Musings

For all you numerous readers who were worried about me because I didn’t post- its not because I don’t love you.
Just had a biology test.  Pretty rough.  There was quite a time constraint, and I had to do the last page in 2 minutes right before the bell.

So, anyway, I’m going to my brothers holiday performance tonight.  Gotta do all my homework fast.

Back to biology and mitosis and stuff.  Ok, so mitosis is normal nuclear division, remember?  There are four phases of mitosis- prophase, metaphase, anaphase, and telophase.

The first part, prophase, starts with the loosely packed DNA condensing in to chromosomes, which are essentially big blobs of DNA and protein.  Many chromosomes look a bit like a capital X.  Each half of the X is called a chromatid.  Both chromatids in a chromosome are identical. Little fibers called the spindle also form.  These will help the chromosomes move into the right places and also support the cell.

Next, during metaphase, some of the spindle fibers attach to either end of the cell (called the poles).  Others attach the chromosomes to the poles.  These fibers, called kinetochore fibers, move the chromosomes into the center, or the equator, of the cell.

Then comes anaphase.  The chromatids separate, with one from each chromosome going to either end of the cell.  Again, the kinetochore fibers aid in this movement.

Last in mitosis is telophase.  The spindle fibers dissolve, and the chromosomes decondense back into DNA.  The cell prepares for the cellular division, called cytokinesis.  But that’s next time.

Till next time,

Dr. Harry Bear

Cell Division

School sucked. Except for biology. Cause its FUN!!

Anyways, I’m having fun doing biology homework. We get to look at cells tomorrow. Isn’t that fun??

Soy muy sarcastico cuando hablar de la escuela. Translate that yourself, you lazy bum!

But really, biology is fun.

Today’s science lesson will pertain to cell division in eukaryotes. It is a general overview, and will be followed up with the steps of mitosis and meiosis in the next couple of posts.

Mitosis and meiosis are two different types of cell division. Mitosis happens in most of the cells in our body that divide. Basically, one cell divides into two daughter cells. Each pair of chromosomes is copied, and one copy of each pair (two chromosomes) is sent to each daughter cell.  The two daughter cells are exactly the same genetically as the parent cell (except for a few mutations).

Meiosis is the type of cell division that produces sex cells (yes, sperm and eggs). Most cells have two copies of each chromosome, but cells that have been produced by meiosis only have one copy of each chromosome. This allows the zygote produced by the merging of the sperm and the egg to have a full set of chromosomes.

That will take a while to chew on.

Till next time,

Dr. Harry Bear