Properties of Covalent Molecular Compounds.

• Low melting points and boiling points.
• Low enthalpies of fusion and vaporization These properties are usually one or two orders of magnitude smaller than they are for ionic compounds.
• Soft or brittle solid forms.
• Poor electrical and thermal conductivity.

Hydrogen bonds are responsible for specific base-pair formation in the DNA double helix and a major factor to the stability of the DNA double helix structure. A hydrogen-bond donor includes the hydrogen atom and the atom to which it is most tightly linked with.

The two strands are held together by hydrogen bonds between the bases, with adenine forming a base pair with thymine, and cytosine forming a base pair with guanine.

Cytosine and thymine are the two major pyrimidine bases in DNA and base pair (see Watson–Crick Pairing) with guanine and adenine (see Purine Bases), respectively.

Two purines and two pyrimidines together would simply take up too much space to be able to fit in the space between the two strands. This is why A cannot bond with G and C cannot bond with T. The only pairs that can create hydrogen bonds in that space are adenine with thymine and cytosine with guanine.

There are two differences that distinguish DNA from RNA: (a) RNA contains the sugar ribose, while DNA contains the slightly different sugar deoxyribose (a type of ribose that lacks one oxygen atom), and (b) RNA has the nucleobase uracil while DNA contains thymine.

So, the three main structural differences between RNA and DNA are as follows:

• RNA is single-stranded while DNA is double-stranded.
• RNA contains uracil while DNA contains thymine.
• RNA has the sugar ribose while DNA has the sugar deoxyribose.

Ribonucleic acid (RNA) is a molecule similar to DNA. Unlike DNA, RNA is single-stranded. An RNA strand has a backbone made of alternating sugar (ribose) and phosphate groups.

DNA has four nitrogen bases adenine, thymine, cytosine, and guanine and for RNA instead of thymine, it has uracil. Also, DNA is double-stranded and RNA is single-stranded which is why RNA can leave the nucleus and DNA can’t. Another thing is that DNA is missing an oxygen.

Yes, human cells contain RNA. They are the genetic messenger along with DNA. The three main types of RNAs are: Ribosomal RNA (rRNA) – present associated with ribosomes.

The central dogma of molecular biology suggests that the primary role of RNA is to convert the information stored in DNA into proteins.

DNA stands for deoxyribonucleic acid, sometimes called “the molecule of life,” as almost all organisms have their genetic material codified as DNA. Since each person’s DNA is unique, “DNA typing” is a valuable tool in connecting suspects to crime scenes.

double helix