EVOLUTION OF CARBOHYDRATES

EVOLUTION OF AMAZING CARBOHYDRATES

The Stuff of Life

Plants and animals utilize a variety of basic materials to make the specialized parts that are so different in some ways.  Carbohydrates, proteins, and fats make up most of the volume of organic molecules and structures in the watery bath inside and/or outside the membrane bounded cells of living organisms.  Minerals make up a major part of vertebrate skeletal structures and of shells of some invertebrates.  Very important in proper functioning, and often controlling aspects of development and function, are vitamins, hormones, minerals, and trace elements in very small amounts. 

The hereditary material has a central role in perhaps most aspects of life, but little will be said about it in today’s blog.  DNA, RNA, and enzymes and the feedback mechanisms used are modified along with evolution of the things they control.

Glucose in plants versus animals

Glucose has an important role in utilization of stored energy in plants and animals.  But only a small amount can be tolerated in the cells of plants or animals.  Animals and plants can both burn it up as they metabolize it to produce energy by the same chemical pathways.  But too much in the cell would result in the cell bursting from water absorption that occurs by its diffusion into the cell from the watery bath around it.  Cells that survived are those that evolved to convert excess glucose into other compounds, especially large polymers such as cellulose in plants and glycogen in animals.

Plants can also store large amounts of glucose as starch as well.  Both cellulose and starch molecules are so large that only a few molecules can store hundreds of glucose molecules.  The generic name for such a large compound molecule is polymer.  Plants make glucose in abundance by the process of photosynthesis.  Glucose polymerized into cellulose makes a useful structural material, typically as the major part of the cell walls of plants. 

Cellulose processing was lost in the early cells that gave rise to the animal kingdom.  But animals developed a modified form of storage called glycogen that functions, as starch may do in plants at night, to quickly replace glucose when it becomes depleted in the cell from activity.

Glucose is a six carbon sugar.  Disaccharides are twelve carbon sugars such as sucrose, maltose and lactose; they are formed from particular combinations of two monosaccharides, such as glucose and fructose.  A five carbon sugar is part of the linking mechanism, for the chains forming DNA and RNA, along with one of the four purines and/or pyrimidines (adenine, cytosine, guanine, and thymine).  Each link of the chain with one of the four purines or pyrimidines uses three links at a time to code the hereditary processes of life.

A hypothesis about a balanced diet

We know that insulin helps the body in regulating blood glucose by somehow helping balance the role of storage and utilization between blood sugar and storage or release from fats and other stores.  Plants do not have insulin to my knowledge, but many of the chemical processes involved in storage and release of glucose may be similar. Varied grains, fruits, and vegetables in the diet are likely to provide some necessary substances involved in the process that are not fully known.  They and the fiber associated also provide a valuable role in maintaining the proper gut flora and fauna needed for healthy functioning of the lower digestive tract.

The first organic molecules

Organic molecules are commonly thought of as originating in living organisms.  But a few simple ones can form when lightning passes through a gaseous atmosphere containing water vapor, carbon dioxide, methane, and nitrogen.  Similar simple compounds can form in sea water exposed to red hot lava.  Both may have been important in contributing to the dissolved nutrients of seawater in early seas when the first life evolved.

Among those compounds formed in such circumstances are glucose, glycine, and adenine.  We have already discussed some of the role of glucose above.  Glycine and adenine are among simple amino acids utilized to make polymers, called proteins.  Additionally, adenine has an important role basic in ATP (adenosine tri-phosphate) for energy transfer processes in cellular metabolism.

The big picture

The above is just a rudimentary look at a portion of the processes and materials of life.  How they interact here is probably identical to how they have acted (and are or will act) in other comparable planets scattered throughout the cosmos.  Natural selection would probably produce great similarity of results through these remarkable chance directed processes that could only be controlled by an infinitely intelligent and powerful being.  It should be truly humbling to see that such a being has promised so much to us through his Son two thousand years ago.

Joseph G. Engemann      April 25, 2014