The image above was lifted from an article in "The Daily Mail," found here.
It is a really bad representative cell, since it is a famous cancer cell line known as HeLa cells and it behaves in ways very much unlike good, normal cells. But, you can see a nucleus (stained for DNA in blue) and some fibers that are part of the "cytoskeleton." To see those, the researchers have used a technique to make them glow either red (microtubules) or green (actin fibers…or microfilaments.

As I said earlier, a common theme in biology is how large "macromolecules" from subunits, usually known as monomers.
Proteins are arguably the most important and, inarguably, the most diverse of all the macromolecules.
Each protein begins as a long strand of hundreds (or thousands) of amino acids. Since there are 20 different amino acids commonly used, 100 amino acids would have 20¹⁰⁰ possible sequences.
In practice, you won't see all possible ones and they are not randomly put together. Instead, the information in the DNA is used to specify what sequence is made (through a process we will learn about).
These chains then fold into complex structures you have seen.

In the same way that one can trace your heritage using your DNA, the evolutionary history of all living things can be fit to a tree of life. You might be surprised where you fall.