The following structure shows part of a polypeptide:
OH
I
COO–H I CH2– H
I I
N–C–C–C– H H
I I I
H COO– CH2–COOH
At a particular pH, an amino acid in solution can exist as ions that have both a negative and positive charge - VCE - SSCE Chemistry - Question 6 - 2009 - Paper 1
Question 6
The following structure shows part of a polypeptide:
OH
I
COO–H I CH2– H
I I
N–C–C–C– H H
I I I
H COO– CH2–COOH
... show full transcript
Worked Solution & Example Answer:The following structure shows part of a polypeptide:
OH
I
COO–H I CH2– H
I I
N–C–C–C– H H
I I I
H COO– CH2–COOH
At a particular pH, an amino acid in solution can exist as ions that have both a negative and positive charge - VCE - SSCE Chemistry - Question 6 - 2009 - Paper 1
Step 1
Name the amino acids that make up this section of the polypeptide:
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Answer
The amino acids present in the polypeptide section are
Serine
Glycine
Aspartic acid.
Step 2
Choose one of the amino acids in this section of polypeptide and draw the structure of its zwitterion clearly showing all bonds:
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Answer
For example, using Glycine:
H
|
H2N–C–COO⁻
|
H
In the zwitterionic form, glycine has a positively charged amino group (–NH3⁺) and a negatively charged carboxylate group (–COO⁻), which balances the overall charge.
Step 3
Give the names of two carbon compounds that can be used to synthesise this ester:
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Answer
The two carbon compounds that can be used for synthesising the ester in raspberry flavouring are:
