Consider the following segment of mRNA produced by the...

Consider the following segment of mRNA produced by the normal order of DNA nucleotides: ACA UCA CGG GUA a. What is the amino acid order produced from this mRNA? b. What is the amino acid order if a point mutation changes UCA to ACA? c. What is the amine acid order if a point mutation changes CGG to GGG? What happens to protein synthesis if a point mutation changes UCA to UAA? e. What is the amino acid order if an insertion mutation adds a $\mathrm{G}$ to the beginning of the mRNA segment? f. What is the amino acid order if a deletion mutation removes the $A$ at the beginning of the mRNA segment?

Consider the following segment of

mRNA produced by the normal order of

DNA nucleotides:
ACA UCA CGG GUA
a. What is the amino acid order produced

from this mRNA?
b. What is the amino acid order if a point

mutation changes UCA to ACA?
c. What is the amine acid order if a point

mutation changes CGG to GGG?
What happens to protein synthesis if a

point mutation changes UCA to UAA?
e. What is the amino acid order if an

insertion mutation adds a $\mathrm{G}$

to the beginning of the mRNA segment?
f. What is the amino acid order if a

deletion mutation
removes the $A$ at the beginning of the

mRNA segment?

Key Concepts

Insertion and Deletion Mutations (Frameshifts)

Insertion and deletion mutations involve the addition or removal of nucleotides in the mRNA sequence. When these changes are not in multiples of three, they shift the reading frame of the codons, leading to frameshift mutations. Such mutations can drastically alter the amino acid sequence downstream from the mutation site and often result in nonfunctional proteins due to widespread changes in the encoded peptide.

Stop Codon and Nonsense Mutations

Stop codons are specific codons in the mRNA sequence that signal the end of translation. When a point mutation transforms a codon into a stop codon, this is called a nonsense mutation, which typically results in the production of a truncated, often nonfunctional, protein due to early termination of the translation process.

Genetic Code and Codons

The genetic code consists of nucleotide triplets known as codons, each of which corresponds to a specific amino acid or a stop signal during translation. This standard code is universal among many organisms and ensures that the mRNA's nucleotide sequence is reliably translated into the correct protein sequence.

mRNA Translation

mRNA translation is the biological process by which the information encoded in messenger RNA is converted into a sequence of amino acids during protein synthesis. This process occurs in the ribosome, where each set of three nucleotides, called a codon, directs the incorporation of a specific amino acid into the growing polypeptide chain.

Point Mutations

Point mutations involve single nucleotide substitutions within the DNA or RNA sequence. They can have different outcomes depending on their location and nature: silent mutations may not affect the protein at all, missense mutations result in a different amino acid, and nonsense mutations can produce a stop codon leading to premature termination of protein synthesis.

Transcript

00:01 Okay, this question says that we have the following segment of mrna produced by the normal order of dna nucleotates.

00:08 The following is going to be the mrna sequence.

00:14 Okay, it is ac, a, u, c, a, u, c, g, g, g, u .s.

00:26 Okay.

00:26 Okay, remember that in mrna we have to arrange them as codons, it means as triplets of nucleotize.

00:32 Here we have one column, for example, another column, another column, another column.

00:35 And this arrangement is useful because according to the genetic code, each column is going to code for a specific amino acid.

00:44 Okay.

00:45 For example, if we use the genetic code, we're going to see that aca, this column, codes for the amino acid threone.

00:57 Okay.

00:58 Also, this uca is going to code for the amino acid serene and this colonel here cgg is going to code for the amino acid arguing and finally this g ua is going to code for the amino acid valine so our normal amino acid sequence is going to be trionine serine arguing and vali okay question a says what is the amino acid order produced from this mrna well this is okay this is going to answer question a question b says, what is the amino acid order if a point mutation changes uca to aca, okay? so instead of uca we're going to have aca now.

01:47 So this is going to remain the same also this and also this.

01:51 This codon, aca, according to the genetic table that you can find in google, aca is going to code for the amino acid threone in two.

02:01 Okay? okay, so practically you're going to have three on and three on and okay, trioning.

02:10 So practically, question b is asking, what is the amino acid order if a point mutation changes uca to aca? well, the amino acid sequence is going to be, trionine, trigon, arguing, argating, and valid.

02:24 Okay, in these answers, question b.

02:27 Question c says, what is the am amino acid order if a point mutation changes cgg to gg? okay, let's stay in blue, gigi, okay.

02:42 And according to the genetic code, gggg is going to code for the amino acid glyc.

02:51 Okay, so, practically the amino acid that we're going to have, the amino acid sequence that we're going to have, that is change of cgg by gg is theronein, serine, glising, and value.

03:07 Okay? and this is going to answer question c.

03:11 Question d, it says, what happens to protein synthesis if a point mutation changes uca, this uca to uaa.

03:24 Okay, let's state it here again.

03:28 Aca, uca, cg, and g, and g ua.

03:32 It says, what happens if we change uca to uaa? okay, uaa according to the genetic code is stop columns...

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