cytoplasmic translation

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the formation of a protein in the cytoplasm. This is a ribosome-mediated process in which the information in messenger RNA (mRNA) is used to specify the sequence of amino acids in the protein. [GOC:hjd]

Cytoplasmic translation is the process by which messenger RNA (mRNA) is decoded to synthesize proteins. It occurs in the cytoplasm of eukaryotic cells and is a fundamental process for all living organisms. The ribosome, a complex molecular machine composed of ribosomal RNA (rRNA) and proteins, plays a central role in translation.

The process begins with the binding of mRNA to the ribosome. The mRNA carries the genetic code in the form of codons, three-nucleotide sequences that specify each amino acid. The ribosome then recruits transfer RNA (tRNA) molecules, each carrying a specific amino acid that corresponds to a particular codon.

Translation occurs in three main stages:

1. **Initiation:** This stage involves the assembly of the ribosome on the mRNA, the binding of the initiator tRNA carrying methionine (Met) to the start codon (AUG), and the recruitment of other initiation factors.

2. **Elongation:** During elongation, the ribosome moves along the mRNA, reading codons and adding amino acids to the growing polypeptide chain. Each codon is recognized by a specific tRNA molecule, which delivers its amino acid to the ribosome. The amino acid is then added to the polypeptide chain through the formation of a peptide bond.

3. **Termination:** This stage occurs when the ribosome reaches a stop codon (UAA, UAG, or UGA) on the mRNA. This signals the end of translation, and the polypeptide chain is released from the ribosome.

**Key players in cytoplasmic translation:**

- **Ribosomes:** Composed of rRNA and proteins, they provide a scaffold for mRNA binding and facilitate the recruitment of tRNAs.
- **Messenger RNA (mRNA):** Carries the genetic code from the nucleus to the cytoplasm.
- **Transfer RNA (tRNA):** Delivers amino acids to the ribosome based on the codons in mRNA.
- **Aminoacyl-tRNA synthetases:** Enzymes that attach specific amino acids to their corresponding tRNA molecules.
- **Initiation, elongation, and termination factors:** Proteins that regulate the different stages of translation.

**Regulation of cytoplasmic translation:**

Translation is a highly regulated process that can be influenced by various factors, including:

- **mRNA stability:** The lifespan of mRNA molecules can affect the amount of protein synthesized.
- **Initiation factors:** The availability and activity of initiation factors can regulate the rate of translation initiation.
- **MicroRNAs (miRNAs):** Small non-coding RNA molecules that can bind to mRNA and inhibit translation.
- **Cellular stress:** Stress conditions can trigger changes in translation to ensure cell survival.

**Consequences of translation errors:**

Errors in translation can lead to the production of non-functional or even harmful proteins. These errors can arise from:

- **Mistakes in codon recognition:** tRNA molecules may misinterpret codons, leading to the incorporation of incorrect amino acids.
- **Ribosomal frameshifting:** The ribosome may slip out of its normal reading frame, resulting in the synthesis of a different protein sequence.

**Overall, cytoplasmic translation is a complex and essential process that ensures the accurate and efficient production of proteins. It plays a crucial role in virtually all cellular processes, from growth and development to metabolism and response to environmental changes.'
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Proteins (131)

Compounds (23)