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DNA vs RNA: 5 Key Differences

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Posted by Christine Sarikas | Apr 19, 2021 2:00:00 PM

General Education

 

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What is the difference between DNA and RNA? DNA and RNA are both types of nucleic acids, which are molecules that contain sets of instructions for cells to make genetic information and proteins. However, there are significant differences between the two of them. This guide will compare and contrast DNA and RNA in terms of structure, function, location, and more. After we give overviews of both DNA and RNA, there's a chart that allows you to easily see each key difference between DNA and RNA.

 

What Is DNA?

DNA stands for deoxyribonucleic acid. It's a macromolecule that is one of the most important components of our cells. Without DNA, cell functions like growth and reproduction wouldn't be possible.

 

DNA Structure

DNA is made up of four chemical bases: Adenine (A), Guanine (G), Cytosine (C), and Thymine (T). Human DNA consists of roughly 3 billion bases. Over 99% of those combinations are identical in humans. In DNA, A always pairs with G, and C always pairs with T. These base pairs are bonded with hydrogen bonds and are then connected to a sugar-phosphate "backbone." Put all together, they create the well-known "double helix" shape that DNA has.

 

DNA's Function

DNA stores and transfers genetic information. Think of it as your body's blueprint, containing all the instructions for development, growth, functioning, and reproduction. The massive amounts of information that DNA contains are converted into "messages" that allow cells to carry out these necessary and diverse tasks.

 

DNA's Location in Cells

Most DNA is located in the cell's nucleus. The nucleus is the control center of the cell, and it determines how the cell will function. Small amounts of DNA can also be found in the mitochondria, another organelle in cells whose function is to convert energy from food into a form that cells can use.

 

DNA Replication

DNA is self-replicating, which means that each strand of DNA acts as a template for the creation of new strands. RNA primer is used to initiate the replication process.

During replication, first the double helix "unzips," exposing the two DNA strands. (This is done by an enzyme called helicase, which breaks the hydrogen bonds between the base pairs.) After the DNA is unzipped, two strands are created, the "leading strand" and the "lagging strand." The leading strand is replicated as a continuous piece, while the lagging strand is made in smaller pieces. 

 

DNA Reactivity

As you might expect for such a critical part of the human body, DNA has multiple protections in place to make it less vulnerable to changes, either through mutation or attack. DNA is protected by proteins, contains multiple repair mechanisms, and is stable under alkaline conditions. However, DNA is more vulnerable to damage from ultraviolet light than RNA is.

 

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What Is RNA?

Like DNA, RNA is also a macromolecule made up of nucleotides. RNA plays multiple roles, including controlling gene expression, communicating cellular signals, and catalyzing biological reactions. So how is RNA different from DNA? The sections below follow the same order as the DNA sections, so you can easily compare DNA vs RNA structure, function, and more.

 

RNA Structure 

While DNA is double-stranded, forming a double helix shape, RNA is single-stranded, and its chains are significantly shorter than DNA chains (a few thousand base pairs at most, compared to millions of DNA base pairs).

RNA’s single-strand structure allows it to form complex three-dimensional shapes. The shape it forms determines whether RNA acts as mRNA, tRNA, or rRNA.

 Like DNA, RNA is made of a sugar-phosphate background with nitrogenous bases bonded by hydrogen bonds. However, while the sugar in DNA is deoxyribose, the sugar in RNA is ribose. Unlike deoxyribose, ribose has a hydroxyl group (-OH) attached to the second carbon of the sugar ring, as opposed to a hydrogen (-H).

Also like DNA, cytosine and guanine bond with each other in RNA. However, unlike DNA, RNA doesn’t contain thymine. Instead, uracil bonds with adenine. Two hydrogen bonds form between adenine and uracil, and three hydrogen bonds form between cytosine and guanine.

 

RNA's Function

If you think of DNA as the blueprint for cell processes, then RNA is the worker who puts the blueprint instructions into action. RNA converts the information that DNA contains into proteins, which can then carry out different processes. There are three main types of RNA, each with a different role:

  • Messenger RNA (mRNA): Carries codes from DNA to sites of protein synthesis on ribosomes in cell cytoplasm.

  • Transfer RNA: (tRNA): Carries amino acids to ribosomes.

  •  Ribosomal RNA: (rRNA): Combines with proteins to form ribosomes and translates information from mRNA and tRNA.

 

RNA's Location in Cells

RNA forms in the nucleolus of cells. The nucleolus is a structure within the nucleus of the cell whose purpose is to construct ribosomes (which are made of RNA and protein). After the RNA has been created, it moves to certain regions of the cell's cytoplasm depending on the type of RNA it is.



RNA Replication

Unlike DNA, RNA is not self-replicating. Instead, RNA is synthesized from DNA through the process of transcription. During transcription, a segment of DNA is copied to create an RNA molecule. RNA polymerase is the main enzyme, and it uses the DNA strands to make a complementary RNA strand.



RNA Reactivity

The hydroxyl (-OH) bonds in RNA make it more reactive than DNA. RNA is frequently broken down and reused compared to the more long-lasting DNA. RNA is also unstable at alkaline conditions, while DNA is stable. However, compared to DNA, RNA is more resistant to UV damage.

 

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DNA vs RNA: The Key Differences

What is the difference between DNA and RNA, or the ribose vs deoxyribose nucleic acids? This DNA vs RNA chart allows you to easily see each of the important ways that DNA and RNA differ from each other.         

 
DNA
RNA
Full Name
Deoxyribonucleic acid
Ribonucleic acid
Function
Replicates and stores genetic information
Carry out instructions encoded in DNA
Structure
Two strands
One strand
Sugar
Deoxyribose (which has one less hydroxyl group than ribose)
Ribose
Base Pairs
Adenine + Thymine
Guanine + Cytosine
Adenine + Uracil
Guanine + Cytosine
Pairs Bonded By
Hydrogen bonds
Hydrogen bonds
Location in Cells
Mostly nucleus, some in mitochondria
Form in nucleolus, then move to cytoplasm
Length
Several million base pairs
Several thousand base pairs
Replication
Self-replicating
Synthesized by transcription
Reactivity
Fairly stable
More reactive

 

What's Next?

Also confused with the differences between mitosis and meiosis? Our guide explains the 10 key differences between these two cell division processes.

If you want to better understand what DNA is, you need to know about nucleotides. In our guide to nucleotides, we explain what they are and how they make up DNA.

What are the most important science classes to take in high school? Check out our guide to learn all the high school classes you should be taking.

Have friends who also need help with test prep? Share this article!


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Christine Sarikas
About the Author

Christine graduated from Michigan State University with degrees in Environmental Biology and Geography and received her Master's from Duke University. In high school she scored in the 99th percentile on the SAT and was named a National Merit Finalist. She has taught English and biology in several countries.



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