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Does the last nucleotide in a codon have less specificity than the others and if so why?
Wiki User
∙ 13y ago
Yes, this is true (generally speaking). In many cases there are two different codons that differ at the third position yet code the same amino acid.
I hypothesize that the reason that this is so is that nature has naturally selected the codons to be resistant to certain transition and transversion mutations.
transition mutation = purine to purine or pyrimidine to pyrimidine
transversion mutation = purine to pyrimidine or pyrimidine to purine
Wiki User
∙ 13y ago
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What kind of mutation is this ugu-ccg-GAA-cga to ugc-cgg-GAA-cga?
The sequence TGA-GCC-ATG-A is changed in 2 places to become TGA-GCA-CAT-GA.When one base is changed, it is called a point mutation.In this case, a GCC in the DNA has been changed to a GCA. This would mean the mRNA codon (coded for by this DNA) would change from CGG to CGU.Both of these codons code for the same amino acid - Arginine. Therefore this type of point mutation is known as a silent mutation.The extra C that appears would be called an addition mutation, which is a type of frameshift mutation.
Put the following structures in order from smallest to biggest, Chromosome, Genome, Nucleotide Base, Codon, Gene, Cell Nucleus?
atombase subunitnucleotidesgenechromosomenucleuscellAnd also, DNA is totally sweet if you learn about it. Ya 'know? Just take the time to read your book instead of Google searching everything, ok Justin?!
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The last step is reading the termination codon which will release the protein.
What meaning do the first and last codons have for protein synthesis?
Codons are used for making amino acids. Some codons will tell the ribosomes to start tell the tRNA to make the amino acids or to stop making amino acids. I like to think of the start/initiator/promoter codon(AUG) as a capital letter in a sentence and the stop/terminator codons(UAA, UAG, and UGA) as periods in a sentence.
What is the amino acid sequence for a DNA strand with the base sequence DNA-AGGTAGAT?
Serine, Isoleucine. Last codon is incomplete.
If an mRNA is made up of 60 bases how many codons does it contain and how many amino acid does it code for?
A codon is exactly three bases long, so an mRNA strand with 60 bases would contain 20 codons. The first codon will encode for methionine (this is called the "start" codon) and the last codon will be a "stop" codon, which does not encode for an amino acid. Thus, an mRNA strand of 60 bases will code for 19 amino acids. Keep in mind, it is possible for a stop codon to be anywhere on the mRNA strand, and when a stop codon reaches the ribosome, translation must stop. For example, if an mRNA strand contained 30 codons, and the 15th were a stop codon, the mRNA would only code for 14 amino acids and then be done. The other 15 codons would go untranslated.
Which mRNA codons will start the process of translation?
If you're referring to stop codons, then there are three: UAA, UAG and UGA. They do indeed stop translation, though I wouldn't say they halt ribosomes. Stop codons code for a releaser enzyme, one that fits the A site of the ribosome, but does not carry an amino acid. This enzyme cuts the bond between the polypeptide and the last tRNA.
Does last mean come before all others?
No, "Last" means come after all others. "First" means come before all others.
What is the maximum number of amino acids that could be coded for by a sextion of mrna with the sequence guucagaacugu?
A codon is three bases long - so this section of mRNA would have 4 codons; UGA-UUC-AGU-AAC.Each codon relates to a specific amino acid (but several codons can code for the same amino acid, for example both UUU and UUC code for the amino acid Phenylalanine).Normally if you have four codons, such as this section of mRNA, the maximum number of amino acids you could have would be four. However, the first codon in this section, UGA, is actually a STOP codon. This means that when the ribosome reaches this codon, no further amino acids will be joined.This means that no amino acids could be coded for with this section of mRNA. (If the order of the codons was reversed, making the STOP codon last, then the answer would be three).
What does a codon code for?
A stop codon signals the end of an amino acid chains A STOP codon marks the end of a segment of DNA that is to be transcribed. During transcription, a molecule of messenger RNA (mRNA) is synthesized. The base sequence of this RNA is determined by the base sequence of the template strand of the DNA being transcribed.When the transcription process reaches a STOP codon, that codon is the last to be transcribed. The mRNA therefore ends with a STOP codon. By convention, the gene is considered to be the base sequence on the non-template strand of DNA, and there are three STOP codons: TAA, TGA, TAG. Any one of these marks the end of the gene.The corresponding STOP codons in mRNA are: UAA, UGA, UAG.Mitochondria contain DNA, with 37 genes. In animals, mitochondrial DNA uses TGA (UGA in the mRNA) to code for one of the amino acids, tryptophan, and not as a STOP codon. Plant mitochondria use the "standard" code, with three STOP codons.
Do different levels of hurricanes last longer then others?
In many cases the stronger storms last longer than others, but there is no strict relationship.
