Draw Haworth formulae of ∝ - D -galactose and β - D -galactose.

The sugars can be written using Haworth's formula. Pyranose and Furanose are the oxides rings that resemble the oxygen-containing heterocyclic ring pyran and furan respectively. Galactose has molecular formula is C 6 H 12 O 6 . The Haworth formulae of ∝ - D -galactose and β - D -galactose are as follows : Here, the two structures shown above are all similar except at the C - 2 carbon atom. In α-D-galactose the hydroxyl ion below the plane and β-D-galactose the hydroxyl ion is above the plane.

Draw Haworth formulae of ∝ - D -galactose and β - D -galactose.

The sugars can be written using Haworth's formula. Pyranose and Furanose are the oxides rings that resemble the oxygen-containing heterocyclic ring pyran and furan respectively. Galactose has molecular formula is C 6 H 12 O 6 . The Haworth formulae of ∝ - D -galactose and β - D -galactose are as follows : Here, the two structures shown above are all similar except at the C - 2 carbon atom. In α-D-galactose the hydroxyl ion below the plane and β-D-galactose the hydroxyl ion is above the plane.

Tryptophan and histidine have the structures I and II respectively. Classify them into neutral/acidic/basic ∝ -amino acids and justify your answer. (Hint: Consider involvement of lone pair in resonance).

Amino acids are the fundamental building blocks of proteins containing an amino group and a carboxyl group. The acidic amino acids contain an additional carboxyl group in their structure, whereas, the basic ammo acids contain an additional amino group in their structure. In neutral amino acids, the number of amino groups are equal to carboxyl groups. The compounds given are : Compound I and II are having more amino groups than carboxyl groups, therefore,these are basic amino acids.

Compare the molecular masses of the following compounds and explain the observed melting points. Formula Molecular mass Melting point 89 293 . 5 o C C 5 H 11 - NH 2 87 - 55 o C C 3 H 7 - COOH 88 - 7 . 9 o C

α -amino acids have relatively higher melting points than the corresponding amines or carboxylic acids of comparable molecular mass. α -amino acids act as zwitter ions or dipolar ions. Due to this dipolar salt-like structure, they have strong dipole-dipole interactions. Therefore, their melting points are higher than the corresponding amines or carboxylic acids which do not exist as zwitter ions.

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Chemistry Standard 12>Chapter 14 - Biomolecules>Use your brain Power>Q •

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Draw Haworth formulae of $\propto$ - $D$ -galactose and $β$ - $D$ -galactose.

Important Questions on Biomolecules

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Chemistry Standard 12>Chapter 14 - Biomolecules>Use your brain Power>Q •

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N

-methyl acetamide. What is the name of the functional group in this compound?

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Chemistry Standard 12>Chapter 14 - Biomolecules>Can you recall ?>Q •

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Chemistry Standard 12>Chapter 14 - Biomolecules>Use your brain Power

Tryptophan and histidine have the structures $(I)$ and $(II)$ respectively. Classify them into neutral/acidic/basic $\propto$ -amino acids and justify your answer. (Hint: Consider involvement of lone pair in resonance).

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