Chapter 10.4: RNA Is Translated into Amino Acids by Ribosomes

Flashcards from Chapter 10.4 of Principles of Life, 3rd Edition.

Transfer RNAs (tRNAs)

RNA molecules that link the information in an mRNA codon with a specific amino acid, reading and delivering the appropriate codon to the ribosome for bond catalysis

• To perform this, they covalently bond to amino acids at their 3’ end and bind to with mRNA with a semi-complimentary anticodon while not binding with the ribosome

5’ to 3’

The direction in which tRNA anticodons translate, reading mRNA in the 3’ to 5’ direction

Wobble

This is exhibited on the 3’ end of the tRNA codon to pair with more than one partner, making anticodons not strictly complimentary

• Seen with the base hypoxanthine, which does this with A, C, and U to enable wider recognition

tRNA synthetases

Enzymes that catalyze bond formations between tRNA and amino acid molecule, utilizing ATP to form a high-energy bond that is later broken in the ribosome for polypeptide formation

Ribosomes

The site of mRNA translation with tRNA molecules, composed of two subunits that only come together during translation

• These perform translation by moving across the mRNA towards the 3’ end

• Contain the amino (A), polypeptide (P), and exit (E) sites for binding, with tRNA anticodons binding at the A site, linking the amino acid in the P site, and exiting at the E site for charge

  • Hydrogen bonds validate the created links with codons, ejecting defective links

Initiation complex

The combination of a charged tRNA, small ribosomal subunit, and mRNA

• In prokaryotes, the ribosome directly binds to the start codon

• In eukaryotes, the ribosome binds to the 5’ and moves down until reaching the start codon

This ends with the addition of methionine and the binding of the large subunit, covering the tRNA with the P site to align the second codon with the A site

Initiation factors

Proteins that aid the assembly of the initiation complex

Ribozyme

A ribonucleic acid that acts as an enzyme; rRNA in the ribosome qualifies as one of these as it catalyzes bond breakage between the tRNA and amino acid while forming a peptide bond three bases at a time

Protein release factor

This binds to a stop codon on mRNA, hydrolyzing the bond between the polypeptide chain and tRNA in the P site with the subunits subsequently separating

Polyribosome

An assembly of a strand of mRNA with multiple ribosomes producing polypeptides at the same time