Final answer:
Cells synthesize proteins via two key processes: transcription, where DNA is transcribed into RNA, and translation, where RNA is translated to form proteins at ribosomes. The sequence of nucleotides in DNA determines the sequence of amino acids in proteins, the assembly of which is facilitated by RNA intermediates.
Step-by-step explanation:
The cell assembles proteins through a process involving DNA and RNA. DNA, present in chromosomes within the nucleus, contains the genetic instructions for protein synthesis. However, proteins are synthesized in the cytoplasm at the ribosomes, so an intermediary RNA molecule is required.
Transcription: From DNA to RNA
Transcription is the process by which the genetic code from DNA is copied into messenger RNA (mRNA). During transcription, an enzyme called RNA polymerase binds to DNA and assembles a strand of mRNA. The mRNA strand is a sequence of nucleotides complementary to the DNA template and carries the genetic information out of the nucleus through pores in the nuclear membrane.
Translation: From RNA to Protein
Once mRNA reaches the ribosome, a process called translation occurs. Here, transfer RNA (tRNA) molecules bring amino acids to the ribosome, where they are added to the growing polypeptide chain in the order specified by the mRNA code. The sequence of amino acids determines the unique three-dimensional structure and function of the protein. This process continues until a stop codon is encountered on the mRNA, signaling the end of protein synthesis.
This sequence of events, DNA to RNA to Protein, is known as the central dogma of molecular biology. Translation and transcription are the key processes that turn the genetic code into functional proteins.