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As humans, we are aware that we are committed to a certain fate: we are born, we live, and we inevitably die. We are less aware that each of the trillion cells in our bodies also have a fate of their own, and everyday each cell has to decide whether to give birth, live, or die.

Not all cells can give “birth” (aka, divide via mitosis to produce two daughter cells: to read more about mitosis, see Leah Bury’s mitosis artwork here). And, even amongst cells that do “give birth”, not all have the same ability to produce daughter cells that can develop into any type of cell. Stem cells are undifferentiated cells with two special abilities: they are able to renew themselves through mitosis and, most importantly, they can develop into any other cell type. One stem cell, depending on what parts of its DNA are read, can turn into a muscle, gut, bone, or skin cell. As such, stem cells are often described as “totipotent,” that is, having the complete (“toti”) potential to become any cell type they want to be.

The processes of stem cell specialization and acquisition of a specific function are together known as “differentiation.” Differentiation dramatically changes a stem cell’s characteristics, modifying its shape, metabolic activity, and function. These changes are driven by alterations at the DNA transcription level (to read more about that, go to Leah Bury’s post on the central dogma here).

Like humans, cells divide, differentiate, live and, eventually, they undergo cell death. But cell death is not all doom and gloom; it’s actually essential for our survival as an organism. Cell death allows our body to clear out unhealthy cells, such as cells that are cancerous or infected with harmful viruses.

There are many types of cell death, but the most common one is “apoptosis.” Apoptosis is also known as “programmed cell death,” which highlights its positive role in the long-term survival of an organism. A sick cell will not linger once it’s past the point of no return. It follows a set of instructions, becomes “apoptotic,” and dies, clearing the way for healthy cells that will also divide, live and die.

The word apoptosis comes from the Greek word for the “falling off” of leaves from a tree. But, unlike leaves that tend to linger on the ground, the debris of dead cells are quickly vacuumed away by macrophages, a cell that hangs around sites of cell death or infection and hungrily eats up anything that may cause our bodies harm.

Contributed by Leah Bury, a postdoc at the Whitehead Institute in Cambridge, and our Featured Artist for June, 2018. To meet Leah and see more of her art, click here.

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