Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

What cellular pathway is responsible for producing microtubule proteins?

1. DNA → mRNA → protein

2. DNA → RNA → ribosome

3. DNA → mRNA → polypeptide → protein

4. RNA → polypeptide → DNA

The correct answer is: DNA → mRNA → polypeptide → protein

The process of producing microtubule proteins involves several steps that correspond to the central dogma of molecular biology, where genetic information flows from DNA to RNA and eventually to protein. The correct pathway, which is represented in the answer, outlines the essential stages of transcription and translation. Initially, DNA is transcribed into messenger RNA (mRNA), which carries the genetic instructions from the nucleus to the ribosomes, the cellular machinery where proteins are synthesized. This step is crucial as it converts the stable genetic information stored in DNA into a format that can be read and translated. Next, the mRNA undergoes translation, resulting in the formation of a polypeptide chain. Polypeptides are short chains of amino acids, and they will fold and undergo further modifications to become functional proteins, including those that form microtubules. Microtubules are part of the cytoskeleton and play vital roles in maintaining cell shape, enabling cell division, and facilitating intracellular transport. Therefore, the entire pathway from DNA to mRNA, followed by the production of a polypeptide and ultimately a functional protein, is fundamental in the synthesis of microtubule proteins. The other pathways described don't accurately represent the process. For instance, the option that