Unit 11: Genetics and Genetic engineering
Learning aim, A: understand the structure and function of nucleic acids in order to describe gene
expression and the process of protein synthesis
Assignment title: structure and function of nucleic acids
Nucleic acids:
Nucleic acids are large molecules in living cells. Their function is to contain genetic information and they
determine the characteristics of living things. Nucleic acids can be divided into two types:
1. Deoxyribonucleic acid (DNA)
2. Ribonucleic acid (RNA)
Nucleic acids are long, chain-like molecules made up of nucleotides. Which are nearly similar building
blocks. It is necessary to comprehend the structure of the nucleotides that make up nucleic acids in
order to understand the structure of nucleic acids.
Nucleotide
A nucleotide consists of 3 components that are joined together by bonds. The 3 components are:
Pentose sugar – also known as ‘5-carbon sugar’. Two of these sugars are Ribose and deoxyribose. Both
sugars have 5 carbon atoms and 1 oxygen atom. The distinction between both sugars is that ribonucleic
acid has a hydroxyl (-OH) group, whereas deoxyribonucleic acid merely has hydrogen atom. In DNA and
RNA, these sugars are different. The sugar in DNA is known as Deoxyribonucleic acid, as it contains
deoxyribose. The sugar in RNA is known as ribonucleic acid as it contains ribose.
Deoxyribonucleotides are nucleotides that include deoxyribonucleic acid. Ribonucleotides are molecules
that contain ribonucleic acid. The sugar molecule therefore decides whether a nucleotide belongs to a
DNA or RNA molecule.
Phosphate group – it is made up of four negatively charged oxygen atoms connected to a phosphorus
atom. These phosphate groups are crucial because they form phosphodiester bonds with the pentose
sugars to produce the ‘ladder’ sides of DNA.
Nitrogen base (organic base) - a nitrogen base is a molecule with nitrogen. Adenine (A) Cytosine (C) and
Guanine (G) are nitrogenous bases found in both RNA and DNA, followed by Thymine (T), which is
exclusively found in DNA, and Uracil (U), which replaces Thymine in RNA.
, Pyrimidines and purines are two different types of
nitrogenous bases. Pyrimidines include cytosine,
uracil, and thymine. That is, they have a
nitrogenous base in the form of a six-member single
ring in their molecular structure. Purines, on the
other hand, are guanine and adenine. A nitrogenous
base in the form of a nine-member double ring can
be found in these. Concisely, pyrimidines have one
ring whereas purines have two.
DNA
The hereditary substance in humans and almost all
other animals is DNA, DNA stands for
deoxyribonucleic acid. It consists of two polynucleotide chains to form a double helix. The majority of
DNA is found in the cell nucleus also known as nuclear DNA, but a tiny quantity is also present in the
mitochondria known as mitochondria DNA or mtDNA. DNA contains 4 bases such as adenine (A),
cytosine (C), guanine (G), and thymine (T). DNA is two stranded molecules, and each strand is composed
of the 4 bases, A, C, G, and T, in a double helix shape. When the 4 bases wanted to pair together it
always goes like this, C with G, A with T, and the bond between them is a hydrogen bond.
Nucleotides is what DNA is made up of, it is chemical building blocks which consists of 3 parts:
phosphate group, pentose sugar, and nitrogen bases. When these nucleotides come together as a chain,
they end up making strands, two long strands which then form double helix.
DNA function is to hold all an organism’s instructions for growth, survival, and reproduction. There is a
DNA in each cell, in eukaryotic cells, you can find DNA within the nucleus. In prokaryotic cells, you can