Final answer:
In humans, important gaseous metabolites or signaling molecules include nitric oxide, which acts by binding to intracellular receptors. Advanced research is also exploring how analyzing exhaled gases, which can act as biomarkers, might lead to early and non-invasive disease diagnosis using technologies like mass spectrometry.
Step-by-step explanation:
Yes, there are important gaseous metabolites or signalling molecules in humans. One notable example is nitric oxide, which has been identified as a signaling molecule with a variety of physiological roles, including vasodilation and neurotransmission. The mechanism of action for nitric oxide, being a gas, would likely involve binding to intracellular receptors (Answer: d. It binds to an intracellular receptor). Gaseous signaling molecules can diffuse rapidly across cell membranes and interact directly with intracellular targets, a property that differentiates them from other types of signaling molecules that bind to cell-surface receptors.
In addition to nitric oxide, there are other gaseous substances that can serve as biomarkers in the breath, which can indicate an organism's disease state or exposure to environmental pollutants. For example, analysis of molecules in exhaled breath has the potential to lead to early diagnosis of diseases such as asthma or lung cancer among others. Modern research, including work in Sangeeta Bhatia's lab at MIT, is focusing on identifying these biomarker "fingerprints" that could facilitate diagnosis through non-invasive methods like analyzing a patient's exhaled breath with advanced technologies such as mass spectrometry.