Smell molecular structure

Some animals, and especially insects, rely on what amounts to a sense-of-smell for communication with others of their species. Substances synthesized by a particular species, and used to send messages in this way, are called pheromones. Many of these substances have rather simple molecular structures because they must be reasonably volatile and yet they are remarkably specific... 

The molecular structures of vanillin (4-hydroxy-3-methoxybenzaldehyde), isovanillin (3-hydroxy-4-methoxybenzaldehyde) and ethylvanillin(3-ethoxy-4-hydroxybenzaldehyde) were determined by Egawa et al. (2006) by means of gas electron diffraction. Among them, vanillin and ethylvanillin have a vanilla odour but isovanillin smells different. Vanillin and isovanillin have two stable con-formers and ethylvanillin has four. 

Molecular structure is also central for those molecules used as a means of communication. Examples of chemical communication occurring in humans are the conduction of nerve impulses across synapses, the control of the manufacture and storage of key chemicals in cells, and the senses of smell and taste. Plants and animals also use chemical communication. For example, ants lay down a chemical trail so that other ants can find a certain food supply. Ants also warn their fellow workers of approaching danger by emitting certain chemicals. 

Taste and smell are well-known chemical senses however, the specific genes and proteins involved in some tastes have not yet been fully identified. SEE ALSO Artificial Sweeteners Molecular Structure Neurotransmitters. 

The case of supervenience highlights the role of empirical chemical research in establishing at least some aspects of the relation between microscopic and macroscopic systems. One educational implication would then involve an emphasis on the significant role of empirical research in chemical inquiry. As an example educational scenario, the question of supervenience can be raised at secondary education through case studies investigating the relationships between the colour, smell and texture, and microscopic properties such as molecular structure and bonding. 

Smells occur when volatile compounds stimulate receptors in our noses. There is a tremendous variety of such compounds, and they display a great diversity of molecular structures. But many of the smells we encotmter in our fridges are due to volatile fatty acids — for example, when butter goes rancid, it releases butyric acid, which has a particularly foul smell. Bases neutralize acids. Baking soda, or sodium bicarbonate, is a base. It reacts with butyric acid to form sodium butyrate, which has no smell because it isn t volatile. 

In the current chemical literature one among the few concepts that are so frequently used is aromaticity [1,2], The term aromaticity was initially associated with certain properties, in particular with smell or perfumed. Lloyd and Marshall [3, p. 87] elegantly condense this term as the term aromatic was interpreted at different times in terms of molecular structure, of reactivity and of electronic structure, and, in consequence, there has been much confusion over its precise meaning and definition. We suggest that because of this confusion, it would be better if the use of the term aromatic was discontinued, safe perhaps with its general and original connotation of perfumed, and that it should pass with other technical terms which have outlived their precision and usefulness to the realm of the historian of chemistry. ... 

It should already be obvious that the initial "selection" of chiral starting material whether it was L-amino acids, D-sugars, or their chiral precursors, set life on a path in which chiral molecular structures play a critical role. The biochemistry of life requires an ability to recognize specific molecular structures (most of which are chiral), and then to initiate specific biochemical responses. In this chapter we will describe some general properties of chiral recognition, and then discuss the importance of molecular chirality on smell, taste, and other aspects of chiral molecular interactions. 

It should be clear that an appreciation of the importance of chiral molecular structure and the discrimination and control provided by the interactions of chiral molecules is now essential for anyone interested in understanding insect pheromones, smell, taste, and, of course, biochemistry. In the next chapter we will discuss the critical importance of chirality in an area that impacts our lives in ways more direct than insect communication, namely, pharmaceuticals. 

There are a number of similarities between ammonia and amines that carry beyond the structure. Consider odor. The smell of amines resembles that of ammonia but is not as sharp. However, amines can be quite pungent. Anyone handling or working with raw fish knows how strong the amine odor can be, since raw fish contains low-molecular-weight amines such as dimethylamine and trimethylamine. Other amines associated with decaying flesh have names suggestive of their odors putrescine and cadaverine. 

The sense of smell challenges chemical understanding. On the one hand, given the structure of a new molecule a chemist can predict its spectroscopic properties over a wide domain of electromagnetic frequencies. A mixture ordinarily displays a spectrum that superimposes the spectra of its individual components, unless they physically interact with each other. In the chemical senses, on the other hand, perceptions of mixtures often cannot be inferred from their constituents, even though the components do not interact at the molecular level. Moreover, no one can reliably predict the organoleptic properties (taste or smell) of a new molecule from its structure. Even if... 

Molecular bonding and structure play the central role in determining the course of chemical reactions, many of which are vital to our survival. Most reactions in biological systems are very sensitive to the structures of the participating molecules in fact, very subtle differences in shape sometimes serve to channel the chemical reaction one way rather than another. Molecules that act as drugs must have exactly the right structure to perform their functions correctly. Structure also plays a central role in our senses of smell and taste. Substances have a particular odor because they fit into the specially shaped receptors in our nasal passages, and taste is also dependent on molecular shape. 

This chapter describes the functioning of the five major senses— smell, taste, vision, hearing, and touch—on a molecular level. All are shown to rely on mechanisms involved in transduction of other sorts of signals (hormones, neurotransmitters, etc.). Olfaction, taste, and vision utilize G-protein-linked 7TM receptors. Hearing and touch have different receptors but appear to share ankyrin repeats as part of their structures. 

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