120 likes | 255 Views
Chapter 8. Section 8.5: Translation. Objectives . SWBAT describe how mRNA codons are translated into amino acids. SWBAT summarize the process of protein synthesis. Vocabulary. Translation Codon Stop codon Start codon Anticodon . The Process of Translation.
E N D
Chapter 8 Section 8.5: Translation
Objectives • SWBAT describe how mRNA codons are translated into amino acids. • SWBAT summarize the process of protein synthesis.
Vocabulary • Translation • Codon • Stop codon • Start codon • Anticodon
The Process of Translation • Translation is the process that converts, or translates, an mRNA message into a polypeptide. • One or more polypeptide chains make up a protein. • While DNA and RNA only use four nucleotides each in their codes, the language of proteins uses 20 amino acids.
Triplet Code • A codon is a three-nucleotide RNA sequence that codes for an amino acid. • The genetic code matches each codon to its amino acid or function (the start/stop codons).
Triplet Code Methionine is the start codon while there are three stop codons.
Triplet Code – for Amino Acids • A change in the order in which codons are read changes the resulting protein. • Regardless of the organism, codons code for the same amino acid.
Anticodon • An anticodon is a set of three nucleotides that is complementary to an mRNA codon (a codon of CCC binds with an anticodon of GGG). • An anticodon is carried by a tRNA.
Ribosomes (rRNA) • The large and small ribosomal subunits pull mRNA through the ribosome, reading it one codon at a time. • The large subunit has three binding sites for tRNA’s anticodon.
Translation • For translation to begin, tRNA binds to a start codon and signals the ribosome to assemble. • A complementary tRNA molecule binds to the exposed codon, bringing its amino acid close to the first amino acid.
Translation • The ribosome helps form a polypeptide bond between the amino acids. • The ribosome pulls the mRNA strand the length of one codon.
Translation • The now empty tRNA molecule exits the ribosome. • A complementary tRNA molecule binds to the next exposed codon. • Once the stop codon is reached, the ribosome releases the protein and disassembles.