Nucleic Acids: Structure & Function

This assignment delves into the crucial functions of nucleic acids, DNA, and RNA, in living systems. It outlines their structures – primary, secondary, tertiary, and quaternary – emphasizing the double helix structure of DNA and various RNA configurations. The text highlights how nucleic acids store and transfer genetic information, enabling replication, transcription, and protein synthesis through mRNA, tRNA, and rRNA. Mutations and phenotypic alterations are also discussed within the context of genetic material.

Running head: FUNCTIONS OF NUCLEIC ACIDS IN LIVING SYSTEMS
FUNCTIONS OF NUCLEIC ACIDS IN LIVING SYSTEMS
Name of the Student
Name of the University
Author Note

1FUNCTIONS OF NUCLEIC ACIDS IN LIVING SYSTEMS
Nucleic acids refer to the deoxyribonucleic acids and ribonucleic acids. These are termed
as DNA and RNA. The structures of both DNA and RNA are similar but RNA has a ribose
sugar, while DNA has a deoxyribose sugar. The structure of nucleic acids can be divided into
primary, secondary, tertiary and quaternary structures.
The primary structure is a linear nucleotide sequence held together by phosphodiester
bonds. Nucleotides consist of nitrogenous bases like adenine, guanine, cytosine, thymine (for
DNA) or uracil (for RNA). Apart from nitrogenous bases, nucleotides consist of five-carbon
sugars and phosphate groups. The nitrogenous bases form a glycosidic bond with the 1’-OH
groups of both ribose and deoxyribose. The phosphate groups form ester bonds with the 5’-OH
groups of the sugar. DNA is double stranded, while RNA is single stranded (Egli and Saenger
2013). The secondary structure of DNA consists of a double helix. The two strands of DNA in
the double helix is held together by hydrogen bonds. The nucleotides of one strand forms
hydrogen bonds with the nucleotides of the adjacent strand. However, the guanine cytosine
pairing is carried out by three hydrogen bonds, while two hydrogen bonds are present between
adenine and thymine (Jeffrey and Saenger 2012).
The hydrogen bonds are weaker compared to the other strong bonds holding the two
strands together. These include the stacking interactions between bases. The stacking interactions
are stabilized by hydrophobic interactions and Vander Waals interactions. The secondary
structure of RNA consists of helices, bulges, loops, among others. The most common secondary
structure of RNA is the hairpin or stem loop structure. The tertiary structure of a DNA double
helix consists of B-DNA, A-DNA and Z-DNA. The quaternary structure of nucleic acids
involves higher levels of organizations like chromatin, which involves interaction of nucleic
acids with small proteins called histones.

2FUNCTIONS OF NUCLEIC ACIDS IN LIVING SYSTEMS
Figure 1: Hydrogen and sugar phosphate bonds in the DNA helical structure.
(Source: Opentextbc.ca 2017)
Nucleic acids constitute the genetic material of all living beings. It is involved in the
storage and subsequent transfer of genetic information. DNA undergoes replication and in turn
helps in the transfer of genetic information from one generation to another generation
(O’Donnell, Langston and Stillman 2013). RNA on the other hand is involved in protein
synthesis. The genetic material of the living organism carries all information for making an
identical organism. The genetic material consists of a variety of genes that when expressed help
to determine the phenotypic traits of an organism. Mutations in the genes can give rise to various
phenotypic alterations. While DNA undergoes replication, transcription process helps in the
synthesis of RNA from DNA. While the function of DNA is storage of genetic information, the
function of RNA is transfer of genetic information from nucleus to the cytoplasm in order to
enable translation or protein synthesis with the help of ribosomes.

3FUNCTIONS OF NUCLEIC ACIDS IN LIVING SYSTEMS
RNA can be classified into messenger RNA (mRNA), ribosomal RNA (rRNA) and
transfer RNA (tRNA). After transcription, mRNA is found to be complementary to the DNA
template strand. It consists of genes or genetic messages, which undergo translation in the
cytoplasm to produce protein products or enzymes required for essential functions of the body
like metabolism, replication, transcription, among others. This is the only form of RNA that
undergoes translation. The tRNA plays an important role in transferring amino acids from the
cytoplasm to the ribosome-mRNA complex during translation (Weissbach 2012). The rRNA is a
constituent of ribosomes. Some rRNAs have catalytic (ribozymes) and coenzyme functions.

4FUNCTIONS OF NUCLEIC ACIDS IN LIVING SYSTEMS
Reference List
Egli, M. and Saenger, W., 2013. Principles of nucleic acid structure. Springer Science &
Business Media.
Jeffrey, G.A. and Saenger, W., 2012. Hydrogen bonding in biological structures. Springer
Science & Business Media.
O’Donnell, M., Langston, L. and Stillman, B., 2013. Principles and concepts of DNA replication
in bacteria, archaea, and eukarya. Cold Spring Harbor perspectives in biology, 5(7), p.a010108.
Opentextbc.ca (2017). 9.1 The Structure of DNA | Concepts of Biology-1st Canadian Edition.
[online] Opentextbc.ca. Available at: https://opentextbc.ca/biology/chapter/9-1-the-structure-of-
dna/ [Accessed 13 Nov. 2017].
Weissbach, H. ed., 2012. Molecular mechanisms of protein biosynthesis. Elsevier.