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The structure of a section of a protein chain is shown in the diagram below: --N--C--C--C--C--C--C--C--C--C--C--C || || || || || || || || || O O O O O O O O O O H H H H H H H H H H \ / \ / \ / \ / \ / \ / H--C--C--C--C--C--C--C--C--C--C--C--C || || || || || || || || O O O O O O O O H H H H H H H H a - VCE - SSCE Chemistry - Question 8 - 2006 - Paper 1
Question 8
The structure of a section of a protein chain is shown in the diagram below: --N--C--C--C--C--C--C--C--C--C--C--C || || || || || || || || || O... show full transcript
Worked Solution & Example Answer:The structure of a section of a protein chain is shown in the diagram below: --N--C--C--C--C--C--C--C--C--C--C--C || || || || || || || || || O O O O O O O O O O H H H H H H H H H H \ / \ / \ / \ / \ / \ / H--C--C--C--C--C--C--C--C--C--C--C--C || || || || || || || || O O O O O O O O H H H H H H H H a - VCE - SSCE Chemistry - Question 8 - 2006 - Paper 1
Step 1
a. i. Circle the side chain group that is hydrophobic.
Answer
In the structure of the protein chain, the hydrophobic side chain group is represented by the hydrocarbon part of the amino acid side chain. This is typically a group consisting of carbon and hydrogen atoms, which do not interact favorably with water. Therefore, I would circle the hydrocarbon portion of the side chain.
Step 2
a. ii. Explain reasoning for hydrophobic groups in solution.
Answer
Hydrophobic groups would generally be expected to be situated in the interior of water-soluble proteins. This is because these groups do not interact favorably with water, and thus tend to be sequestered away from the aqueous environment. Conversely, hydrophilic groups, which can interact strongly with water, are found on the exterior. This arrangement minimizes the exposure of hydrophobic portions to water, stabilizing the overall structure of the protein.
Step 3
b. i. Draw the structure of amino acid with a carbon to nitrogen ratio of 3:1.
Answer
To derive the structure of an amino acid with a carbon to nitrogen ratio of 3:1, we begin with three carbon atoms and one nitrogen atom. The general structure can be written as follows:
H
|
NH2-
|
C-C-C
| | |
O O O
|| | |
H H H
This represents an amino group (NH2) connected to three carbon atoms.
Step 4
Step 5
c. Explain the chemical basis of the browning reaction.
Answer
The browning reaction in vegetables occurs through the enzymatic action of polyphenol oxidase (PPO). When vegetables are cut and exposed to air, enzymes interact with oxygen and phenolic compounds in the plant tissue, leading to the oxidation of phenols into quinones. These quinones are highly reactive, resulting in the formation of brown pigments called melanins. Boiling the vegetables denatures the enzyme, preventing the browning reaction because the enzyme is no longer able to catalyze the oxidation process.
Step 6