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Suhani Marwadi posted an Question

May 10, 2021 • 02:51 am

30 points

IIT JAM
Biotechnology (BT)

How many different disaccharides containing the d- galactopyranose plus d- glucopyranose are possible?

how many different disaccharides containing D- galactopyranose plus D- glucopyranose are possible?

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Abhijeet Gaurav

It would be mentioned because of this thing only. But the Real answer would be 19 only. As one molecule is a repetition.
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A
Abhijeet Gaurav

Yes you are right. But if you look carefully here then a-(1-1)-b & b-(1-1)-a are same structure that is {a,b-trehalose} that's why there are written 20 possibilities it's just 19 here because of repetition of one.
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ok sir that means correct answer is 19?actually in materials provided by eduncle answer is given 20 that's why I asked.
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A
Abhijeet Gaurav

Correct answer is 19. D-glucopyranose exists in both α and β forms. The glycosidic bond can be formed between the anomeric hydroxyl group on one glucose unit and any hydroxyl group on the other glucose unit. The possible linkages are: # α-Glucose + α-Glucose α-(1→1)-α [trehalose] α-(1→2) [α-kojibiose] α-(1→3) [α-nigerose] α-(1→4) [α-maltose] α-(1→6) [α-isomaltose] # α-Glucose + β-Glucose α-(1→1)-β [α,β-trehalose] α-(1→2) [β-kojibiose] α-(1→3) [β-nigerose] α-(1→4) [β-maltose] α-(1→6) [β-isomaltose] # β-Glucose + α-Glucose β-(1→1)-α [but this is the same as α-(1→1)-β] β -(1→2) [α-sophorose] β -(1→3) [α-laminaribiose] β -(1→4) [α-cellobiose] β -(1→6) [α-gentiobiose] # β-Glucose + β-Glucose β-(1→1)-β [β,β-trehalose] β -(1→2) [β-sophorose] β -(1→3) [β-laminaribiose] β -(1→4) [β-cellobiose] β -(1→6) [β-gentiobiose] So there are 19 possible disaccharides of D-glucopyranose plus D- galactopyranose.
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Sir 20 hue na total to answer 20 hona chahiye na?
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