Nucleic Acid - Definition, Function & Examples | biology dictionary (2023)


A nucleic acid is a chain of nucleotides that stores genetic information in biological systems. It creates DNA and RNA, which store the information cells need to make proteins. This information is stored in multiple sets of three nucleotides known as codons.

How do nucleic acids work?

The name comes from the fact that these molecules are acids - that is, they are good at donating protons and accepting pairs of electrons in chemical reactions - and the fact that they were first discovered in the nucleus of our cells.

Typically,A nucleic acid is a large molecule made up of a chain, or "polymer", of units called "nucleotides.”All life on Earth uses nucleic acids as a means of recording hereditary information, that is, nucleic acids are the hard disks that contain the essential blueprint or "source code" for making cells.

For many years, scientists have wondered how living things "knew" how to make all the complex materials they need to grow and survive, and how they passed on their traits to their offspring.

Scientists have finally found the answer in the form ofADN– deoxyribonucleic acid – molecule located in the nucleus of cells, which was passed from mother cells to “daughter” cells.

When DNA was damaged or transmitted incorrectly, scientists found that cells did not function properly. DNA damage would cause cells and organisms to develop incorrectly, or become so damaged that they simply die.

Later experiments revealed that another type of nucleic acid, RNA or ribonucleic acid, acted as a "delivery courier” which could contain copies of the instructions found in the DNA. Ribonucleic acid has also been used to pass instructions from generation to generation by some viruses.

(Video) What are Nucleic Acids? Nucleic Acid Structure & Function

Function of nucleic acids

Nucleic acids store information like computer code.

By far the most important function of nucleic acids for living things is their role as information carriers.

Because nucleic acids can be created with four "bases" and because "base pairing rules" allow information to be "copied" using one strand of nucleic acids as a template to create another,these molecules can hold and copy information.

To understand this process, it can be helpful to compare the DNA code with the binary code used by computers. The two codes are very different in their details, but the principle is the same. Just as your computer can create entire virtual realities simply by reading sequences of 1's and 0's, cells can create entire living organisms by reading sequences of all four base pairs of DNA.

As you can imagine, without binary code, you would have no computers and no computer programs. Likewise, living organisms need intact copies of their DNA "source code" to function.

The parallels between the genetic code and the binary code have led some scientists to propose the creation of "genetic computers" that could store information much more efficiently than silicon-based hard drives. However, as our ability to record information about silicon has advanced, little attention has been paid to researching "genetic computers".

information protection

Since the source code of DNA is as vital to a cell as its operating system is to your computer, DNA must be protected from damage. To carry the DNA's instructions to other parts of the cell, copies of its information are made using another type of nucleic acid: RNA.

It is these RNA copies of the genetic information that are sent out of the nucleus and around the cell to be used as instructions by the cellular machinery.

Cells also use nucleic acids for other purposes.ribosomes– the cellular machines that make proteins – and some enzymes are made of RNA.

(Video) Nucleic acids - DNA and RNA structure

DNA uses RNA as a kind of protective mechanism, separating DNA from the chaotic environment of the cytoplasm. Inside the nucleus, the DNA is protected. Outside the nucleus, movements of organelles, vesicles and other cellular components can easily damage the long, complex strands of DNA.

The fact that RNA can act both as a hereditary material and as an enzyme reinforces the idea that the beginning of life could have been a self-replicating, self-catalyzing RNA molecule.

Examples of Nucleic Acids

The most common nucleic acids in nature are DNA and RNA. These molecules form the basis of most life on Earth and store the information needed to create proteins that, in turn, complete the functions necessary for cells to survive and reproduce. However, DNA and RNA are not the only nucleic acids. However, artificial nucleic acids have also been created. These molecules function in the same way as natural nucleic acids, but they can perform a similar function. In fact, scientists are using these molecules to build the foundation of an "artificial life form" that could maintain artificial nucleic acid and extract information from it to build new proteins and survive.

Generally speaking, the nucleic acids themselves differ in each organism based on the sequence of nucleotides within the nucleic acid.This sequence is “read” by the cellular machinery to link amino acids in the correct sequence, forming complex protein molecules with specific functions.

