Draw a diagram of a hypothetical eukaryotic polysome in...

Draw a diagram of a hypothetical eukaryotic polysome in which nascent protein chains are visible. Identify the 5 '- and $3^{\prime}$ 'ends of the mRNA and use an arrow to indicate the direction the ribosomes are moving along the mRNA. Use $\mathrm{N}$ and $C$ to indicate the amino and carboxyl ends of one of the growing polypeptides.

Key Concepts

Eukaryotic Polysome

A eukaryotic polysome consists of multiple ribosomes attached to a single mRNA molecule, simultaneously engaged in translation. This organization allows for efficient protein synthesis, as several ribosomes can translate different regions of the same mRNA concurrently, speeding up the production of a polypeptide.

mRNA Structure and Directionality

Messenger RNA (mRNA) exhibits polarity with distinct 5' and 3' ends. In eukaryotic cells, the translation process initiates at the 5' end and proceeds toward the 3' end. The diagram should clearly mark these ends, illustrating that ribosomes bind at the 5' end and move in the 5'-to-3' direction in order to read the codons sequentially.

Ribosome Movement and Translation Process

Ribosomes function as the molecular machines that synthesize proteins by moving along the mRNA strand. As they progress in the 5'-to-3' direction, they interpret the codon sequence, facilitating the addition of amino acids into a growing polypeptide chain. An arrow marking this direction in the diagram is essential to visually communicate this process.

Nascent Polypeptide Chain Orientation

During translation, a nascent (growing) polypeptide chain emerges from the ribosome. The polypeptide is synthesized with a free amino (N) terminus at the beginning and a carboxyl (C) terminus at the end. Labeling the N and C termini on one of the chains in the diagram is key to understanding the orientation and direction of protein synthesis.

Transcript

00:01 Okay, so here we are looking at what happens during translation.

00:06 So we have some mri here and some codons, amorphous blob surrounding the codons.

00:57 Okay, this is my attempt at replicating the photo.

01:01 But hopefully you are looking at the book where everything is much clearer.

01:06 So we are to label some things.

01:09 And a wants us to label which ends or which of the m rna.

01:14 So translation occurs from the 5 prime end to the 3 prime end, so that'll put 5 on the left and 3 on the right.

01:28 Okay, so that's part a.

01:30 Part b wants us to look at the ap and e sites.

01:34 So within ribosome, such as above, we're going to have the e site, followed by the p site, followed by the a site.

01:55 So e is exit site, which makes sense because if you're headed in this direction, and that's the last place it gets, right? so we'll go from a to p to e.

02:04 The p is the peptle -t rna binding site, and the a is the aminoactyl t -rna -binding site, and the a is the aminoactyl t -rna -b.

02:18 Binding sites.

02:19 We have two binding sites followed by the exit site.

02:24 So in this particular diagram i would say the the a site is going to be kind of hereish.

02:40 The p site's going to be hereish and the e site would be here.

02:47 Okay so now i have the start codon and the start codon says part c happens to be a ug and the stop codon is uag.

03:02 And so that's part d here is the stop codon...