Biology STAAR (State of Texas Assessments of Academic Readiness) Practice Test

What elements are proteins primarily made of?

1. Carbon, hydrogen, and oxygen

2. Carbon, hydrogen, oxygen, and nitrogen

3. Carbon, hydrogen, oxygen, and phosphorus

4. Carbon, oxygen, nitrogen, and sulfur

The correct answer is: Carbon, hydrogen, oxygen, and nitrogen

Proteins are primarily made up of carbon, hydrogen, oxygen, and nitrogen. These elements play crucial roles in the structure and function of proteins. Carbon is a fundamental component of all organic molecules, including amino acids, which are the building blocks of proteins. Hydrogen and oxygen are also found in amino acids and contribute to the overall structure and behavior of proteins. Nitrogen is particularly important because it is a key part of the amino groups (-NH2) in amino acids, which distinguishes proteins from other macromolecules such as carbohydrates and lipids. Without nitrogen, proteins cannot be formed, as it is essential for the synthesis of amino acids. This distinguishes protein structure and function, allowing for the diverse roles proteins play in biological processes, including enzymes, hormones, and structural components of cells and tissues. Other elements like phosphorus and sulfur do have roles in biological systems but are not primary components of proteins, making this choice the most accurate.