2021/2/21 Topic 2: tRNA At the heart of protein synthesis is the translation of nucleotide sequence information into amIno acids. This work is accomplished by tRNA 16
2021/2/21 16 Topic 2: tRNA At the heart of protein synthesis is the translation of nucleotide sequence information into amino acids. This work is accomplished by tRNA
2021/2/21 2-1: tRNA are adaptors between codons and amino acids 1. The are many types of tRNA molecules in cell(40). n 2. Each tRNa molecule is attached to a m刀 specific amino acids(20)and each recognizes a particular codon, or codons(61), in the mRNA 3. All tRNAs end with the sequence 5 CCA-3 at the 3 end where the aminoacyl tRNA synthetase adds the amino acid
2021/2/21 17 1. The are many types of tRNA molecules in cell (~40). 2. Each tRNA molecule is attached to a specific amino acids (20) and each recognizes a particular codon, or codons (61), in the mRNA 3. All tRNAs end with the sequence 5’- CCA-3’ at the 3’ end, where the aminoacyl tRNA synthetase adds the amino acid. 2-1: tRNA are adaptors between codons and amino acids TRANSFER RNA
2021/2/21 Primary structure 1. tRNAs are 75-95 nt in length 2. There are 15 invariant and 8 semi-invariant residues. The position of invariant and semi-variant nucleosides play a role in either the secondary and tertiary structure 3. There are many modified bases, which sometimes accounting for 20% of the total bases in one tRNa molecule. over 50 different types of them have been observed
2021/2/21 18 1. tRNAs are 75-95 nt in length. 2. There are 15 invariant and 8 semi-invariant residues. The position of invariant and semi-variant nucleosides play a role in either the secondary and tertiary structure. 3. There are many modified bases, which sometimes accounting for 20% of the total bases in one tRNA molecule. Over 50 different types of them have been observed. Primary structure
4.Pseudouridine(yU)is a modified base.2/2/p These modified bases in trna lead to improved tRNA function uridine pseudouridine dihydrouridine ribose N N HHHH ON H ON ON ribose <ribose Fig 14-3 unusual bases 19
2021/2/21 19 Fig 14-3 unusual bases 4. Pseudouridine (U) is a modified base. These modified bases in tRNA lead to improved tRNA function
2-2: tRNAs share a common 2021/2/21 secondary structure that resemble a cloverleaf p- The cloverleaf structure is a U common secondary structural T representation of tRNA w molecules which shows the base 2 paring of various regions to form four stems (arms) and three loops 20
2021/2/21 20 ◼ The cloverleaf structure is a common secondary structural representation of tRNA molecules which shows the base paring of various regions to form four stems (arms) and three loops. 2-2: tRNAs share a common secondary structure that resemble a cloverleaf TRANSFER RNA