We are writing General Biology 2, a specialized subject for STEM under K+12 curriculum. We are done with the first chapter, and right now, we are beginning with Chapter 2 which is on Genetics. We expect this part to require a lot of diagramming and pictures. We draw our own pictures by the way, and if we do copy from online sources, we copy only from creativecommons.org or from commons.wikipedia.org, and make the citations.
We wish to share with you some of our paragraphs for this chapter.
DNA structure
A DNA molecule is a double helix of two linear chains of nucleotides. The sugar component of the nucleotide is deoxyribose sugar, and its nitrogenous base can be either purines or pyrimidines. Deoxyribose and the phosphate molecule compose the backbone of DNA. By way of analogy, if DNA is a ladder, deoxyribose and the phosphate molecule are the vertical support of this ladder. The rungs are made from two complementary nitrogenous bases (purines and pyrimidines) attached to each other by hydrogen bond. The base pairings between nitrogenous molecules are adenine with thymine and cytosine with thymine.
Figure 2.2 DNA Structure
Complementary pairs of purines and pyrimidines are linked together by hydrogen bonds, while sugar-phosphate molecules on the sides are covalently bonded. A covalent bond, because it is formed by electron sharing, is a bond stronger than hydrogen bond. These differing strengths of bonding among molecules between the backbone and inward rungs of DNA cause the molecule to twist, giving the DNA its distinct double helix shape.
Figure 2.3 DNA and its Double Helix Shape
We wish to share with you some of our paragraphs for this chapter.
DNA structure
A DNA molecule is a double helix of two linear chains of nucleotides. The sugar component of the nucleotide is deoxyribose sugar, and its nitrogenous base can be either purines or pyrimidines. Deoxyribose and the phosphate molecule compose the backbone of DNA. By way of analogy, if DNA is a ladder, deoxyribose and the phosphate molecule are the vertical support of this ladder. The rungs are made from two complementary nitrogenous bases (purines and pyrimidines) attached to each other by hydrogen bond. The base pairings between nitrogenous molecules are adenine with thymine and cytosine with thymine.
Figure 2.2 DNA Structure
Complementary pairs of purines and pyrimidines are linked together by hydrogen bonds, while sugar-phosphate molecules on the sides are covalently bonded. A covalent bond, because it is formed by electron sharing, is a bond stronger than hydrogen bond. These differing strengths of bonding among molecules between the backbone and inward rungs of DNA cause the molecule to twist, giving the DNA its distinct double helix shape.
Figure 2.3 DNA and its Double Helix Shape