Biological complexity: how cell structure functions (Introduction)

by David Turell , Sunday, November 06, 2016, 00:38 (2720 days ago) @ David Turell

The endoplasmic reticulum is a highly complex network of membranes that holds the internal cell structure together, but is moveable for passage of molecules:

https://www.sciencenews.org/article/scientists-need-redraw-picture-cells-biggest-organe...

"The ER is a snaking network of membranes that stretches from the nucleus of the cell to its edge. A sort of cellular jack-of-all-trades, it provides scaffolding for protein-producing ribosomes and makes sure those proteins are folded properly. It churns out lipids. And it stores and releases calcium, which sends messages within and between cells. Endoplasmic reticulum stress or malfunction can contribute to neurodegenerative diseases like Alzheimer’s and Parkinson’s.

"Scientists have peered at this organelle under microscopes many times before. But newer super-resolution microscopy techniques reveal details just tens of nanometers wide, far smaller than what conventional microscopes can see. That resolution upgrade showed that apparently flat sheets of membranes actually consisted of dense clusters of tubules vibrating and shifting.

"Instead of being made of a mixture of sheets and tubes, the outer region of the ER turns out to be made mostly just of tubes.

"Those tiny tubules come together in three-way junctions, linking into a mesh network that resembles a stretchy spider web. When the ER needs to move into a new part of the cell, the tubes can expand or contract. And the junctions can also slide up and down the tubes like curtains on a rod, the team found.

“'You can’t pull a sheet apart very easily except by breaking it,” Lippincott-Schwartz says, but the tubes are far more adaptable.

"The tubes are packed to different densities throughout the ER, perhaps reflecting the various jobs that different parts of the sprawling organelle take on.

"The team still saw bona fide sheets in the part of the ER closest to the cell’s nucleus, a feature other scientists have also reported. Those sheets were stacked on top of each other like pancakes."

Comment: These cells are a wet environment in which manufacture of protein products is constant. The structure molecules must react with shifting and folding rapidly and automatically in response to stimuli. Within these molecules there is no thinking involved, just automatic changes in form and shape. The protein scaffolding must be pliant to allow for movement within the cell of the reactive molecules, while the protein components of the cell must give way simultaneously and synchronously. This describes a protein factory in which everything is moving, both the manufacturing machines and the interior of the factory itself. It is reasonable that the first living cells were like this. How did that all happen at once? Only if planned by a mind, that is, by God.