What purposes do transcription and translation serve for a cell?

your DNA is just chemicals telling you which proteins to put where. transcription takes the genes from your DNA which speaks in DNA and transcribes it to RNA which is what the ribosomes speak. the ribosomes then take the amino acids from the rough endoplasmic reticulum and uses the RNA to figue out what order to make the amino acid chain. this is called translation. DNA uses thymine, adenine, cytosine and guanine. Transcription takes the thymine and changes it to Ursine which is just a chemical that the ribosome understands. the translation occurs with tests of 3. so if the RNA code says UGA that codes for a specific amino acid (UGA is an important one because it actually codes for nothing signaling for the translation to stop because it had been competed) if AAG is one of them the ribosome will pick up a certain amino acid (idk which one, there is a table that shows what all the 3 combinations (each 3 is a codon) means)from the rough ER and add it to the amino acid chain. i hope that helped.

Transcription converts DNA into RNA
Translation converts RNA into protein

To extend what John said

Transcription converts DNA into RNA
Translation converts RNA into protein
Proteins are vital to form cell membranes and almost all of the structural parts of the cell itself. If the cell is part of a complex organism, enzymes (which are made of protein) will control virtually all of the bodies chemical reactions, and without transcription and translation, the cell and the organism can not continue to exist for very long!