Why do hydrophilic hormones last for a shorter time than hydrophobic hormones? They both lead to molecules directly activating or suppressing genes so why is this the case?
Hydrophobic hormones are often derived from steroids, which have a much more complex structure compared to peptide-based hydrophilic hormones. This means that hydrophobic hormones generally take a longer time to degrade compared to proteins, and its subsequent reactions it initiates would last longer.
Exceptions do apply due to the relative variation of hormones, and some hydrophobic hormones may last for a shorter time compared to some hydrophilic ones, it always depends.
You wouldn’t need to know the answer to this question for VCE biology.
I really like your reasoning Lifeisaconstantstruggle, but unfortunately it’s not quite correct.
The structural complexity of a molecule really makes little difference to how long the molecule will survive. If you take oxygen gas, as an example...it is an extremely simple structure, yet it is basically never degraded. So, unfortunately that line of thinking doesn’t hold up.
Peptide hormones have really short actions. Their influence is fleeting and they are rapidly degraded. Lipid hormones, however, remain active for a long period of time.
The reason for the difference has nothing to do with the molecules, but is actually all to do with the way cells deal with these hormones. Without going anywhere near the details, peptide hormones break down more quickly because that’s what cells do to them. Conversely, lipids stick around because that’s what cells do. These basically have to do with how long the hormone can stay bound to its receptor (which depends on the design of the receptor) and also whether there are many enzymes around to break them down.