PROTEIN SYNTHESIS PART 2 TRANSLATION 1 Translation Translation

PROTEIN SYNTHESIS PART 2 TRANSLATION 1

Translation § Translation is the process of decoding the m. RNA into a protein. § Ribosomes read m. RNA three bases or 1 codon at a time and construct the proteins § This process could not occur without another type of RNA called t. RNA (transfer RNA) 2

Transfer RNA (t. RNA) § Has a clover-leaf shape § Picks up the appropriate amino acid floating in the amino acid methionine attachment site cytoplasm § Transports amino acids to the m. RNA § Recognizes the appropriate codons on the m. RNA and bonds to them. § Have anticodons that are complementary to U A C m. RNA codons anticodon 3

Codons and Anticodons § Each 3 -letter codon in the m. RNA has an anticodon on the t. RNA that will match it. § Below shows a series of codons. Fill in what the anticodons would look like below. AUG|CGU|ACU|GAU|CGU|UCA|GAU|UGA UAC GCA UGA CUA GCA AGU CUA ACU

Ribosomes § Made of a large and small subunit § Composed of globular-shaped r. RNA (40%) and proteins (60%) § Have two sites for t. RNA attachment -- P and A Large subunit P Site Small subunit A U G A Site m. RNA C U U C G 5

Step 1 Initiation § m. RNA transcript start codon AUG attaches to the small ribosomal subunit § Small subunit attaches to large ribosomal subunit Large subunit P Site Small subunit A Site m. RNA A U m. RNA G C transcript U A C U U C G 6

Step 1 Initiation 7

Step 2 Elongation § As ribosome moves, two t. RNA with their amino acids move into site A and P of the ribosome § Peptide bonds join the amino acids 8

Step 2 Elongation 9

m. RNA Codons Join the Ribosome Large subunit P Site A Site m. RNA A U G Small subunit C U A C U U C G 10

Initiation aa 1 1 -t. RNA anticodon hydrogen bonds U A C A U G codon aa 2 2 -t. RNA G A U C U A C U U C G A m. RNA 11

Elongation peptide bond aa 1 aa 3 aa 2 3 -t. RNA 1 -t. RNA anticodon hydrogen bonds U A C A U G codon 2 -t. RNA G A U C U A C U U C G A m. RNA 12

aa 1 peptide bond aa 3 aa 2 1 -t. RNA 3 -t. RNA U A C (leaves) 2 -t. RNA A U G G A A G A U C U A C U U C G A m. RNA Ribosomes move over one codon 13

aa 1 peptide bonds aa 2 aa 4 aa 3 4 -t. RNA 2 -t. RNA A U G 3 -t. RNA G C U G A A C U U C G A A C U m. RNA 14

aa 1 peptide bonds aa 4 aa 2 aa 3 2 -t. RNA 4 -t. RNA G A U (leaves) 3 -t. RNA A U G G C U G A A C U U C G A A C U m. RNA Ribosomes move over one codon 15

aa 1 peptide bonds aa 5 aa 2 aa 3 aa 4 5 -t. RNA U G A 3 -t. RNA 4 -t. RNA G A A G C U A C U U C G A A C U m. RNA 16

peptide bonds aa 1 aa 5 aa 2 aa 3 aa 4 5 -t. RNA U G A 3 -t. RNA G A A 4 -t. RNA G C U A C U U C G A A C U m. RNA Ribosomes move over one codon 17

aa 4 aa 5 Termination aa 199 aa 3 primary structure aa 2 of a protein aa 200 aa 1 200 -t. RNA A C U terminator or stop codon C A U G U U U A G m. RNA 18

Termination 19

End Product –The Protein! • The end products of protein synthesis is a protein - A sequence of amino acids bonded together by peptide bonds aa 2 aa 1 aa 3 aa 4 aa 5 aa 199 aa 200 20

Messenger RNA (m. RNA) start codon m. RNA A U G G G C U C C A U C G G C A U A A codon 1 protein methionine codon 2 codon 3 glycine serine codon 4 isoleucine codon 5 codon 6 glycine alanine codon 7 stop codon Protein aa 1 aa 2 aa 3 peptide bonds aa 4 aa 5 aa 6 21