AngelT
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AngelT wrote:
Could someone explain me?
Thanks a lot! ; )
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| study_ing
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not really..
coz u havent given the genetic diagram with it !!
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| study_ing
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oh i got it...sorry
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| study_ing
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is the anwer c..dont wanna expalin something wrong to u so wanna make sure im right
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| study_ing
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wait it cud be a..
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| new_n_lost
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the ans for Q 3 is easier as u have to only look at the small graph below the family graph the disease causing allele is dark in color so the fetus will have Marfan syndrome n for Q 4 u wold have to refer to the Chap 4 in the notes
can u plz tell which Edition r u using
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| new_n_lost
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the ans for Q 3 is easier as u have to only look at the small graph below the family graph the disease causing allele is dark in color so the fetus will have Marfan syndrome n for Q 4 u wold have to refer to the Chap 4 in the notes
can u plz tell which Edition r u using
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| study_ing
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try figuring out the alleles each one has got..remember in this cast u cant say simply whether the upper or lower band is normal. u have to conclude it. sit with a pen and label the different ppl ( u'll get faster with time, dont worry)
II-3 is diseased
II-4 is not. His alleles are definitely normal.
III-I is normal. Hence II-3 is a heterozygote whose normal allele is inherited by 111.1
111.2 has got the abnormal allele( upper band) and one normal( lower one) from her dad.
IV -1 has got one normal allele from his dad …from his mom he has gotten the upper band which in her case is the abnormal allele.
Hence the answer is a.
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| study_ing
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label the alleles too...a for abnormal, n for normal.
( since im done with dtep 1 i didnt do that ...hence i guessed at c)
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| AngelT
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Thanks study_ing and new_n_lost!
I am using 2001 edition and these are review questions from chapter 7 (Genetic Testing).
What about the question 4? I didnt understand why is it splice-donor..how could I differenciate from splice- acceptor?
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| AngelT
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What about the question 4? I didnt understand why is it splice-donor..how could I differenciate from splice- acceptor?
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| blueocean
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splice sites are boundaries between exons and intron and are 2 types:the border going from exon to intron is called a donor site (5') and the border separating intron from exon is called an acceptor (3') .
But I didn't find anywhere what means a mutation in those splice sites. I think those kind of mutation means defective exons no absence of the entire exons like in this question.
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| blueocean
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I really don't know the answer at second question because both (nonsense and frameshift mutation) could determine deletion of the exon.
Nonsense mutation = a mutation that alters a gene so as to produce a truncated product
Frameshift - the insertion or deletion of a nucleotide causing a disruption of the translational reading frame
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| AngelT
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The answer is D (Splice-donor mutation)...so this is my doubt because in this question there is substitution of 3' end of exon 2...so it should be Splice-acceptor mutation...am I wrong?
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| study_ing
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sorry cant help u there...was confused with this myself..
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| study_ing
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but kaplan is usually correct with its answers...no matter how wrong they may seem..we pbly need to think harder..
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| AngelT
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"the border going from exon to intron is called a donor site (5') and the border separating intron from exon is called an acceptor (3')"..so the substitution in this question it is in the end of exon 2..so if we draw it..we can get
5'.. Exon1 Intron1 Exon2 Intron2 .. 3'..so maybe Kaplan is right..Splice-donor mutation ..Hehe ; )
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| blueocean
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I just find the real answer- if you have a mutation in the donor splicing site the spliceosome will have 3 posibilities:
[- to find a similar sequence in the introns and to remove just a piece of intron
[- to find a similar sequence in the exons and to remove a part of exon
-to use the next splicing site which means will "read" the exon like intron and will remove the ENTIRE exon ( like in mutation in bglobin gene in bthalasemia)
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| blueocean
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AngelT wrote:
"the border going from exon to intron is called a donor site (5') and the border separating intron from exon is called an acceptor (3')"..so the substitution in this question it is in the end of exon 2..so if we draw it..we can get
5'.. Exon1 Intron1 Exon2 Intron2 .. 3'..so maybe Kaplan is right..Splice-donor mutation ..Hehe ; )
I just find the real answer- if you have a mutation in the donor splicing site the spliceosome will have 3 posibilities:
[- to find a similar sequence in the introns and to remove just a piece of intron
[- to find a similar sequence in the exons and to remove a part of exon
-to use the next splicing site which means will "read" the exon like intron and will remove the ENTIRE exon ( like in mutation in bglobin gene in bthalasemia)
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| emhava
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I have a problem with Q 3 discussed above. Can someone tell me please how can I-2, II-2, III-1, all have the upper (larger) fragment responsable for the disease still to remain unaffected although it is a dominant pattern???
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