Translation

• What are the processes of translation?

  Initiation, elongation and termination
• What happens before initiation in translation?

  -mRNA is fed into the ribosome

  -the ribosome has binding sites for tRNA

  -tRNA carries amino acids to the ribosome so that they can be joined together to make a polypeptide

  -each tRNA molecule has an anticodon, containing 3 nitrogenous bases
• Describe the process of initiation in translation.?

  -ribosome attaches to start codon

  -complementary tRNA anticodon will bind to mRNA codon

  -a second anticodon will bind at the second codon

  -hydrogen bonds bind the codon and the anticodon
• What is a codon?

  A sequence of 3 bases in the mRNA molecule found in the ribosome that codes for a certain tRNA molecule and therefore a certain amino acid.
• What is an anticodon?

  A sequence of three bases on a tRNA molecule that is complementary to a codon on mRNA.
• Describe the process of elongation in translation.?

  -ribosomal enzymes bind the neighbouring amino acids by forming peptide bonds

  -the first tRNA leaves the ribosome

  -it will collect another amino acid and ATP is required to attach the amino acid to the tRNA

  -the ribosome moves one codon along

  -peptide bonds form between amino acids on adjacent tRNA molecules
• Describe the process of termination in translation.?

  -when a stop codon is reached, the ribosome, mRNA and polypeptide separate from each other

  -the polypeptide can then fold into a protein
• Briefly outline the process of translation.?

  -an mRNA molecule attaches onto a ribosome

  -tRNA molecules attach to specific amino acids and carry them to the mRNA molecule in the ribosome

  -the anticodon on the tRNA binds to the complementary codon on the mRNA, forming a codon-anticodon complex

  -peptide bonds are formed between adjacent amino acids by a condensation reaction
• What is the short definition of initiation in translation?

  A ribosome attaches to a start codon at one end of the mRNA molecule
• What is the short definition of elongation in translation?

  A peptide bond forms between two adjacent amino acids through a condensation reaction
• What is the short definition of termination in translation?

  Amino acids are added until the ribosome reaches a stop codon. The ribosome detaches from the mRNA molecule and the polypeptide is released.
• What post-translational modifications can be made to polypeptides after translation has occurred?

  Carbohydrates are added to make glycoproteins

  Lipids are added to make lipoproteins

  Phosphates are added to make phospho-proteins

  Polypeptides are combined to to form quaternary structure proteins
• What does it mean by 'the DNA code is degenerate'?

  More than one triplet can code for a specific amino acid