An example of a common alternative conception:
The compound ATP, adenosine triphosphate, is an important metabolite that is often said to enable metabolic processes because it has energy-rich, or high energy, phosphate bonds that release energy when broken. However, bond fission always requires an energy input, and the bonds in ATP, like all chemical bonds, therefore require energy to break.
The term 'energy rich' bonds (still sometimes seen in textbooks) seems to be understood by many learners to suggest that the bonds somehow store energy that can be released when they break. The particular bonds concerned (those between the phosphate groups in ATP) are better understood as weak bonds that have low bond enthalpy, and so break relatively easily.
The term 'high energy bonds' is strictly not incorrect as these bonds are at a higher energy than many other chemical bonds. However this can easily be misunderstood – it is like referring the sea bed in the English channel as being at a 'high altitude' as it is not as deep as that in the middle of the Atlantic Ocean. In that sense, as a sea bed, it is indeed 'high altitude', in the sense that it is not as deep below sea level as many other sea beds. Understanding the term 'high energy bonds' therefore requires appreciating that high energy bonds still have a negative energy level, but they are not as negative in energy level as many other chemical bonds. Another analogy might be to refer to someone with debts of a thousand pounds as a rich debtor as they have much less debt (negative capital) than many other people who are in debt.
This conception can be considered a specific example of a more general misconception that chemical bonds store energy – but in the case of ATP it may be seen as an exception even by learners who know bonds normally need to 'take in' energy before they break.
[Please be aware that a word may have different nuances, or even a different meaning, according to context.]« Back to Index
