A diagram of the process of cell division by mitosis.
Click on image for full size
Courtesy of National Center for Biotechnology Information, NIH
How New Cells Are Made: Mitosis
An animal, plant, or other multicellular organism needs to make more cells in order to grow larger. One cell divides into two during growth. Unicellular organisms, like protists, which have only one cell, often reproduce by splitting their one cell into two or more.
When two cells are made out of one during cell division, the genetic material must be duplicated so that there is the same number of chromosomes in the two cells spilt from one. After chromosomes are duplicated, dividing them up is a four-step process called mitosis.
During this step the cell gets ready for mitosis. Duplicated chromosomes are held together. By the end of this step they have changed from thin threads into thick rods. Fibers made of protein begin to form that will eventually help pull the pairs of chromosomes apart.
The membrane that surrounds the cellís nucleus brakes apart and the chromosome duplicates line up at the middle of the cell. The fibers that started to develop during the first phase have become stronger and attach at both ends of the cell as well as to each chromosome.
During this step, the action really happens! Those thick fibers attached to opposite ends of the cell pull the duplicated chromosomes apart into two groups.
A nucleus membrane forms around both groups of chromosomes and rest of the cell begins to divide. With the same genetic material, these two cells are just like the one they were made from!
Shop Windows to the Universe Science Store!
"Ready, Set, SCIENCE!: Putting Research to Work in K-8 Science Classrooms
", from the National Research Council, provides insight on the types of instructional experiences help K-8 students learn science with understanding. Check our other books
in our online store
You might also be interested in:
Kingdom Plantae contains almost 300,000 different species of plants. It is not the largest kingdom, but it is a very important one! In the process known as "photosynthesis", plants use the energy of the...more
Members of the Kingdom Protista are the simplest of the eukaryotes. Protists are an unusual group of organisms that were put together because they don't really seem to belong to any other group. Some protists...more
Do you look a bit like your brothers and sisters? Do you look a bit like your parents? The similarities are because, unless you were adopted, you and the other members of your family have genetic material...more
Jupiter's atmospheric environment is one of strong gravity, high pressure, strong winds, from 225 miles per hour to 1000 miles per hour, and cold temperatures of -270 degrees to +32 degrees (freezing temperature)....more
In July, 1996, it was announced that Dr. David McKay, along with a team of scientists at Johnson Space Center (a division of NASA), had discovered possible fossils of bacteria in a meteorite named ALH84...more
Saturn's atmospheric environment is one of strong gravity, high pressure, strong winds, from 225 miles per hour to 1000 miles per hour, and cold temperatures of -270 degrees to +80 degrees. With winds...more
Titan's atmosphere is a lot like the Earth's, except that it is very cold, from -330 degrees to -290 degrees! Like the Earth, there is a lot of Nitrogen and other complex molecules. There also may be an...more