As you’ve probably guessed, the colors in a drawing of a cell are just to tell different parts of the cell apart. In general, human cells are transparent, which means light passes right through them. Some exceptions are red blood cells which are red because of iron content and pigmented cells like in a freckle. A big part of science is seeing things that you can’t see normally with your eyes. The most well-known way to do this is using a microscope which makes really tiny things look huge. To see cells, a common technique is to use a dye that will stain certain parts of a cell so that you can see them. But in reality, most cells don’t have any real color.

Another part to this question is what color is to begin with. Humans perceive color when certain types of light hit an object and are reflected into their eyes. A rainbow for instance shows all of the different colors we can see. However, for some animals with good night vision such as owls, their idea of color is different. Their eyes can process light that our eyes aren’t adjusted for. So in a sense, no object really has a color. Humans perceive an object to be a certain color which is a property of the human as well as the object.

It varies from cell to cell. For plants, we see that they are green. Really, the cells themselves are clear but the chlorophyll inside the chloroplast is green, so we really just see the color of the chloroplast. Similarly for blood, a red blood cell is clear, but has red hemoglobin inside it that makes certain parts look red. We only see at high levels so it looks red to us. Most cells are like this.

Most cells are basically clear. Cells with pigments (like those in your skin and hair) have color due to the pigments (melanin in this case, which is brown). Chloroplasts in plant cells are green (they are the reason why plants are green).

Cells are typically colorless and basically transparent, although certain types of cells that contain pigments would exhibit the colors of their pigments. For instance, many plant cells from leaves have the pigment chlorophyll, which looks green. Many flowers, on the other hand, have a variety of pigments which are generally called carotenoids and can range in color from yellow to orange to red. Another example is human hair, which has varying amounts of a pigment called melanin and results in a variety of colors from light yellow to very dark brown.