ANSC 221 (Exam 4): Lecture 10- Translation synthesis of proteins

What dictates the synthesis of proteins in an organism?

The DNA inherited by the organism.

What is translation in the context of protein synthesis?

The synthesis of a polypeptide using the information in the mRNA.

What is the role of ribosomes in protein synthesis?

Ribosomes build proteins by joining amino acids in the correct order and are the sites of translation.

What are codons?

Triplets of nucleotides in DNA or mRNA that specify an amino acid.

How many codons are there, and how many code for amino acids?

There are 64 codons; 61 code for amino acids and 3 are stop signals.

What is the significance of the codon AUG?

It codes for the amino acid methionine and functions as a start signal.

What is the structure of transfer RNA (tRNA)?

tRNA consists of a single RNA strand about 80 nucleotides long, shaped like an L, with an anticodon on one end and an amino acid attachment site on the other.

What is the function of the anticodon in tRNA?

The anticodon is a nucleotide triplet that base-pairs with a specific mRNA codon.

What is meant by redundancy in the genetic code?

More than one codon may specify a particular amino acid, but no codon specifies more than one amino acid.

What are the three binding sites of a ribosome?

A site (amino acid), P site (polypeptide chain), and E site (discharge tRNAs).

What initiates the translation process?

The small ribosomal subunit binds to the 5' cap of the mRNA and the initiator tRNA until it reaches the start codon (AUG).

What are the three steps of elongation in translation?

Codon recognition, peptide bond formation, and translocation.

What occurs during the termination of translation?

A stop codon reaches the A site, a release factor is added, and the polypeptide is released.

What modifications occur to polypeptide chains after translation?

Polypeptide chains can undergo protein folding and post-translational modifications.

How do multiple ribosomes affect protein synthesis?

Multiple ribosomes can translate a single mRNA simultaneously, allowing for rapid production of polypeptides.

How does gene expression differ in eukaryotes compared to prokaryotes?

In eukaryotes, the nuclear envelope separates the processes of transcription and translation.

What are the cellular components involved in translation?

Ribosomes, mRNA, and tRNA.

What is the function of the 5' cap and poly-A tail in mRNA?

They protect mRNA from degradation and assist in the initiation of translation.

What is the significance of introns and exons in mRNA?

Introns are cut out, and exons are spliced together to form the final mRNA coding sequence.

What is the process of translating mRNA into proteins called?

Translation

What are the building blocks of proteins?

Amino acids

What structure synthesizes proteins in the cell?

Ribosome

What is the role of mRNA in protein synthesis?

mRNA carries the genetic information from DNA to the ribosome for translation.

What is a codon?

A sequence of three nucleotides in mRNA that specifies an amino acid.

What is the function of tRNA in translation?

tRNA brings the appropriate amino acid to the ribosome based on the codon sequence.

What is the significance of the start codon?

The start codon (AUG) signals the beginning of translation.

What are stop codons and their role in translation?

Stop codons (UAA, UAG, UGA) signal the termination of protein synthesis.

What is meant by the redundancy of the genetic code?

Multiple codons can code for the same amino acid.

What is the direction of translation?

Translation occurs in the 5′ to 3′ direction.

What are the three sites found in a ribosome during translation?

A site (aminoacyl-tRNA binding site), P site (peptidyl-tRNA binding site), and E site (exit site).

What are post-translational modifications?

Chemical modifications made to proteins after translation, which can affect their function and localization.