The following is a segment of the template strand of human...

The following is a segment of the template strand of human BRCAl gene: ACA TAT TIT GCA AAT TIT GCA a. Write the corresponding mRNA segment. b. Write the three-letter and one-letter abbreviations for the corresponding peptide scgment. c. If there is a point mutation in the second nucleotide triplet and $\mathrm{C}$ replaces $\mathrm{A}$, what is the change, if any, in the amino acid sequence?

The following is a segment of the

template strand of human BRCAl gene:
ACA TAT TIT GCA AAT TIT GCA
a. Write the corresponding mRNA

segment.
b. Write the three-letter and one-letter

abbreviations for the corresponding

peptide scgment.
c. If there is a point mutation in the second

nucleotide triplet and $\mathrm{C}$

replaces $\mathrm{A}$, what is the

change, if any, in the amino acid

sequence?

Key Concepts

DNA Transcription

Transcription is the process by which a segment of DNA is used as a template to generate a complementary RNA sequence. In eukaryotic cells, this involves the synthesis of messenger RNA (mRNA) using RNA polymerase, where the base pairing rules are applied with uracil replacing thymine. This process is fundamental to gene expression, as the resulting mRNA carries the genetic information from the nucleus to the ribosome for protein synthesis.

Genetic Code and Codon Translation

The genetic code is a set of rules that defines how the sequence of nucleotides in mRNA is translated into the sequence of amino acids in proteins. Every group of three nucleotides, known as a codon, corresponds to a specific amino acid or a stop signal during translation. The translation process involves the conversion of mRNA codons into amino acids, which are often represented using both three-letter and one-letter abbreviations in protein sequences.

Point Mutation

A point mutation is a change in a single nucleotide in the DNA or RNA sequence. This type of mutation can alter a single codon, potentially changing the amino acid it codes for during translation. Depending on where the mutation occurs and the nature of the nucleotide change, the result can be a substitution of one amino acid for another, which may affect the structure and function of the protein.

Silent Mutation

A silent mutation is a specific type of point mutation where a change in the nucleotide sequence does not alter the amino acid composition of the protein. This occurs because the genetic code is degenerate, meaning that multiple codons can encode the same amino acid. As a result, even though the mRNA sequence is modified, the peptide sequence remains unchanged.

Transcript

00:01 Hello there students.

00:01 Today we're going to be answering this question in regards to a chapter on nucleic acid and protein synthesis and for this we're going to be focusing on the section on viruses.

00:18 So for this one, they want their the following segment is a template strand of the human brca1 gene, which you see right in front of your screen.

00:30 They want to want you to write a corresponding mrna sequence and then write a three letter and one letter abbreviations for the corresponding peptide segment and also they have another question they have for you they're wondering if there is a point of mutation in the second nucleotide tripletes and and c replaces a, which is why i changed the blue.

01:06 What is the changes if there's any change in the amino acid sequence? you can pause the video, drop down your answers, and we'll go over this shortly.

01:20 Okay, so for the setup, let, you know, when we do this, just like remember, a is equal to t and c is equal to g.

01:29 Okay you got it let me change you this okay so basically when we see this we see that this is a t g t and this is a a t and we'll just continue on so that will be done so there we go we got our setup so now after this is a setup that we got for dna, they want us to write a corresponding m rna sequence, i mean segment.

02:24 So to write that, we're going to go by this setup and jot it down.

02:30 But when we're doing m rna, what's the change when it comes down to the rna? rna has no t.

02:46 Rna has a u so instead of so with that instead of a equaling to t it's a equal to you all right just to make sure um as a is aware of what's what so then with a now we have made a different color and we have a different color and we have it a, c, a, u, a, u, c, c, a, u, c, c, a, so that is our m rna segment.

03:57 So now, based off of the m rna segment, they want to write a three letter and one letter abbreviation for the corresponding peptide.

04:07 So we're going to follow with this segment right here, which i write it down.

04:15 Okay, i don't want to keep writing down one over and over.

04:22 Okay, so i think i'll overdate it with the undo button...

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