Draw the Haworth projection of beta-D-sorbose Fischer projection below. n pr CH,0H ?? ?? ?? CH20H Show your work Sorbose is a ketose aldose puranose furanose disaccharide oligosaccharide polysaccharide Cellulose is a homopolysaccharide of what monomer units? 1 pt
The correct answer and explanation is:
Haworth Projection of β-D-Sorbose from its Fischer Projection
To draw the Haworth projection of β-D-sorbose from its Fischer projection, we follow these steps:
Step 1: Analyze D-sorbose structure
D-sorbose is a ketose sugar (a monosaccharide with a ketone group) with six carbons. Its Fischer projection includes:
- Carbon 1: Part of the ketone group.
- Carbon 2: Has the configuration defining the D-series.
- Carbons 3–5: Hydroxyl (-OH) and hydrogen (-H) groups attached, determining chirality.
- Carbon 6: Terminal CH2_2OH group.
Step 2: Cyclization
- D-sorbose typically forms a furanose (5-membered ring) structure due to the reaction of the hydroxyl group on Carbon 5 with the ketone group on Carbon 2.
- This cyclization creates a new stereocenter at Carbon 2, forming two anomers: α and β. The β-anomer has the anomeric -OH group on the same side as the CH2_2OH group in the Haworth projection.
Step 3: Draw the Haworth projection
- Orient the ring with the oxygen at the top right.
- Place the CH2_2OH group above the ring at Carbon 5.
- Place the -OH group on Carbon 2 above the plane (β-form).
- Assign positions for the -OH groups on Carbons 3 and 4 based on the Fischer projection:
- -OH on Carbon 3 is below the plane.
- -OH on Carbon 4 is above the plane.
- Add the CH2_2OH group at Carbon 1 below the plane.
Sorbose Classification
- Ketose: Contains a ketone group.
- Furanose: Forms a 5-membered ring.
- Monosaccharide: Simplest sugar unit.
Cellulose Structure
Cellulose is a homopolysaccharide consisting of β-D-glucose units. These units are linked by β(1→4) glycosidic bonds. It forms linear chains that aggregate into microfibrils, giving structural integrity to plant cell walls.
Explanation of β-D-glucose in Cellulose:
- Each glucose unit alternates orientation (180° rotation) to allow hydrogen bonding between adjacent chains.
- This arrangement makes cellulose strong, insoluble, and ideal for structural purposes.
- Humans lack the enzyme cellulase to break β(1→4) linkages, making cellulose indigestible.
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