The DNA of a prokaryotic cell consists of a single chromosome that is in direct contact with the cytoplasm. The nuclear region in the cytoplasm is called the nucleoid. Most prokaryotes are the smallest of all organisms ranging from 0.5 to 2.0 µm in diameter.
https://en.wikipedia.org/wiki/Cell_(biology)
The number of cells in an organ also has bearing on some medical conditions. The authors of the new study find that a healthy liver has 240 billion cells in it, for example, but some studies on cirrhosis have found the disease organ have as few as 172 billion.
http://phenomena.nationalgeographic.com/2013/10/23/how-many-cells-are-in-your-body/
They then came up with estimates for the total number of each kind of cell. They estimate, for example, that we have 50 billion fat cells and 2 billion heart muscle cells. Adding up all their numbers, the scientists came up with…drumroll…37.2 trillion cells. This is not a final number, but it’s a very good start.
http://phenomena.nationalgeographic.com/2013/10/23/how-many-cells-are-in-your-body/
1 Some eukaryotic cells (plant cells and fungal cells) also have a cell wall. 2  Inside the cell is the cytoplasmic region that contains the genome (DNA), ribosomes and various sorts of inclusions. 3  The genetic material is freely found in the cytoplasm.
https://en.wikipedia.org/wiki/Cell_(biology)
Curiosity is justification enough to ponder how many cells the human body contains, but there can also be scientific benefits to pinning down the number too.
http://phenomena.nationalgeographic.com/2013/10/23/how-many-cells-are-in-your-body/
Cells are the smallest unit of life that can replicate independently, and are often called the building blocks of life. The study of cells is called cell biology. Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids.
https://en.wikipedia.org/wiki/Cell_(biology)
There are several types of organelles in a cell. Some (such as the nucleus and golgi apparatus) are typically solitary, while others (such as mitochondria, chloroplasts, peroxisomes and lysosomes) can be numerous (hundreds to thousands).
https://en.wikipedia.org/wiki/Cell_(biology)
Your brain is only about 2% of your body weight, but brain cells use twice as much energy as other cells in your body. Brain cells are always active, even when you sleep. 1  Previous. 2  Continue.
http://www.webmd.com/brain/rm-quiz-amazing-brain
Skin cells, on the other hand, are so sparse that they’d give you a paltry estimate of 35 billion cells. So the author of the new paper set out to estimate the number of cells in the body the hard way, breaking it down by organs and cell types.
http://phenomena.nationalgeographic.com/2013/10/23/how-many-cells-are-in-your-body/
While the number of cells in plants and animals varies from species to species, humans contain more than 10 trillion (10 13) cells. Most plant and animal cells are visible only under the microscope, with dimensions between 1 and 100 micrometres.
https://en.wikipedia.org/wiki/Cell_(biology)
how much cells does a human have
Human have 37.2 trillion cells.