Question

refer to the table below. three different proteins were isolated from the same bacterial cells and their biological activity measured. each protein was then subjected to 10 - minute periods of increasing temperature, followed by measurement of biological activity. the results are shown in the table. based on these data, which statement is correct?
options:

• interactions between r groups in protein a add up to greater stabilization of tertiary structure than interactions between r groups in protein b or protein c
• secondary structure in protein b is weaker than secondary structure in protein a or protein c
• protein b contains no disulfide bonds, whereas proteins a and c likely contain disulfide bonds
• protein b is smaller than proteins a or c, giving it fewer amino acid r groups that can interact to stabilize its tertiary structure

Explanation:

To determine the correct statement, we analyze the data:

• First statement: The data shows Protein A's activity drops faster than Protein B or C at higher temps, implying weaker tertiary stabilization for A, so this is incorrect.
• Second statement: Secondary structure (like alpha - helices, beta - sheets) is stabilized by H - bonds. Protein B loses activity at lower temps than A and C, suggesting its secondary structure is more sensitive (weaker) to heat, so this is correct.
• Third statement: Disulfide bonds (covalent) stabilize tertiary structure. Protein B loses activity earlier, but the data doesn't directly indicate disulfide bond presence/absence. Protein C also loses activity, so this is not supported.
• Fourth statement: Protein size (amino acid number) isn't related to R - group interactions for tertiary structure from the given data. This is not supported.

Answer:

The correct statement is "Secondary structure in Protein B is weaker than secondary structure in Protein A or Protein C." (The option with this text, likely the second option in the original multiple - choice setup)