Are lipids enzymes? i am very confused on whether or not lipids, proteins, nucleic acids and carbohydrates are enzymes

Lipids are not enzymes, or to put it in another way enzymes are protein in nature and not lipids, nucleic acids or carbohydrates. Enzymes are  defined as organic  substances which speed up biochemical reactions but they remain exactly the way they were before and after the reaction, that is they are not changed, before, during and after the reaction.

Enzymes are a special kind of protein and they exhibit protein characteristics. One of the main characteristics is that they are affected by extreme pH and temperature. When exposed to such, they get denatured. Protein is the only macromolecule that gets denatured and become inactive or damaged permanently

Enzymes work best within a narrow pH and temperature range specific to each enzyme, outside of which  they are rendered inactive.

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.