Organic macromolecules play a major role in our body. Nucleic acids are one class of such macromolecules that have a very significant role to play.
They are the ones that are responsible for various biosynthetic activities that are carried out in the cellular level. They are also the ones that are responsible for carrying genetic information from one generation to another.
In this write-up on nucleic acids facts, we will learn a lot. It is going to an information-packed article. So, gear up!
Nucleic Acids Facts: 1-9 | The Basic Info
Classes of Macromolecules
1. In total, there are four classes of macromolecules present in body. They are:
Polysaccharides are polymeric (a polymer is a large molecule, usually known as macromolecule that is composed of many repeated subunits) carbohydrates that are composed of monosaccharaide units’ chains.
One of three macronutrients are Fats. A fat molecule consists mainly of hydrogen and carbon atoms and is hydrophobic.
Proteins are large macromolecules that contain one or more than one long chains of amino acid residues. They are responsible for a wide range of functions in organisms.
They are a type of macromolecules responsible for performing a wide range of functions including carrying genetic information from generation to generation.
Nucleic Acids: Component Breakdown
2. Nucleic acids are very complex macromolecular organic compounds that are essential for existence of life.
3. Nucleic acids are actually polymers nucleotides.
A polymer is a large molecule which is made by joining small molecules known as monomers. The term ‘Polymer’ is derived from two Greek words ‘Poly’ which means ‘many’ and ‘Mer’, which means ‘unit.’
4. A nucleotide in turn contains nucleoside and phosphoric acid.
5. A nucleoside in turn consists of nitrogen bases and pentose sugars.
6. There are two types of nitrogen bases. They are:
- Purines: There are two types of purines. They are adenine and guanine.
- Pyrimidines: There are three types of pyrimidines. They are thymine, cytosine and uracil.
7. Now, pentose sugars are also of two types. They are:
- Ribose: This particular pentose sugar is present only in RNA.
- Deoxyribose: This particular pentose sugar is present only in DNA.
8. RNA or Ribose Nucleic Acid is present only in the cytoplasmic matrix.
9. DNA or Deoxyribose Nucleic Acid is present only in the cell nucleus (except during mitosis and meiosis).
Nucleic Acids Facts: 10-14 | History
10. DNA was first discovered in 1869. A Swiss physician named Friedrich Miescher was the one who discovered it while working in the laboratory of Felix Hoppe-Seyler – a German physiological chemist.
11. Miescher used hydrochloric acid to treat white blood cells obtained from pus found on bandages from Franco-Prussian War.
12. He obtained nuclei by treating the white blood cells using HCl or hydrochloric acid.
14. He called the precipitate ‘nuclein’ because it was obtained from the nuclei.
Nucleic Acids Facts: 15-19 | History
15. Later investigations revealed that the precipitate was acidic in nature. It is because of this reason that the name was changed from nuclein to nucleic acid. Miescher really did not know that he had discovered DNA.
16. Hoppe-Seyler managed to get a similar precipitate from yeast cell. That precipitate is now known as RNA.
17. It was Emil Fischer who identified the pyrimidines and purines in the year 1880.
18. Albercht Kossel identified the nitrogenous bases, pentose sugar and phosphoric acid of nuclein.
19. The name ‘nucleic acid’ was suggested by Altmann in 1899. He used the term to describe nuclein that contained phosphorus.
Nucleic Acids Facts: 20-24 | History
20. Kossel was awarded Nobel Prize in 1910 because he demonstrated the presence of cytosine and thymine (the two pyrimidines) and adenine and guanine (the two purines) in nucleic acids.
21. Kossel’s work along with investigations from Jones, Levine and Ascoli during the first quarter of 1900s eventually revealed that there are two types of nucleic acids. They are:
- Deoxyribonucleic Acid or DNA
- Ribonucleic Acid or RNA.
22. Rossenbeck and Feulgen developed DNA-specific staining techniques in 1924.
23. Feulgen eventually used these techniques to demonstrate that most of the DNA content of a cell is present inside the cell nucleus. He demonstrated this in 1937.
