Mitosis!

Cell Replication: making two from one. So now that we know what chromosomes are and where to find them let's talk about cell replication (AKA mitosis). This is a rapid process that takes place in nearly all the tissues in your body and is happening right now! It is also how your bones, nails, and hair grow, and how you make new skin when you get a cut, etc.

(1) So usually your cells are going about minding their own business, making proteins, and have your 46 chromosomes all relaxed and kind of looking like a mess. But! When a signal comes and tells the cell that it needs to divide a cascade of events is triggered.

(2) First, you're going to need more chromosomes (to make sure the new cell also has 46). So, your cell starts to make identical copies (now called sister chromatids). These "sisters" are then linked together at the centromere (think of it like the chromosome holding hands, so they go through the process together).

(3) Second, the 23 pairs of "sisters" meet up in the middle of the cell to be divided up. This helps ensure that the new and old cell gets one "sister" from each pair. The "sisters" are pulled apart back into individual chromosomes again by spindles, and the cell breaks into two complete cells.

(4) Each cell is now identical to the original cell and can carry on producing proteins and keep us alive! There are flaws in this process, and errors do happen, but our cells have a cool checking mechanism that helps to pick up on mutations and other problems.