The two ring forms of glucose _____. Help?

Question

The two ring forms of glucose _____.

Answer: arise because the hydroxyl group at the point of ring closure can be trapped in either one of two possible positions.

Can somebody explain it to me? This will benefit my studying purposes for my AP bio test on the first day of school. Thanks!

Answer 1

go to: http://en.wikipedia.org/wiki/Glucose

and look at the diagrams for

1)The chain form of D-glucose

2)α-D-glucopyranose

3)β-D-glucopyranose

when in the chain form, the c2-c1 bond can rotate.

once it locks up, the #1 carbon can have its -OH in what's called a cis or a trans position, it just depends upon were it was at the time.  

aove the wikipedia diagrams is a good explanation