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Please look at stereochemistry of anomeric carbon or carbon no. 1 of glucose unit.
Which among two is correct structure of lactose?
If, both are correct, then how?
Note : Image 1 is from Harper biochemistry
Both of the images are lactose. The first image is $\alpha$-lactose and the second is $\beta$-lactose. The difference between $\alpha$ and $\beta$ lactose is the orientation of the most right hydroxy (OH) group in the pictures.