Do All the Cells in a Human Body Start as one Cell?
All the cells in a human body start as one cell, a fertilized egg containing 1/2 the mothers DNA and 1/2 the fathers. That cell divides many times creating a unique person. The process is called cell division or more specifically cytokinesis.
The Evolution of You
You started life as one cell, but today you are the proud owner of about 37 trillion rotating cells, comprising 200 different types of cells, each with the same DNA (with a few exceptions) which provides “the blueprint” to make you.
Most new cells have a chance of expressing genes that will make it function as one of each of the 200 different types of cells. Exceptions include:
- Mature red blood cells which contain no DNA
- The sperm and the egg that have half the amount of DNA
- B cells in which some of the DNA has been rearranged to make antibodies.
A video showing how a sperm and egg join to become a fertilized egg cell.
What is the Single Cell that All Cells Come From?
The original cell is a fertilized egg cell (your biological mother’s egg fertilized by your biological father).
The sperm has half the DNA; the egg has half. When the sperm and egg come together, they create one whole.
NOTE: Interestingly, we think the first complex cells (of which a fertilized egg cell is one) evolved from a similar joining of unique organisms. In short, in a very similar manner to the way a sperm and egg made you.
How Do Cells Go From One to 37 Trillion?
Cells reproduce by division; when they divide they make a copy of themselves, and each copy contains the same DNA. When a parent cell has “daughter cells” there is a chance that the new cell will have a different set of genes expressed than the parent. The set of genes that are expressed determines what sort of cell the cell will be, and what sort of proteins it will make. Cells and Proteins are the primary building blocks that create your body and make it function.
Genetics 101 (Part 1 of 5): What are genes?.