Biology, Eighth Edition (Raven)

Chapter 15: Genes and How They Work

Translation Elongation

Why are ribosomes needed for protein synthesis? Ribosomes are the central structures of protein synthesis. They bring all the components needed to build a protein together in a controlled fashion that causes amino acids to link up in a chain. Ribosomes have sites that bind mRNA and tRNA and move them through the ribosome. The movement of RNA through the ribosome adds the amino acids to the chain, one at a time. Without ribosomes, the tRNA and the mRNA would have to spontaneously come together. After the association of the two kinds of RNA, the amino acids attached to the tRNA would have to link to together. Without a ribosome this would take a very long time. Ribosomes are the organizers of protein synthesis.

View the animation below, then complete the quiz to test your knowledge of the concept.


During translation elongation, amino acids are brought to the ribosome with the help of

Which of the following occurs as a result of translocation?
A)the tRNA that was in the A site moves into the E site
B)the tRNA that was in the P site moves into the A site
C)the tRNA that was in the E site moves into the P site
D)the tRNA that was in the E site moves into the A site
E)the tRNA that was in the P site moves into the E site

Which of the following statements about peptidyl transferase is TRUE?
A)It catalyzes the formation of peptide bonds.
B)It is present in the 50S ribosomal subunits.
C)It is a protein.
D)A and B
E)A, B and C

Translocation is promoted by the elongation factor EF-G.

An uncharged tRNA is one that is not carrying an amino acid.
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