From Simple to Complex?
Every form of life contains about 80% water, because the first living cells originated in water. The complex molecules that characterize living organisms are made up of simpler molecules that constitute the basic building blocks of life:
- Simple sugars, the cell’s preferred energy source, are stored in long chains of complex sugars.
- Fatty acids are the molecules from which cell membranes are made.
- Proteins, which form the structure of cells and promote certain essential chemical reactions, are composed of chains of 20 different smaller molecules called amino acids. These protein chains can be several hundred amino acids long, and are twisted together in a unique way that gives that protein its function.
- The genetic material in each cell contains the coded instructions for all of its components. It is the only part of the cell that can replicate itself. The basic building blocks for this genetic material are called nucleotides.
- The long chains of DNA are combinations of only two different nitrogenous nucleotide base-pairs.
Living organisms are made up of the same molecules that compose non-living matter. In organic molecules these components are often arranged circularly, like pentagons or hexagons. If so, they additionally contain information stored within the electrons running through these circuits.
They mostly contain the basic elements such as carbon, oxygen, hydrogen and nitrogen atoms. Appreciable amounts of calcium, phosphorus, potassium, sulfur, magnesium, and sodium can be found.
B-DNA
Z-DNA
A-DNA
B-DNA: the right-handed typical form of DNA in which the strands twist up and to the right. It has about 10 base pairs per helical turn and two helices on its surface, rotating individually at 36°.
Z-DNA: the left-handed unstable, uncommon form of DNA in which the strands twist up and to the left. It has about 12 base pairs per helical turn and two helices on its surface, rotating as pairs at 60°.
A-DNA: a wider right-handed spiral, with a shallow, wide minor groove and a narrower, deeper major groove. The A form may be produced in hybrid pairings of DNA and RNA strands in a cell, as well as in enzyme-DNA complexes.
C-DNA: a single stranded form of DNA artificially synthesized from a messenger RNA template and used in genetic engineering to produce gene clones.
Segments of DNA where the bases have been chemically modified by methylation may undergo a larger change in conformation and adopt the Z or one of the 20+ other forms.
