# biology a level help

here is the full question. I've been trying to figure it out for a while. the link is below incase I missed out something, question 1.4.

The mutation that caused the CB allele was due to a 24 base-pair deletion from the CG allele.
the protein coded for by the CB allele is 306 amino acids long.
calculate percentage reduction in size of protein coded for by CB allele compared with protein coded for by CG allele.

https://filestore.aqa.org.uk/sample-papers-and-mark-schemes/2021/november/AQA-74023-QP-NOV21.PDF
bump !! i dont understand the first answer to be 2.55% to get the full marks
i only kinda get how to gain 1 mark ...
CB allele = 306 amino acids long - this is the length AFTER the deletion
24 base pairs = 8 amino acids (remember 1 codon of 3 base pairs = 1 amino acid)
CB allele + 8 amino acids = CG allele <- 314 amino acids long - this is the original length of DNA in the allele

8 (the size of the reduction/deletion) divided by 314 (the original length) = 0.025477707

Multiply this by 100 because it is a percentage, you get 2.55% to 3 sf.
Original post by Thestudent212955
here is the full question. I've been trying to figure it out for a while. the link is below incase I missed out something, question 1.4.

The mutation that caused the CB allele was due to a 24 base-pair deletion from the CG allele.
the protein coded for by the CB allele is 306 amino acids long.
calculate percentage reduction in size of protein coded for by CB allele compared with protein coded for by CG allele.

https://filestore.aqa.org.uk/sample-papers-and-mark-schemes/2021/november/AQA-74023-QP-NOV21.PDF

To calculate the percentage reduction in size of the protein coded for by the CB allele compared with the protein coded for by the CG allele, we need to determine the size difference between the two proteins and then calculate the percentage reduction.

First, we need to determine the size of the protein coded for by the CG allele. We are not given this information directly, but we know that the CB allele is a mutant version of the CG allele that has a 24 base-pair deletion. A gene is made up of a sequence of DNA nucleotides that code for amino acids, and three nucleotides code for one amino acid. Therefore, we can use the length of the CG allele sequence to estimate the length of the protein it codes for.

Assuming that the CG allele codes for a protein that is also 306 amino acids long (as stated for the CB allele), we can calculate the length of the CG allele sequence as follows:

Length of CG allele sequence = 306 amino acids × 3 nucleotides/amino acid = 918 nucleotides

With this information, we can now calculate the length of the CB allele sequence as follows:

Length of CB allele sequence = 918 nucleotides - 24 nucleotides = 894 nucleotides

Therefore, the CB allele codes for a protein that is 894 nucleotides long.

To calculate the percentage reduction in size, we can use the following formula:

Percentage reduction = (Initial size - Final size) / Initial size × 100%

where Initial size is the size of the protein coded for by the CG allele, and Final size is the size of the protein coded for by the CB allele.

Plugging in the values, we get:

Percentage reduction = (918 nucleotides - 894 nucleotides) / 918 nucleotides × 100%
Percentage reduction = 2.61%

Therefore, the percentage reduction in size of the protein coded for by the CB allele compared with the protein coded for by the CG allele is 2.61%.
thank you!
Original post by lily.m4e
CB allele = 306 amino acids long - this is the length AFTER the deletion
24 base pairs = 8 amino acids (remember 1 codon of 3 base pairs = 1 amino acid)
CB allele + 8 amino acids = CG allele <- 314 amino acids long - this is the original length of DNA in the allele

8 (the size of the reduction/deletion) divided by 314 (the original length) = 0.025477707

Multiply this by 100 because it is a percentage, you get 2.55% to 3 sf.
thank you so much!
Original post by Curious_Bilawi
To calculate the percentage reduction in size of the protein coded for by the CB allele compared with the protein coded for by the CG allele, we need to determine the size difference between the two proteins and then calculate the percentage reduction.

First, we need to determine the size of the protein coded for by the CG allele. We are not given this information directly, but we know that the CB allele is a mutant version of the CG allele that has a 24 base-pair deletion. A gene is made up of a sequence of DNA nucleotides that code for amino acids, and three nucleotides code for one amino acid. Therefore, we can use the length of the CG allele sequence to estimate the length of the protein it codes for.

Assuming that the CG allele codes for a protein that is also 306 amino acids long (as stated for the CB allele), we can calculate the length of the CG allele sequence as follows:

Length of CG allele sequence = 306 amino acids × 3 nucleotides/amino acid = 918 nucleotides

With this information, we can now calculate the length of the CB allele sequence as follows:

Length of CB allele sequence = 918 nucleotides - 24 nucleotides = 894 nucleotides

Therefore, the CB allele codes for a protein that is 894 nucleotides long.

To calculate the percentage reduction in size, we can use the following formula:

Percentage reduction = (Initial size - Final size) / Initial size × 100%

where Initial size is the size of the protein coded for by the CG allele, and Final size is the size of the protein coded for by the CB allele.

Plugging in the values, we get:

Percentage reduction = (918 nucleotides - 894 nucleotides) / 918 nucleotides × 100%
Percentage reduction = 2.61%

Therefore, the percentage reduction in size of the protein coded for by the CB allele compared with the protein coded for by the CG allele is 2.61%.