Lactic acid and alanine are both important chemicals in living systems. Their structures are Lactic acid: HOOC-CH(OH)-CH3 Alanine: H2N-CH(CH3)-COOH a. Give the name of the functional group common to both compounds. b. Why is alanine classified as an amino acid but lactic acid is not? c. In the boxes below, draw structures of two different possible organic molecules formed by a condensation reaction between lactic acid and alanine. d. For one of the structures given in part c., i. circle the new functional group formed and ii. name the functional group that you have circled.

SSCE VCE Chemistry Structure, Nomenclature, and Properties of Organic Compounds: Lactic acid and alanine are both

Lactic acid and alanine are both important chemicals in living systems - VCE - SSCE Chemistry - Question 2 - 2003 - Paper 1

Question 2

Lactic acid and alanine are both important chemicals in living systems. Their structures are Lactic acid: HOOC-CH(OH)-CH3 Alanine: H2N-CH(CH3)-COOH a. Give the ... show full transcript

Worked Solution & Example Answer:Lactic acid and alanine are both important chemicals in living systems - VCE - SSCE Chemistry - Question 2 - 2003 - Paper 1

Step 1

a. Give the name of the functional group common to both compounds.

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Answer

Both lactic acid and alanine contain the carboxyl group, represented as –COOH.

Step 2

b. Why is alanine classified as an amino acid but lactic acid is not?

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Answer

Alanine is classified as an amino acid because it contains both an amino group (–NH2) and a carboxyl group (–COOH) in its structure. In contrast, lactic acid only contains a carboxyl group and lacks the amino group.

Step 3

c. In the boxes below, draw structures of two different possible organic molecules formed by a condensation reaction between lactic acid and alanine.

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Answer

The first structure represents a dipeptide formed by the condensation of alanine and lactic acid:
1. The second structure could be an ester formed from the same reaction:

Step 4

d. For one of the structures given in part c.,

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Answer

i. Circle the new functional group formed: The new functional group formed in the dipeptide is a peptide bond (–CONH–).

ii. Name the functional group that you have circled: The circled functional group is a peptide bond.

Lactic acid and alanine are both important chemicals in living systems - VCE - SSCE Chemistry - Question 2 - 2003 - Paper 1

Worked Solution & Example Answer:Lactic acid and alanine are both important chemicals in living systems - VCE - SSCE Chemistry - Question 2 - 2003 - Paper 1

a. Give the name of the functional group common to both compounds.

b. Why is alanine classified as an amino acid but lactic acid is not?

c. In the boxes below, draw structures of two different possible organic molecules formed by a condensation reaction between lactic acid and alanine.

d. For one of the structures given in part c.,

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