What are the internal blocks or rungs of the DNA ladder?

Answer 1

The four nitrogen bases, Guanine, Cytosine, Thymine, and Adenine. Thymine and Cytosine are pyrimidines and Guanine and Adenine are purines. Thymine bonds with Adenine and Cytosine bonds with Guanine.

Answer 2

DNA (deoxyribonucleic acid) consisits of two main parts: the backbone, and the rungs of the ladder. The backbone of DNA is its supporting structure, and is made up of alternating molecules of sugar and phosphate. The entire structure is a double helix, double because of the two backbones, one on each side of the rungs.

The second component of DNA is the rungs of the ladder. Each rung is connected to a sugar molecule on the backbone, and the rung itself is made up of two nitrogen bases. There are four different bases: thymine, adenine, guanine, and cytosine, as opposed to RNA, which also has four bases but substitutes Uracil for thymine. The "Base-Pair Rule" is that each base can only pair with one other base. Adenine can only pair with thymine to form a rung and guanine can only pair with cytosine. One suger molecule, a phosphate and ONE of the the bases makes up a nucleotide.

Great websites for info on DNA and RNA are http://www.biologycorner.com/worksheets/DNAcoloring.html and

http://www.eurekascience.com/ICanDoThat/dna_structure.htm

Answer 3

the base pairs

The rungs of the DNA ladder are formed by nucleotides (Adenine with Thymine, and Guanine with Cytosine) bonded together with Hydrogen bonds.

Answer 4

The rungs that are in the DNA ladder molecule are nucleotides. They are adenine, guanine, thymine and cytosine. Deoxyribose and phosphate make up the backbone of the molecule.