Protein synthesis

Definition

Protein synthesis is the biological process in which cells generate new proteins based on the genetic instructions encoded in DNA. This process involves the transcription of DNA into messenger RNA (mRNA), followed by translation where ribosomes read the mRNA sequence to assemble amino acids into a polypeptide chain, ultimately folding into functional proteins. It is a crucial mechanism that links genes to their corresponding traits and functions within organisms.

5 Must Know Facts For Your Next Test

1. Protein synthesis occurs in two main stages: transcription and translation, with each step involving distinct molecular players like RNA polymerase and ribosomes.
2. During transcription, the DNA sequence of a gene is transcribed into mRNA, which serves as a template for protein synthesis.
3. The genetic code is composed of codons, sequences of three nucleotides in mRNA that correspond to specific amino acids or stop signals during translation.
4. Ribosomes can be free-floating in the cytoplasm or attached to the endoplasmic reticulum, impacting the destination and function of the synthesized proteins.
5. Mutations in DNA can lead to changes in mRNA and subsequently affect the amino acid sequence of proteins, potentially altering their structure and function.

Review Questions

• How do transcription and translation work together in protein synthesis?
  • Transcription and translation are sequential processes that form the basis of protein synthesis. During transcription, an RNA polymerase enzyme synthesizes mRNA from a DNA template, effectively creating a copy of the gene's instructions. This mRNA then exits the nucleus and enters the cytoplasm where translation occurs. Ribosomes read the mRNA sequence and translate it into a specific sequence of amino acids, forming a polypeptide chain that will fold into a functional protein.
• Discuss how mutations can impact protein synthesis and what consequences this may have for an organism.
  • Mutations can alter the DNA sequence of a gene, leading to changes in the corresponding mRNA during transcription. Depending on the nature of the mutation—whether it is a point mutation, deletion, or insertion—the resulting changes can affect the amino acid sequence produced during translation. This may lead to nonfunctional proteins or proteins with altered functions, potentially causing diseases or developmental issues in an organism due to disrupted cellular processes.
• Evaluate the role of ribosomes in protein synthesis and how their structure contributes to their function.
  • Ribosomes play a critical role in protein synthesis as they are the sites where translation occurs. Their structure consists of ribosomal RNA (rRNA) and proteins, forming two subunits that come together during translation. The large subunit facilitates peptide bond formation between amino acids, while the small subunit ensures accurate reading of mRNA codons. This complex structure allows ribosomes to efficiently link amino acids according to the genetic code, making them essential for producing diverse proteins necessary for life.

Related terms

transcription: The process of copying a segment of DNA into messenger RNA (mRNA), which carries the genetic information from the nucleus to the cytoplasm.

translation:

The stage of protein synthesis where ribosomes read mRNA sequences to synthesize proteins by linking amino acids together in the order specified by the mRNA.

ribosome:

A molecular machine within cells that facilitates the translation of mRNA into protein, composed of ribosomal RNA (rRNA) and proteins.