Translation

Question 1

What is translation?

Answer 1

Creating an amino acid sequence using an mRNA sequence.

Question 2

What are the 2 ribosomal subunit?

Answer 2

Small and large ribosomal subunit.

Question 3

Explain what happens in the initiation of translation.

Answer 3

• mRNA created from transcription lands in the ribosome.
• tRNA goes and lands on the start codon, AUG, carrying the first amino acid.
• The large ribosomal subunit attaches to the small subunit after tRNA lands on the start codon, this initiates the process of translation.
  
  • This process happens through GTP, which provides energy for it to take place.
    *

Question 4

What are the three sites involved in translation? And their roles?

Answer 4

1. The ‘A’ Site: The attachment point of the tRNA to the mRNA.
2. The ‘P’ Site: The location where the tRNA holding the polypeptide chain is found.
3. The ‘E’ Site: This is where the tRNA moves to, to exit the ribosome.

Question 5

Explain what happens in the elongation of translation.

Answer 5

• A tRNA molecule attaches to the A site holding an amino acid.
• The amino acid is joined to the existing polypeptide chain by a peptide bond.
• The ribosome moves the tRNA holding the amino acid chain from the A site to the P site.
• This shifts the empty tRNA to the E site, getting ready to exit the ribosome and be recycled.

Question 6

Explain what happens in the termination in translation.

Answer 6

• When a termination codon is reached, a release factor binds to the A site.
• This causes the disassembly of all components of translation, which can be reused in another process of translation.

Question 7

What is an anticodon?

Answer 7

A sequence found on the tRNA which is complementary to the mRNA codon.

Question 8

What type of bond attaches the amino acid to the tRNA molecule?

Answer 8

Ester bond

Question 9

What enzyme is needed to attach amino acids to tRNA?

Answer 9

Aminoacyl-tRNA synthase

Question 10

Explain how aminoacyl-tRNA synthase attaches amino acids to tRNA.

Answer 10

• A specific amino acid and ATP bind to their corresponding active site.
• ATP loses 2 phosphates to provide energy, become AMP.
• Specific tRNA binds to its active site.
• AMP leaves the enzyme.
• Amino acid attaches to the tRNA
• The tRNA exits the enzyme in the form of charged tRNA.

Question 11

What is the function of polysomes?

Answer 11

Allos. the production of proteins at a faster rate. This happens as multiple ribosomes attach to the same mRNA.

Question 12

What is the primary structure?

Answer 12

A sequence of amino acids.

Question 13

What is the secondary structure?

Answer 13

When the polypeptide chain coils on each other, creating alpha helix and beta sheats.

Question 14

What is the tertiary structure?

Answer 14

When the polypeptide keeps folding, resulting in the formation of ionic, covalent and hydrogen bonds.

Question 15

What are the bonds present in a tertiary structure?

Answer 15

1. Ionic bonds
2. Disulfide (covalent) bonds
3. Hydrogen bonds

Question 16

What is the quaternary structure?

Answer 16

When a protein is made up of more than one polypeptide.