BioChem 406 - Lecture 20: tRNA

What is the main functional role of tRNA?

It serves as the adaptor between mRNA and amino acids

What are the two most important structural features of tRNA?

The anti-codon arm and the amino acid arm

What is the function of the anti-codon arm?

It holds the anti-codon sequence that base-pairs with the mRNA

What is the function of the amino acid arm?

It uses its 3’ end to attach to the amino acid

What is the large-scale structure of tRNA?

It is a right-handed helix, similar to A-DNA

What is the Wobble position?

The third spot in the anti-codon that can have extended base pairing

What pairs with a C in the wobble position of tRNA?

G

What pairs with an A in the wobble position of tRNA?

U

What pairs with a U in the wobble position of tRNA?

A or G

What pairs with a G in the wobble position of tRNA?

C or U

What pairs with an I in the wobble position of tRNA?

A, U, or C

Inosine is ____

a deaminated adenosine

Since anti-codons are actually very similar in structure, how are tRNAs differentiated?

There are several modified bases throughout the molecule

What enzyme assigns the codons?

tRNA synthetases

How many tRNA synthetases are there?

There are 20, one for each amino acid

Charged tRNA is also known as ____

aminoacylated tRNA

What is step 1 when charging tRNA?

The amino acid is adenylated by tRNA synthetases, which cleaves two phosphates off one ATP. This produces a mixed anhydride

What is step 2 when charging tRNA?

tRNA synthetase uses the adenylated amino acid to turn tRNA into aminoacyl tRNA