Your+Cells,+My+Cells,+Everybody's+Cells+3

cells are there? ||  || media type="youtube" key="SceSaMusM48" width="425" height="350" ||
 * ||  || ===The Cell -Part 3 === ||
 * How many
 * ===The head of a pin is about 2mm in diameter.===
 * ===The head of a pin is about 2mm in diameter.===

In turn,bacteria and viruses are even smaller.
||  ||  Here you can see a human hair If you then magnify it you can see a few other things

until.......... ..... you can see the smallest magnified cell || || pairs, called autosomes,look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females. Females have two copies of the [|X chromosome], while males have one X and one [|Y chromosome].
 * How many chromosomes are in a human body? ||  || In humans, each cell normally contains 23 pairs of chromosomes,for a total of 46. Twenty-two of these

The 22 autosomes are numbered by size. The other two chromosomes, X and Y, are the sex chromosomes. This picture of the human chromosomes lined up in pairs is called a karyotype.

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 * How do cells divide? ||  || =How do cells divide?=

There are two types of cell division: mitosis and meiosis. Most of the time when people refer to “cell division,” they mean mitosis, the process of making new body cells. Meiosis is the type of cell division that creates egg and sperm cells. Mitosis is a fundamental process for life. During mitosis, a cell duplicates all of its contents, including its chromosomes, and splits to form two identical daughter cells. Because this process is so critical, the steps of mitosis are carefully controlled by a number of genes. When mitosis is not regulated correctly, health problems such as cancer can result. The other type of cell division, meiosis, ensures that humans have the same number of chromosomes in each generation. It is a two-step process that reduces the chromosome number by half—from 46 to 23—to form sperm and egg cells. When the sperm and egg cells unite at conception, each contributes 23 chromosomes so the resulting embryo will have the usual 46. Meiosis also allows genetic variation through a process of DNA shuffling while the cells are dividing. || Learning by mrs.gratton
 * Links:

Your cells, my cells, everybody's cells

Your cells, my cells, everybody's cells2 ||  || by: Shannon Schoettle+ Laura Utner ||