Which biological molecule does not contain a phosphate group? phospholipid triglyceride nucleic acid ATP phosphorylated molecule
The Correct Answer and Explanation is:
Correct Answer: Triglyceride
Explanation
Biological molecules often contain specific functional groups that define their structure and function. Among the options provided—phospholipid, triglyceride, nucleic acid, ATP, and phosphorylated molecule—the triglyceride is the only one that does not contain a phosphate group.
Triglycerides are a type of lipid composed of one glycerol molecule bonded to three fatty acids through ester bonds. This structure is entirely non-polar and hydrophobic, making triglycerides excellent for long-term energy storage in animals. Importantly, triglycerides lack a phosphate group, distinguishing them from other lipid types like phospholipids.
In contrast, phospholipids consist of a glycerol backbone attached to two fatty acid tails and one phosphate group, which is often further linked to a polar head group. This phosphate-containing structure gives phospholipids amphipathic properties, allowing them to form cellular membranes.
Nucleic acids (DNA and RNA) are polymers of nucleotides, each made up of a sugar, a nitrogenous base, and at least one phosphate group. The phosphate groups form part of the backbone of nucleic acid structures, connecting sugars in adjacent nucleotides through phosphodiester bonds.
ATP (adenosine triphosphate) is the primary energy carrier in cells and contains three phosphate groups. These high-energy phosphate bonds release energy when broken, powering cellular processes.
A phosphorylated molecule is any molecule that has had a phosphate group added to it, typically through an enzymatic reaction. Phosphorylation is a common way to regulate proteins and enzymes in cells.
Thus, while all the other listed molecules contain one or more phosphate groups integral to their structure or function, triglycerides do not. Their structure is based solely on glycerol and fatty acids, with no involvement of phosphorus, making them the correct answer.
