DNA vs. RNA — Differences & Similarities

DNA vs RNA

Functions:

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are very similar molecules that serve very different functions. DNA is responsible for long term storage of the genetic code. It resides in the nucleus of eukaryotic cells. RNA, on the other hand, is responsible for several important processes including transporting the genetic information found in DNA to other sites in the cell where it can be used to make proteins. It is found in the cytoplasm of a cell.

Structures:

Despite their different jobs, DNA and RNA have almost the same basic structure. Each one is made up of nucleotides. These tiny subunits are made of a sugar, nitrogen base, and phosphate group.

The differences start to show up when we take a closer look at their structures.

The most obvious difference is that DNA is a double-stranded molecule, while RNA is single-stranded. DNA is also much longer than RNA. An entire chromosome is actually just one molecule of DNA.

While both DNA and RNA have sugar molecules in their subunits, those sugars are slightly different. DNA uses deoxyribose, but RNA uses ribose, which has an extra hydroxyl group $(OH^{-})$ tacked on.

DNA and RNA also have nearly identical nitrogenous bases. Both have the bases adenine, cytosine, and guanine. However, DNA uses a fourth base called thymine. RNA's fourth base is uracil. The only difference here is that uracil is missing a methyl group $(CH_{3})$.

What Are the Differences Between DNA and RNA?

Need to remember what makes DNA different from RNA? This Venn diagram can help remind you.

DNA and RNA are very similar on a fundamental level. They belong to the same group of molecules and have the same basic parts. However, they do have some important chemical differences that lead to very distinct functions in the cell.

Structure of DNA

DNA is a macromolecule made up of two antiparallel strands of bonded deoxyribonucleotides. A deoxyribonucleotide consists of a phosphate group, 5-carbon deoxyribose sugar, and one of DNA's four nitrogenous bases: thymine, cytosine, guanine, or adenine.

When looking at DNA, you can see that it looks kind of like a spiral staircase. This structure is called a "double helix". It occurs when the bases in two strands bond to each other in opposite directions. The complementary base pairs in DNA require that adenine pairs with thymine (or A pairs with T) and guanine pairs with cytosine (or G pairs with C).

Structure of RNA

RNA is a single-stranded molecule that consists of bonded ribonucleotides. Similar to the nucleotides found in DNA, ribonucleotides consist of a phosphate group, a 5-carbon ribose sugar and one of RNA's four nitrogenous bases: uracil, cytosine, guanine, or adenine.

Function

The primary function of DNA is to provide genetic information for living organisms. This genetic material codes for different amino acids that get strung together to make proteins. DNA is passed down from the parent organisms to their offspring.

RNA mainly helps in the expression of the genes that DNA encodes by allowing the DNA to be interpreted and code for various proteins. Its main purpose involves the transcription and translation of DNA into the proteins necessary for survival.

The three main types are rRNA, mRNA, and tRNA. Their function depends on the specific type of RNA.

$$\color{#8925AE}{\text{Vocabulary Review:}}$$

$\color{#8925AE}{\text{Monomer}}$ : Any molecule that can react with other molecules of the same or different makeup to form a chain, or polymer

$\color{#8925AE}{\text{Polymer}}$ : A chain of monomers made of a specific type of compound

$\color{#8925AE}{\text{Macromolecule}}$ : A polymer that has a large (macro) molecular mass. There are four main types in organisms: carbohydrates, proteins, lipids, and nucleic acids

$\color{#8925AE}{\text{Nucleotides}}$ : The monomers of nucleic acids. Made up of a nitrogen group, a phosphorus group, and a 5-carbon ring

$\color{#8925AE}{\text{Nucleic Acid}}$ : Complex polymer that stores information in a cell in the form of a code. DNA and RNA

DNA vs. RNA

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are both types of nucleic acids. It's even part of their names. There aren't words to describe how complex and how beautiful these molecules are.

You're probably more familiar with DNA and can recognize its famous double helix shape. RNA looks like half of DNA. It is single-stranded.

The two molecules are very similar in many ways. Both DNA and RNA are made of nucleotides and have the same basic structure. Each one contains a 5-carbon sugar, phosphate group, and nucleobases (nitrogenous bases).

Once we take a closer look, we can find many very important differences between the two molecules.

DNA has the 5-carbon sugar deoxyribose and RNA has the 5-carbon sugar ribose, hence their names.

Nucleobases

While the phosphate groups are identical, DNA and RNA have different nucleobases. Well, partially different. Both nucleic acids have the bases cytosine, guanine, and adenine. However, DNA has the additional nucleobase thymine, while RNA has the nucleobase uracil.

The nucleobases in DNA and RNA have preferred partners to hydrogen bond with:

In both DNA and RNA, cytosine pairs with guanine. In DNA adenine will pair with thymine, while in RNA adenine will pair with uracil.

So, the three main structural differences between RNA and DNA are as follows:

• RNA is single-stranded while DNA is double-stranded.
• RNA contains uracil while DNA contains thymine.
• RNA has the sugar ribose while DNA has the sugar deoxyribose.

Functions

Finally, both DNA and RNA serve kinda similar functions, but not quite. DNA is like an encyclopedia of all the genetic information for a cell. It contains everything there is to know about a person. RNA is like a photocopy of a single topic. Essentially, it copies just some of the information found in DNA, and carries it whenever it's needed by the cell. RNA can be thought of like a copy of a segment of DNA that you can throw away once it's not needed anymore. Sometimes it is even a copy of one specific gene. Neat, huh?

$$\color{#8925AE}{\text{Vocabulary Review:}}$$

$\color{#8925AE}{\text{Monomer}}$ : Any molecule that can react with other molecules of the same or different makeup to form a chain, or polymer

$\color{#8925AE}{\text{Polymer}}$ : A chain of monomers made of a specific type of compound

$\color{#8925AE}{\text{Macromolecule}}$ : A polymer that has a large (macro) molecular mass. There are four main types in organisms: carbohydrates, proteins, lipids, and nucleic acids

$\color{#8925AE}{\text{Nucleotides}}$ : The monomers of nucleic acids. Made up of a nitrogen group, a phosphorus group, and a 5-carbon ring

$\color{#8925AE}{\text{Nucleic Acid}}$ : Complex polymer that stores information in a cell in the form of a code. DNA and RNA

(Video) DNA Versus RNA

by Teacher's Pet

This video by Teacher's Pet covers the differences and similarities between DNA and RNA.

$\underline{\text{Summary}}$

Both DNA and RNA:

• Are types of nucleic acids

• Have the bases Adenine, Guanine, and Cytosine

DNA:

• Contains the sugar deoxyribose

• Double-stranded

• Has the base Thymine

• Very long

RNA:

• Contains the sugar ribose

• Single-stranded

• Has the base Uracil

• Much shorter

• Has three types (mRNA, tRNA, rRNA)