Translation Flashcards

Flashcards about Translation

What is Translation?

The conversion of the sequence of nucleotides of the messenger RNA (mRNA) transcript of a (DNA) gene, into a sequence of amino acids that will make a functional protein.

What is a codon?

A combination of three nucleotides on the mRNA. It represents a single amino acid.

What is the function of transfer RNA (tRNA) molecules in translation?

They bring the amino acids into the translation process and bind to the codons on the mRNA.

What are the three main steps in translation?

Initiation, elongation, and termination.

What are two key features of the genetic code?

The genetic code is non-overlapping and continuous.

What serves as the start codon and what does it encode?

AUG, encoding methionine.

What does it mean that the genetic code is degenerate?

The genetic code is degenerate, meaning that many amino acids can be coded by many different codons.

What are the three stop codons?

UAA, UAG, and UGA.

In what direction is mRNA typically translated?

mRNA is typically translated from its 5’ end towards its 3’ end.

What is the role of specific nucleotide sequences found between the 5’ end and the first AUG codon of mRNA?

Recognition points for the rRNA molecule, helping guide the entire complex to the first AUG codon from the 5’ end.

What is the function of aminoacyl-tRNA synthetases?

They link a single amino acid to a single type of tRNA molecule.

How are amino acids attached to their tRNA?

Through an ester bond linking the carboxylic acid function of the amino acid to the free alcohol on the ribose of the nucleotide at the 3’ end of the tRNA molecule.

What is the third position in the tRNA molecule often referred to as?

The Wobble position.

What are the two main subunits of the ribosomal complex?

The multi-protein ribosomal complex is composed of two large subunits: the 30S and 50S complex.

What are the three pockets of space in the ribosomal complex to hold tRNA molecules?

E, P, and A.

What modified amino acid is carried by the tRNA molecule that binds to the 'P' site during initiation?

N-formyl-methionine.

What does the transpeptidation reaction involve?

The transpeptidation reaction involves a nucleophilic substitution of the amino group of one amino acid on the ester linkage between the second amino acid and its tRNA.

After the initiation factors (IFs) are released, what set of proteins will replace them?

Elongation factors (EFs).

What happens during translocation?

The ribosomal complex moves over the mRNA to the next codon.

When the ribosomal complex reaches a 'STOP' codon at its 'A' site, what is replaced the elongation factors (EFs)?

Release factors (RFs).

What is a polyribosome?

Multiple ribosomal complexes can attach to a single strand of mRNA at the same time.

What are some examples of post-translational modifications?

Folding, proteolytic cleavage, chemical modification, glycosylation, modification with lipids, phosphorylation, acetylation, methylation, and transport to specific cellular locations.

How do mutations before the start codon or after the stop codon, affect the protein functionality?

Mutations in the DNA before the START or after the STOP codon will not affect the functionality of the protein.

How does the degeneracy of the genetic code protect the translation process from mutations in DNA?

Many different codons encode for the same amino acid.