Scientists Have Found That Polypeptides Which Are Normally Synthesized in the Endoplasmic

question 26

Multiple Choice

Scientists have found that polypeptides which are normally synthesized in the endoplasmic reticulum are about 20 amino acids longer when they are synthesized by ribosomes not attached to the endoplasmic reticulum. What is a possible explanation for the greater length of these polypeptides?

• A) Ribosomes attached to the endoplasmic reticulum require fewer amino acids to function.
• B) The 20 amino acids serve as a signal (peptide) sequence that directs the forming polypeptides to the endoplasmic reticulum, where they are cleaved off during processing.
• C) The 20-amino-acid sequence helps the endoplasmic reticulum package these proteins for shipping to the Golgi.
• D) The protein has a different function in the cytosol than in the endoplasmic reticulum.

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Definitions:

Biased Sample

A sample that does not accurately represent the population from which it was drawn, often leading to skewed results.

Population

A group of individuals of the same species living and interbreeding within a given area.

Independent Variable

The variable that is manipulated or changed in an experiment to test its effect on the dependent variable.

Statistically Significant

A term in statistical hypothesis testing used to denote that the results obtained are unlikely to have occurred by chance, at a specified level of significance.