Question

1-

The changing or activation of a tRNA molecule includes:

Group of answer choices

the covalent attachment of an amino acid to the 5' terminal adenosine of the tRNA.

the covalent attachment of an amino acid to the 3' terminal cytosine of the tRNA.

the covalent attachment of the carboxyl group of an amino acid to the tRNA.

the covalent attachment of the amino group of an amino acid to the tRNA.

2-

A difference between a Class I and a Class II tRNA synthetase is (select all that apply):

Group of answer choices

the Class I synthetase requires ATP as a cofactor and the Class II does not.

the Class I synthetase reaction requires a transesterification reaction not necessary in the Class II reaction.

the Class II synthetases are typically monomeric, whereas the Class I enzymes frequently function as multimeric protein complexes.

the Class I synthetase uses the 2' OH of the 3' end of the tRNA as a nucleophile and the Class II uses the 3' OH.

3-

What result allowed Dintzis to conclude that proteins are synthesized from the N terminus to C terminus?

Group of answer choices

All peptides produced from the experiment had similar levels of labeled H and C.

The more newly synthesized peptides had greater levels of radiolabeled C.

Reticulocytes only produce a single protein.

The more newly synthesized peptides had greater levels of radiolabeled H.

Answer 1

Qn1.

The changing or activation of a tRNA molecule includes: The covalent attachment of the carboxyl group of an amino acid to the tRNA ​​​​​​.

tRNAs are charged by the attachment of an amino acid to the 3' terminal adenosine nucleotide via acyl linkage.

Qn2.

A difference between a Class I and a Class II tRNA synthetase is

the Class I synthetase uses the 2' OH of the 3' end of the tRNA as a nucleophile and the Class II uses the 3' OH.

the Class I synthetase reaction requires a transesterification reaction not necessary in the Class II reaction.

Aminoacyle-tRNA synthetase enzyme carryout the aminoacylation of tRNA. There are 2 types of aminoacyle-tRNA synthetase enzyme Class I and class II . Class I is monomeric and class II is mainly dimeric. Both of them require ATP.

Qn3.

The more newly synthesized peptides had greater levels of radiolabeled C This result allowed Dintzis to conclude that proteins are synthesized from the N terminus to C terminus.

A radiolabeled amino acid was provided to the reticulocyte preparation . This preparation synthesizing haemoglobin. After synthesis of the completed globin chain it was found that the concentration of radioactive products are more in C-terminas. Which was the last part of the globin chain to be formed. It concludes that proteins are synthesized from the N to C terminus.