24. A. R. Todd was the one who eventually found in the 1950s that there was inter-nucleotide bond.
Nucleic Acids Facts: 25-33 | Nucleosides
25. A nucleoside consists of one pentose sugar one heterocyclic nitrogen base. So, a nucleoside is made up of either a ribose and a heterocyclic nitrogen base or, a deoxyribose and a heterocyclic nitrogen base.
26. A glycosidic bond is responsible for connecting a pentose sugar to a nitrogen base.
A glycosidic bond is a covalent bond that joins a carbohydrate molecule to another molecule which may or may not be a carbohydrate.
A covalent bond is a chemical bond which includes the sharing of electron pairs between atoms.
27. The names of nucleosides are derived from the names of the nitrogen bases. For example, in case of RNA, a ribonucleoside which contains the nitrogen base adenine is named as ‘adenosine’.
28. Similarly, ribonucleosides that contain guanine, uracil and cytosine are named as guanosine, uridine and cytidine respectively.
29. In case of DNA, a deoxyribonucleoside which contains the nitrogen base adenine is named as deoxyadenosine.
30. Similarly, deoxyribonucleosides that contain guanine, cytosine and thymine are named as deoxyguanosine, deoxycytidine and deoxythymidine respectively.
31. Thymine rarely occurs in ribonucleosides. This is the reason why deoxythymidine is usually referred to as thymidine.
32. Pyrimidine and purine bases are often abbreviated using single letters. Those abbreviations are also used for ribonucleosides. The abbreviations are:
- A for Adenosine
- G for Guanosine
- U for Uridine
- C for Cytidine
33. Deoxyribonucleosides also have abbreviations and they are:
- dA for Deoxyadenosine
- dG for Deoxyguanosine
- dC for Deoxycytidine
- dT for Deoxythymidine
Nucleic Acids Facts: 34-35 | Nucleotides
34. Nucleotides contain nucleosides and phosphoric acid (in form of phosphate groups).
35. The name of a ribonucleotide or a deoxyribonucleotide is dependent on the nucleoside. The name also indicates the number of phosphate groups present in the nucleotide.
EXAMPLES OF NAMES OF NUCLEOTIDES:
Nitrogen Base: Adenine
Ribonucleotide: Adenosine Monophosphate (AMP) – this indicates that there is only one phosphate group in the Adenosine Monophosphate.
Nitrogen Base: Adenine
Deoxyribonucleotide: Deoxyadenosine Monophosphate (dAMP) – this indicates that there is only one phosphate group in Deoxyadenosine Monophosphate.
Nucleic Acids Facts: 36-41 | DNA
36. DNA or Deoxyribose Nucleic Acid or Deoxyribonucleic Acid consists of a pentose sugar, adenine, guanine, cytosine and thymine and phosphate groups.
37. The phosphate group (which is a part of nucleotide) is attached to the pentose sugar with help of phosphodiester bond.
38. Erwin Chargaff found some regularities in nucleotide compositions found in DNA samples that he extracted from various eukaryotic and prokaryotic cells.
39. Chargaff also observed that in the DNA of any given cell, the adenine and thymine are present in equimolar amounts. He also saw that the guanine and cytosine are also present in equimolar amounts.
40. In the DNA of all species, the ratio of pyrimidines to purines is 1:1. In other words, molar ratio of DNA is A+G = C+T.
41. Watson and Crick proposed the double helical structure of DNA in the year 1953.
Nucleic Acids Facts: 42-47 | DNA
42. The two people, i.e., Watson and Crick could do so because of the following:
- The know structures of nucleotides.
- The X-Ray diffraction patterns that were obtained from DNA fibers. The patterns were obtained by Maurice Wilkins and Rosalind Franklin.
- The chemical equivalence that Chargaff noticed.
43. The DNA model given by Watson and Crick account for the equal amounts of pyrimidines and purines.
44. This accounting of equal amounts of pyrimidines and purines suggested that DNA has two strands.
45. The two strands are arranged antiparallely and the bases of one strand paired specifically with the bases of the another strand.
