DNA vs RNA: The Differences in One Table
DNA and RNA are both nucleic acids made of nucleotides, but DNA has deoxyribose sugar, the base thymine and two strands in a double helix, while RNA has ribose sugar, the base uracil and usually one strand. DNA stores genetic information; RNA carries it out by helping to make proteins.
DNA is made of repeating units called nucleotides
DNA, like RNA, is a polymer. DNA is made of repeating units called nucleotides, and each nucleotide has three parts:
- A phosphate group.
- A five-carbon sugar.
- A nitrogen-containing base.
In DNA the sugar is deoxyribose and the bases are adenine (A), thymine (T), guanine (G) and cytosine (C). Nucleotides join through their sugar and phosphate groups to make a long backbone, with the bases pointing inwards. In RNA the sugar is ribose and thymine is replaced by uracil.
DNA vs RNA: comparison table
| Feature | DNA | RNA |
|---|---|---|
| Full name | Deoxyribonucleic acid | Ribonucleic acid |
| Sugar | Deoxyribose | Ribose (one extra oxygen atom) |
| Bases | A, T, G, C | A, U, G, C |
| Strands | Two, in a double helix | Usually one |
| Length | Very long (human genome about 3.2 billion base pairs) | Short, from tens to a few thousand bases |
| Location | Nucleus (plus mitochondria and chloroplasts) | Made in the nucleus, works mainly in the cytoplasm |
| Main job | Long-term storage of genetic information | Copies and carries out the instructions |
| Stability | Very stable | Less stable, broken down quickly |
What are the three major differences between DNA and RNA?
If you need a quick exam answer, give these three:
- Sugar: DNA has deoxyribose, RNA has ribose.
- Base: DNA has thymine, RNA has uracil in its place.
- Structure: DNA is double-stranded, RNA is usually single-stranded.
Why does RNA use uracil?
Both bases pair with adenine, so the difference is mainly chemical. Uracil costs the cell less energy to make than thymine. DNA uses thymine because it makes copying errors easier to detect and fix, which protects the long-term code. RNA is short-lived, so the cheaper base works fine.
What are the three types of RNA?
The three types of RNA each play a different part in making proteins:
- mRNA (messenger RNA): a working copy of a gene that carries the code from the nucleus to a ribosome.
- tRNA (transfer RNA): brings the correct amino acid to the ribosome, matching its anticodon to each mRNA codon.
- rRNA (ribosomal RNA): forms the structure of the ribosome and helps join amino acids together.
You can follow all three at work in how DNA makes a protein.
Base pairing: worked example
Base pairing follows fixed rules, and the only change in RNA is U instead of T.
- DNA to DNA: A pairs with T, and C pairs with G.
- DNA to RNA: A pairs with U, T pairs with A, C pairs with G and G pairs with C.
Take the DNA template strand TACGGT:
- Its complementary DNA strand would be ATGCCA.
- The mRNA copied from it is AUGCCA: each A on the template is matched by U.
- The ribosome reads AUG as the start codon (methionine), then CCA as proline.
If you know DNA's base-pairing, you can convert any sequence in seconds.
Where are DNA and RNA found in the cell?
In human cells, nearly all DNA is in the nucleus, packed into 46 chromosomes, with a small circular amount in the mitochondria. RNA is made in the nucleus and most of it works in the cytoplasm, especially at the ribosomes. Some viruses, such as influenza, use RNA instead of DNA as their genetic material.
Common mistakes
- Writing T in RNA. RNA never contains thymine.
- Saying RNA has no double-stranded regions. It is usually single-stranded but can fold back and pair with itself, as tRNA does.
- Confusing "deoxy" and "oxy": deoxyribose has one fewer oxygen atom than ribose.
- Saying DNA makes proteins directly. It is copied into mRNA first.
Frequently asked questions
What is the main difference between DNA and RNA?
The main difference is their job and structure. DNA is a stable double helix that stores the genetic code for the long term. RNA is a mostly single-stranded, shorter molecule that copies the code and helps build proteins.
DNA is made of repeating units called what?
DNA is made of repeating units called nucleotides. Each nucleotide is a phosphate group, a deoxyribose sugar and one base (A, T, G or C). Thousands to millions of nucleotides join into a strand.
Which is more stable, DNA or RNA?
DNA is far more stable. Its deoxyribose sugar and double-stranded structure resist damage, so it can store information for a lifetime. RNA is usually broken down within minutes to hours, which suits its temporary role.
How many types of RNA are there?
There are three main types involved in making proteins: mRNA, tRNA and rRNA. Cells also make other RNAs, such as regulatory RNAs, but these three are the ones most courses ask about.
Try it yourself
Open the DNA Builder, build a short DNA strand and note which base pairs with each letter. Then copy it into mRNA by swapping T for U, and compare your result with the mRNA the tool makes.
See it for yourself, in 3D and free.
Try it in the DNA Builder