Genetics Help. Please answer all completely. 3. Th indicate the length in nucleo
ID: 254999 • Letter: G
Question
Genetics Help. Please answer all completely.
3. Th indicate the length in nucleotides of each region. e genomic structure of human beta globin is shown below. The numbers within the boxes i) what is the length (in nucleotides) of the wild-type ?-globin primary transcript (pre-mRNA)? i) How many amino acids are present in the wild-type ß-globin protein? b) Give the location of a mutation (ml) in the ß-globin gene that would prevent RNA synthesis from the ß-globin gene. c) A base-pair substitution mutation (m2) indicated below, destroys the 3' splice site located in the first intron of the ß-globin gene. - exous -nrons Transeription termination Promoter Start of transeription m2 site (also poly A site) ATG 50 90 130 850 132 5' 120 "A" of codon AUG is +51 128 nt from first nt of exon 3 to first "A" of codon TAA i) Would the m2 mutation increase, decrease or not change the length of the primary RNA transcript (pre-mRNA) made from the mutant p-globin gene? Briefly explain your ii) Would the m2 mutation Increase, decrease or not change the length of the mature RNA transcript made from the mutant B-globin gene? Briefly explain your reasoning.Explanation / Answer
3. a. i) The length of wild type ?-globin primary RNA transcript is – [50+90+130+222+850+132] = 1474nt.
ii) Number of amino acids that are present in wild type ?-globin protein is – [90+222+128] = 440 nt.
b. A mutation m1 in the ?-globin gene that would prevent RNA synthesis from ?-globin gene may occur before 50 nucleotides or in the promoter region. Because if occurs in the promoter region RNA polymerase cannot bind properly, as a result transcription does not start properly.
c. i) m2 mutation does not change the length of the primary RNA transcript. Because in primary transcript, both introns and exons are present. Base substitution mutation just substituted the existing base with another base. So the length becomes unchanged.
ii) m2 mutation increases the length of the mature RNA transcript. Because mutation occurs at the 3’ splice site of the first intron, so this intron might not be spliced during splicing.
8. a. 24 nucleotides code for the given wild-type protein sequence.
As there are 8 amino acid and each amino acid coded by 3 nucleotide codon, so there are 24 nucleotides.
b. In case of mutation 1:- Single base substitution mutation. Because if we consider the the codon for fourth lysine is AAA, the middle A might be substituted with G to produce arginine.
In case of mutation 2 :- Nonsense mutation has occur. Because the amino acid chain has stopped after 3rd amino acid.
In case of mutation 3:- Single base substitution mutation. Because if we consider the the codon for fourth lysine is AAA, the middle A might be substituted with U to produce isoleucine.
In case of mutation 4:- Frameshift mutation. Either insertion or deletion total frame of amino acids has changed.
c. The codon for the lysine at the fourth position - AAA. Because from mutation 1 and 3 it is clear that middle A is substituted with either G or U. from these two cases the codon of the fourth lysine has cleared.
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