Protein Synthesis

 What is Protein Synthesis

Protein synthesis is essential because proteins are the building blocks of life. They perform nearly all functions in a cell, including:

- Building and Repairing Tissues – Proteins make up muscles, skin, and organs.

- Enzymes – Proteins act as biological catalysts, speeding up chemical reactions.

- Hormones – Some proteins (like insulin) regulate body functions.

- Transport – Proteins like hemoglobin carry oxygen in the blood.

- Defense – Antibodies help fight infections.


Since DNA holds the instructions for making proteins, cells need a process to read these instructions and build the correct proteins. That process is protein synthesis.


Before we start protein synthesis we must know what are codons:

- Codons - 3 letter mRNA sequence which codes for an Amino Acid 

- AntiCodon - tRNA sequence complementary to mRNA’s codons, attaches to the mRNA


Protein synthesis happens in two main stages:


--> Transcription (in the nucleus)


--> Translation (in the cytoplasm)


Transcription: 

  • DNA serves as a template to create messenger RNA (mRNA)
  • The enzyme RNA polymerase unzips the DNA and builds a complementary RNA strand
  • The RNA strand uses Uracil (U) instead of Thymine (T).
  • Once mRNA is made, it leaves the nucleus and moves to a ribosome in the cytoplasm.


    • Translation: 

  • The ribosome reads the mRNA three bases at a time (these three bases form a codon)
  • Transfer RNA (tRNA) brings the correct amino acids to match the codons.
  • Each tRNA has an anticodon that pairs with the mRNA codon.
  • The ribosome links the amino acids together to form a protein (polypeptide chain).
  • The process continues until a STOP codon is reached.

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