Skip to main content
37 votes
Accepted

Do all proteins start with methionine?

You are correct in thinking that since the translation of mRNA begins with AUG, which codes for methionine, then all proteins should contain a methionine at their N-terminus (aka start site). But, it ...
another 'Homo sapien''s user avatar
11 votes

From which end of mRNA does transcription start?

They're both correct. The confusion stems from the book talking about the anticoding strand as well as the newly-formed coding RNA strand, whereas Khan Academy talks only about the coding strand. ...
Thymine's user avatar
  • 259
11 votes

why does translation occur more frequently than transcription?

The simple answer Under the assumption that each mRNA molecule is translated at least once, by necessity translation will happen more often than transcription. This is because the only way to get a ...
Maximilian Press's user avatar
8 votes

Do all proteins start with methionine?

When ribosomes create peptides, Methionine is the starting amino acid. But, in many proteins, Methionine Aminopeptidases cut it off from N-terminus. This happens in cases when methionine is not ...
YAHB's user avatar
  • 1,679
8 votes
Accepted

Can ribosomes read ssDNA?

Summary Messenger RNAs that are recruited to the ribosome for protein synthesis in vivo, need to satisfy particular structural requirements and must interact with the protein initiation factors that ...
David's user avatar
  • 26.2k
8 votes
Accepted

How can good Shine–Dalgarno or Kozak sequences enhance translation?

I would strongly recommend looking in more detail into available resources for SD and Kozak sequences, wikipedia basically answers these questions and has plenty of further reading if you desire to ...
Maximilian Press's user avatar
8 votes

Why are there two replicase proteins translated from tobacco mosaic virus RNA?

Short Answer As of 2021 the rationale for the production of two proteins from the Tobacco Mosaic Virus (TMV) replicase gene is incompletely understood. The two proteins share some activities but not ...
David's user avatar
  • 26.2k
8 votes

Why is the codon size three, rather than four?

The reason is pretty simple: It comes from the number of amino acids used to make proteins and thus with the necessary number of possible combinations and robustness of the system. We have 20 amino ...
Chris's user avatar
  • 51.7k
7 votes

Do two compatible tRNA codons bond together?

Yes, tRNA can form dimers. For example it was shown that E. Coli tRNA GCC forms homodimers, i.e. two identical molecules interact with each other. In this case the dimerization occurs between the anti-...
Ashafix's user avatar
  • 695
7 votes
Accepted

Is the start codon regarded as part of the UTR (untranslated region)?

Because the start codon is translated into methionine, it clearly can not be part of the 5'-untranslated region, as @Johnny writes in his answer. The more contentious question would be for the stop ...
David's user avatar
  • 26.2k
7 votes
Accepted

How do aminoacyl-tRNA synthases distinguish between similar amino acids?

Aminoacyl-tRNA sythetases are highly specific to their corresponding amino acid. First, the activation site, where the amino acid binds, constitutes a complex network of intermolecular interactions. ...
adjan's user avatar
  • 2,106
7 votes
Accepted

From which end of mRNA does transcription start?

@Thymine's answer is correct. I just thought I'd post a more graphic answer for clarity. ...
rotaredom's user avatar
  • 2,731
6 votes
Accepted

How does aminoacyl-tRNA synthetase recognize different tRNAs?

You give the answer in your question: binding areas that recognize a particular tRNA through unique identity sites at the acceptor stem and/or anticodon loop of the tRNA. The point is that ...
David's user avatar
  • 26.2k
6 votes
Accepted

How to determine the most likely reading frame of a DNA sequence?

This is what we classify as a homework question, but as it satisfies the criterion of the poster demonstrating an attempt to answer it, I provide the following suggestion of an answer. I assume that ...
David's user avatar
  • 26.2k
6 votes
Accepted

How to memorize Transcription and Translation?

I prefer a conceptual distinction rather than a mnemonic in this case. I've always thought of a transcript as an exact copy of record - that's the meaning of the word in English, and an RNA transcript ...
Bryan Krause's user avatar
  • 46.1k
6 votes

Does a gene need to be transcribed for every single protein made?

mRNA is not destroyed immediately after it is translated once. There can be multiple ribosomes translating a single strand of mRNA, as well. Depending on the regulation of the system, a single ...
MattDMo's user avatar
  • 15.3k
5 votes

Can mRNA be used by ribosomes more than once?

