This has been bugging me for a long time- what's the difference between miosis and mitosis?

Meiosis is the division of cells to form gametes (egg and sperm cells). Mitosis is the division of cells to form somatic cells and cells of the central nervous system.

Meiosis is the essence of sexual reproduction, which was a huge advance over mitosis from the perspective of Darwinian evolution.

The key element of meiosis is "crossing over" of chromosomes, whereby the genes get reshuffled during gamete formation, so that the offspring get an unpredictable combination of genes from each parent. That way each offpsring of the same two parents is unique.

This allows way more genetic variation compared to simple binary fission (mitosis, or "cloning," with its only occasional mutations). In turn, natural selection wouldn't be very effective without all the underlying genetic variation resulting from sexual reproduction based on gamete formation by meiosis.

This is a very common question. As a HumBio teacher, I've learned to give the basics first and let my students' amazing brains go from there.

I posted the main differences on the following site. I even used this forum as a source!!!

http://www.comparati.com/132-Meiosis-vs-Mitosis

quote:

Meiosis is the division of cells to form gametes (egg and sperm cells). Mitosis is the division of cells to form somatic cells and cells of the central nervous system.

The problem with Curious123's post is that it didn't have the prometaphase in the graphic. the correct order is...

Iterphase- organelles are being duplicated and the cell grows in size
Prophase- duplicate chromotids are formed and pair up. centrosomes(in the cytoplasm) start to microtubules and the nucleoi start to disappear.
Prometaphase- The nucleus envelope breaks and the centrosomes move toward the "polar" ends of the cell
Metaphase- The chromotid are lining up across the "equator" and the centrosomes are at polar opposites.
Anaphase- the microtubules attach to the chromotids ad a point of protien located at the connection site or "belt" of the chromotids and are starting to pull them apart.
Telophase and Cytokinesis- at the center of the cell, a tightening at the middle like a belt occurs and the duplicated chormosomes each settle into the opposite sides. The nucleonic membrane is forming around both sets of DNA and new organelles form as the cell divides along this "belt area" resulting in 2 new cells. (same process for plants but instead of the membranes "belt effect" a new cell wall is built.

In Miosis, there are double the amount of steps excluding the prometaphase and instead of 2 exact copies of the original cell, the number of chomosomes is halved and there is a result of 4 new cells. Also, meosis only occurs in sexual cells... sperm and ova. Hope that was a little "clearer" lol