Which cell part, found in virtually all cells, are red blood cells missing?

Red blood cells, also known as erythrocytes, are unique in that they lack a key cellular component found in virtually all other cells: the nucleus. The nucleus is the cell part that contains most of the cell's genetic material, organized as DNA molecules along with a variety of proteins to form chromosomes.

Here are the steps to answer your question:

1. Identify the cell part that is found in virtually all cells. This is the nucleus, which contains the cell's genetic material.

2. Determine if red blood cells contain this cell part. Red blood cells do not contain a nucleus.

3. Therefore, the cell part that red blood cells are missing is the nucleus.