CELL DIVISION
Introduction: Cells divide for many reasons. For example, when you skin your knee, cells divide
to replace old, dead, or damaged cells. Cells also divide so living things can grow. When
organisms grow, it isn't because cells are getting larger. Organisms grow because cells are
dividing to produce more and more cells. In human bodies, nearly two trillion cells divide every
day.
How Many Cells are in Your Body?
You and I began as a single cell, or what you would call an egg. By the time you are an adult,
you will have trillions of cells. That number depends on the size of the person, but biologists put
that number around 37 trillion cells. Yes, that is trillion with a "T."
Depending on the type of cell, there are two ways cells divide—mitosis and meiosis. Each of
these methods of cell division has special characteristics. One of the key differences in mitosis
is a single cell divides into two cells that are replicas of each other and have the same number
of chromosomes. This type of cell division is good for basic growth, repair, and maintenance. In
meiosis a cell divides into four cells that have half the number of chromosomes. Reducing the
number of chromosomes by half is important for sexual reproduction and provides for genetic
diversity.
MITOSIS CELL DIVISION
Mitosis is how somatic—or non-reproductive cells—divide. Somatic cells make up most of your
body's tissues and organs, including skin, muscles, lungs, gut, and hair cells. Reproductive cells
(like eggs) are not somatic cells.
In mitosis, the important thing to remember is that the daughter cells each have the same
chromosomes and DNA as the parent cell. The daughter cells from mitosis are called diploid
cells. Diploid cells have two complete sets of chromosomes. Since the daughter cells have
exact copies of their parent cell's DNA, no genetic diversity is created through mitosis in normal
healthy cells.
Mitosis cell division creates two genetically identical daughter diploid cells.
The mitosis cell cycle
Before a cell starts dividing, it is in the "Interphase." It seems that cells must be constantly
dividing (remember there are 2 trillion cell divisions in your body every day), but each cell
actually spends most of its time in the interphase. Interphase is the period when a cell is getting
ready to divide and start the cell cycle. During this time, cells are gathering nutrients and energy.
The parent cell is also making a copy of its DNA to share equally between the two daughter
cells.
The mitosis division process has several steps or phases of the cell cycle—interphase,
prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis—to successfully
make the new diploid cells.
Introduction: Cells divide for many reasons. For example, when you skin your knee, cells divide
to replace old, dead, or damaged cells. Cells also divide so living things can grow. When
organisms grow, it isn't because cells are getting larger. Organisms grow because cells are
dividing to produce more and more cells. In human bodies, nearly two trillion cells divide every
day.
How Many Cells are in Your Body?
You and I began as a single cell, or what you would call an egg. By the time you are an adult,
you will have trillions of cells. That number depends on the size of the person, but biologists put
that number around 37 trillion cells. Yes, that is trillion with a "T."
Depending on the type of cell, there are two ways cells divide—mitosis and meiosis. Each of
these methods of cell division has special characteristics. One of the key differences in mitosis
is a single cell divides into two cells that are replicas of each other and have the same number
of chromosomes. This type of cell division is good for basic growth, repair, and maintenance. In
meiosis a cell divides into four cells that have half the number of chromosomes. Reducing the
number of chromosomes by half is important for sexual reproduction and provides for genetic
diversity.
MITOSIS CELL DIVISION
Mitosis is how somatic—or non-reproductive cells—divide. Somatic cells make up most of your
body's tissues and organs, including skin, muscles, lungs, gut, and hair cells. Reproductive cells
(like eggs) are not somatic cells.
In mitosis, the important thing to remember is that the daughter cells each have the same
chromosomes and DNA as the parent cell. The daughter cells from mitosis are called diploid
cells. Diploid cells have two complete sets of chromosomes. Since the daughter cells have
exact copies of their parent cell's DNA, no genetic diversity is created through mitosis in normal
healthy cells.
Mitosis cell division creates two genetically identical daughter diploid cells.
The mitosis cell cycle
Before a cell starts dividing, it is in the "Interphase." It seems that cells must be constantly
dividing (remember there are 2 trillion cell divisions in your body every day), but each cell
actually spends most of its time in the interphase. Interphase is the period when a cell is getting
ready to divide and start the cell cycle. During this time, cells are gathering nutrients and energy.
The parent cell is also making a copy of its DNA to share equally between the two daughter
cells.
The mitosis division process has several steps or phases of the cell cycle—interphase,
prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis—to successfully
make the new diploid cells.