46. Adenine pairs with thymine while guamine pairs with cytosine in DNA.
47. The model that Watson and Crick gave is now known as B conformation of DNA or just B-DNA.
Nucleic Acids Facts: 48-50 | RNA
48. While DNA is completely genetic, different types of RNA are actually non-genetic.
49. RNA are single stranded but they usually have complex secondary structures.
50. There are four major classes of RNA. They are:
Ribosomal RNA or rRNA
rRNA are molecules and they are present in the Ribosome. They are the most abundant group or class of RNA. They make up about 80% of the total cellular RNA.
Transfer RNA or tRNA
tRNA are responsible for transporting amino acids to Ribosome to be incorporated into the peptide chains during protein synthesis. They are not very long (only 73-95 nucleotides long). They make up nearly 15% of total cellular RNA.
Messenger RNA or mRNA
mRNA are responsible for helping in the encoding the sequence of amino acids in proteins. mRNA carry the information from DNA to the translation complex (a place where proteins are synthesized). They make up only 3% of total cellular RNA. Of all RNA classes, mRNA are the least stable ones.
These molecules are present in all cells. Some of the small RNA molecules have catalytic activities or the contribute to catalytic activities in association with proteins. These are non-coding RNA molecules.
Did you know? RNA can become double-stranded! Single-stranded nucleotides fold back and become double-stranded. There are many RNA viruses that are double-stranded. Some of the examples of the family of RNA viruses are Reoviridae, Chrysoviridae, Endornaviridae, etc. They usually cause severe gastroenteritis.
Nucleic Acids Facts: 51 | Differences Between DNA and RNA
|1. Pentose sugar in DNA is known as deoxyribose.||1. Pentose sugar in RNA is known as ribose.|
|2. Nitrogen bases present are:|
(a) Purines – adenine and guamine.
(b) Pyrimidine – cytosine and thymine.
|2. Nitrogen bases present are:|
(a) Purines – adenine and guamine
(b) Pyrimidine – cytosine and uracil
|3. Molecules have four nucleotides:|
(a) deoxyadenosine monophosphate.
(b) deoxyguanosine monophosphate.
(c) deoxycytidine monophosphate.
(d) deoxythymidine monophosphate.
|3. Molecules have four nucleotides:|
(a) adenosine monophosphate.
(b) guanosine monophosphate.
(c) cytidine monophosphate.
(d) uridine monophosphate.
|4. DNA is double-stranded with nucleotides arranged in pairs.||4. RNA is single-stranded|
|5. DNA is genetic material.||5. RNA is carrier of genetic information and plays a very important role in protein synthesis mechanism.|
|6. DNA is seen in chromosomes, chloroplasts, mitochondria, nucleoplasm, etc.||6. RNA is seen in cytoplasm, nucleolus, nucleoplasm etc.|
|7. DNA can get damaged by Ultraviolet radiation.||7. RNA is relatively resistant to Ultraviolet radiation.|
|8. DNA has C-H bonds. These bonds make DNA fairly stable.||8. The O-H bonds present in ribose of RNA makes it more reactive compared to DNA.|
|9. Body destroys those enzymes that can attack the DNA. The double-stranded helix structure has very small groves that provide protection to the DNA because there isn’t ample space for enzymes to attach and cause damage.||9. In alkaline conditions, RNA is not stable. Also there are large grooves in the molecules that make RNA susceptible to attacks by enzymes.|
|10. DNA is self-replicating.||10. RNA is synthesized from DNA as and when required.|
Nucleic Acids Facts: Functions of DNA and RNA
52. DNA stores genetic information.
53. It is responsible for replication of genetic material.
54. DNA helps in evolution of life because of mutation of DNA.
55. RNA is catalytic in nature. RNA performs functions of few enzymes like ribozyme. RNA is far more reactive than DNA.
56. Transcription (the process of copying DNA to RNA) and translation (process of using RNA to produce proteins) are two important functions performed by RNA.
Did you know? RNA is considered to be the first self-replicating molecule that exists!
P.S. Verma and V. K. Agarwal. Cell Biology: Nucleotides and Nucleic Acids. pp. 200-207