exons introns Transcription termination m Promoter site (also poly A site) Start
ID: 168958 • Letter: E
Question
exons introns Transcription termination m Promoter site (also poly A site) Start of transcription 50 ATG TAA 132 90 126 ATT 130 850 AUG in nucleotides) of the wild-type B-globin primary RNA transcript (initial a) (2 point) What is the length mRNA or before RNA splicing)? (Show your calculations to get credit) b) (2 point) How many amino acids are present in the wild-type B-globin protein? (Show your calculations to get credit) c) (3 point) Give the location of a mutation (ml) in the A-globin gene that would prevent RNA synthesis from the B-globin gene. Explain why. A base-pair substitution mutation (m2) indicated below, destroys the 3' splice site located in the first intron of the B-globin gene. exons Introns Transcription termination site (also poly A site) Promoter Start of r transcription TAA a 132 126 ATT 850 130Explanation / Answer
a) What is the length (in nucleotides) of the wild-type -globin primary RNA transcript (initial - mRNA or before RNA splicing)?
Answer: The numbers within the boxes indicate the length (in nucleotides) of each region.
The length (in nucleotides) of the wild-type -globin primary RNA transcript is equal to the lenght of the DNA sequences corresponding to the start of transcription and transcription termination.
Therefore, the length (in nucleotides) of the wild-type -globin primary RNA transcript = 50 + 90 + 130 + 222 + 850 + 126 + 132 = 1600
b) How many amino acids are present in the wild-type -globin protein?
Answer: The DNA sequences corresponding to the start codon and the stop codon are indicated. We know that three nucleotides togther form an aminoacid codon.
Therefore, the number of amino acids present in th e wild-type -globin protein= (Lenght of the DNA sequences from the start codon and the stop codon after splicing) / 3
= (90+222+126)/3 = 438/3 = 146
c) Give the location of a mutation (m1) in the -globin gene that would prevent RNA synthesis from the -globin gene.
Answer: Promoter
The promoter is not transcribed. The promoter of the gene is immediately upstream that is, immediately 5 to the start of transcription.
d) Would the m2 mutation increase, decrease or not change the length of the primary RNA transcript (pre-mRNA) made from the mutant -globin gene? Briefly explain your reasoning.
Answer: The m2 mutation would not change the length of the primary RNA transcript (pre-mRNA) made from the mutant -globin gene because the mutation occured before the spliced mRNA.
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