There are a few cases in translation that I can think of where an mRNA is translated more than once: the closed loop model of mRNA translation, translation reinitiation, and translation by polysomes. ...
jidicula's user avatar
  • 177
5 votes
Accepted

How much nucleoside triphosphate is required to form one peptide bond during protein synthesis?

Although the question shows considerable effort to achieve clarity, the way it is phrased as: How many molecules of nucleoside triphosphate… [does] it take to release enough energy still allows ...
David's user avatar
  • 26.2k
5 votes

Why is an initiator tRNA required, distinct from the methionine tRNA used in elongation?

I think the key to understanding this is to appreciate how different the initiation process is from the rest of translation. The 30S ribosomal subunit recognises start codons via an interaction with ...
Alan Boyd's user avatar
  • 22.8k
5 votes
Accepted

How to find the amino acid in the DNA protein

Then you just have to read the codon until you reach a stop codon. There are three stop codon UAA, UGA and ...
Remi.b's user avatar
  • 68.2k
5 votes

What percentage of our DNA is never transcribable? What percent is never actually transcribed into RNA unless researchers force it to in a lab?

While, as you say, most of our DNA can be transcribed, you are right that it is not well accessible and/or lacks strong promoters. It's said that over 80% of DNA is transcribed but only <2% ...
KaPy3141's user avatar
  • 1,597
4 votes
Accepted

Why does azithromycin not affect human mitochondria?

There are two general points that should be appreciated in relation to this question: Your statement that mitochondria “have prokaryotic ribosomes” is a misleading simplification. Although ...
David's user avatar
  • 26.2k
4 votes

Why is AUG the initiation codon?

From recent empirical research (Wang et al., 2018) on eukaryotes, basically the non-AUG start codons have context-dependent [translation initiation] efficiency, while AUG is a "sure thing", i.e. the ...
got trolled too much this week's user avatar
4 votes
Accepted

Relationship of the DNA of a eukaryotic gene to the 5'-UTR of its mRNA

Concise Answer The 5′-UTR region of a eukaryotic mRNA is derived from the RNA transcript of the region of a gene between the transcription start site and the DNA corresponding to the translational ...
David's user avatar
  • 26.2k
4 votes

Redundancy of the genetic code

You are correct in saying that Crick, in his Wobble Hypothesis, proposed that “the base on the third position of the codon and that on the anticodon need not be complementary”, but the “need not be” ...
David's user avatar
  • 26.2k
4 votes

How did the genetic code evolve?

It seems that duplicate codons make translation more robust and resistant to translational misreading. There are four theories that explain existence of duplicate codons: Stereochemical theory ...
Maxim Kuleshov's user avatar
4 votes

Are there any examples in nature of two polypeptides joining into a single, continuous, third polypeptide?

I am not aware of anything precisely corresponding to your diagram, but the somewhat related behaviour of inteins may be of interest in this respect. They are defined in Wikipedia as: An intein is ...
David's user avatar
  • 26.2k
4 votes

Translation of Poly-U in the Nirenberg and Matthaei experiment

This is an intelligent question that highlights the ‘sleight of hand’ simplifications employed in many text books to make experimental science appear cleaner and more logical than is in fact the case. ...
David's user avatar
  • 26.2k
4 votes

What is the Shine–Dalgarno sequence?

According to this Wikipedia article: "The Shine-Dalgarno (SD) sequence is a ribosomal binding site in bacterial and archaeal messenger RNA, generally located around 8 bases upstream of the ...
airhuff's user avatar
  • 290
4 votes

Why is an initiator tRNA required, distinct from the methionine tRNA used in elongation?

The same paper states the following just before the part you have quoted: The cell acquires an additional degree of control by having a separate tRNA for initiation, and thus regulates the levels ...
adjan's user avatar
  • 2,106

Only top scored, non community-wiki answers of a minimum length are eligible