Cleaning the house is a purposeful duty. We remove the dirt, the waste, everything in the house that is of no use any further, and get rid of it.
Biology distinguishes itself from chemistry and rocks by the fact that almost everything that we encounter in life, is there for a purpose, for a specific duty, and for good reasons.
When scientists find a new organelle, molecule, or protein, one of the first questions is: What does it do? What is its purpose? What is it good for?
Making goal-oriented things is the hallmark of intelligent activity.
And the world of biochemistry is full of it.
Cleaning the house is necessary for our homes, and so in each of our living cells. Cells, in their non-stop business, produce tons of molecular waste. And that waste has to be disposed of. If there were no mechanisms to do so, one symptom would be for example Alzheimer's in our brains.
And the mechanisms doing the job of removing waste are truly formidable and extraordinarily advanced. Not only is waste removed, but also recycled through catabolism.
The make of nucleotides or amino acids, for example, de novo, is enormously complex. Recycling is so as well, but much less energy demanding.
This is done through autophagy. Autophagy plays a housekeeping role in removing misfolded or aggregated proteins, clearing damaged organelles, such as mitochondria, endoplasmic reticulum, and peroxisomes, as well as eliminating intracellular pathogens. Thus, autophagy is generally thought of as a survival mechanism
The term ‘autophagy’, derived from the Greek meaning ‘eating of self’, was first coined by Christian de Duve over 40 years ago, and was largely based on the observed degradation of mitochondria 1 Molecular circuitry and signaling pathways regulate autophagy. Autophagy is a complex self-degradative process. Furthermore, specific cargo is targeted for degradation. So even cleaning, and as a further step, apoptosis, cellular suicide, are processes directed by pre-programmed molecular processes.
Pre-programming is best explained by design.