromosomes align in the center of the cell. Anaphase is when spindle fibers connect to the kinetochores and start to pull the chromosomes apart from their copies to the poles of the cell. In telophase the chromosomes form two nuclei at the poles of the cell. In the last step cyokinesis, the cell separates into two separate cells.