Final answer:
mRNA (messenger RNA) is the type of RNA that is copied from genes and directs the synthesis of proteins. It travels from the nucleus to the cytoplasm to guide protein assembly on ribosomes, with the help of tRNA and rRNA.
Step-by-step explanation:
The RNA molecules that are copied from genes and ultimately direct the synthesis of proteins are called messenger RNA (mRNA). mRNA is synthesized from a DNA template in the nucleus of a cell. It contains the genetic information necessary for the construction of proteins. Once synthesized, mRNA is exported from the nucleus to the cytoplasm, where it interacts with ribosomes, the site of protein synthesis. Transfer RNA (tRNA) carries specific amino acids to the ribosomes to be added to the growing protein chains, while ribosomal RNA (rRNA) is a major component of ribosomes themselves. microRNA (miRNA), on the other hand, plays a role in regulating the use of mRNA for protein synthesis.