Nucleic acids and genetics

the genetic code

Today, scientists know that the source code of cells is literally written in nucleic acids.genetic engineeringit alters the characteristics of organisms by adding, removing, or rewriting parts of their DNA, and subsequently changing the "parts" that cells produce.

A sufficiently skilled genetic "programmer" can create the instructions for a living cell from scratch using the nucleic acid code. Scientists did just that in 2010, using an artificial DNA synthesizer to "write" a genome from scratch, using snippets of source code extracted from other cells.

All living cells on Earth "read" and "write" their source codes in almost exactly the same "language" using nucleic acids.Sets of three nucleotides, called codons, can code for any amino acid, either for the ending orprotein startProduction.

Other properties of nucleic acids can influence DNA expression in more subtle ways, for example by binding and making it difficult for transcription enzymes to access the code they store.

(Video) Nucleic Acids

The fact that all living cells on Earth "speak" almost the same genetic "language" supports the idea of ​​a universal common ancestor, that is, the idea that all life on Earth today began with a single primordial cell, whose descendants evolved to give rise to all modern living species.

From a chemical point of view,The nucleotides that come together to create nucleic acids consist of a five-carbon sugar, aPhosphate groupand a nitrogen-containing base.The following image shows structural drawings of the four nitrogen bases in DNA and the four in RNA used by living things on Earth in their nucleic acids.

It also shows how the sugar-phosphate "structures" stick together at an angle that creates a helix, or a double helix in the case of DNA, when several nucleic acids are joined together into a single molecule:

Nucleic acids are polymers of nucleotides.

DNA and RNA are polymers made of single nucleotides. The term "polymer" comes from "poly" for "many" and "mer" for parts, referring to the fact that each nucleic acid is composed of many nucleotides.

Because nucleic acids can be naturally produced by the reaction of inorganic ingredients with each other, and because they are possibly the most essential ingredient for life on Earth, some scientists believe thatthe first "life" on Earth may have been a self-replicating sequence of amino acidsit was created by natural chemical reactions.

Nucleic acids have been found in meteorites from space, showing that these complex molecules can form by natural causes even in environments where there is no life.

Some scientists have even suggested that such meteorites may have helped create the first self-replicating nucleic acid "life" on Earth. This seems possible, but there is no firm evidence to say whether it is true.

nucleic acid structure

Since nucleic acids can form huge polymers that can take many forms, there are several ways to analyze "nucleic acid structure". It can mean something as simple as the sequence of nucleotides in a piece of DNA, or something as complex as how the DNA molecule folds and how it interacts with other molecules. Nucleic acids are mainly formed with the elements carbon, oxygen, hydrogen, nitrogen and phosphorus.

(Video) What is DNA and How Does it Work?

check out ournucleic acid structurearticle for more information.

nucleic acid monomer

nucleotidesThey are the individual monomers of a nucleic acid. These molecules are quite complex and consist of a nitrogenous base plus a sugar-phosphate “backbone”.Fullfour basic types of nucleotides, adenine (A), guanine (G), cytosine (C) and thymine (T).

When our cells join nucleotides together to form polymers called nucleic acids, they join by replacing the oxygen molecule of the 3' sugar of one nucleotide backbone with the oxygen molecule of the 5' sugar of another nucleotide.

This is possible because the chemical properties of nucleotides allow the 5' carbons to be attached to multiple phosphates. These phosphates are attractive binding partners for the 3' oxygen molecule to the 3' oxygen of the other nucleotide, so the oxygen molecule immediately jumps to bind the phosphates and is replaced by the 5' sugar oxygen. The two nucleotide monomers are then fully joined by a covalent bond through this oxygen molecule, making them a single molecule.

Nucleotides are the monomers of nucleic acids, but just as nucleic acids can serve purposes other than carrying information, so can nucleotides.

The life energy transport molecules ATP and GTP are made of nucleotides: the "A" and "G" nucleotides, as you might have guessed.

In addition to transporting energy, GTP also plays a vital role in cellular G protein signaling pathways. The term "G protein" actually comes from the "G" in "GTP", the same G found in the genetic code.

G proteins are a special type of protein that can cause signaling cascades with important and complex consequences within a cell. When GTP is phosphorylated, these G proteins can be turned on or off.

(Video) Nucleic Acids



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