MCAT Content / Genetic Code / Messenger Rna Mrna

Messenger RNA (mRNA)

Topic: Genetic Code

Messenger RNA or mRNA is a type of RNA that is formed by transcription of DNA and encodes a protein.

During transcription, a DNA sequence is copied into a complementary RNA molecule. In eukaryotes, this occurs in the nucleus. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that enzymes can convert back and forth from DNA to RNA. Unlike DNA replication, transcription results in a RNA complement that substitutes the RNA uracil (U) in all instances where the DNA thymine (T) would have occurred. You can see this represented in the figure below:

The RNA molecule that is copied from a DNA sequence is called a transcript. Some transcripts are used as structural or regulatory RNAs, and others encode one or more proteins. If the transcribed gene encodes a protein, the result of transcription is messenger RNA (mRNA), which will then move to ribosomes in the cytoplasm and be used to create a protein in the process of translation.

Practice Questions

Khan Academy

Molecular genetics and microbiology of Zaire Ebolavirus

MCAT Official Prep (AAMC)

Online Flashcards Biology Question 25

Key Points

• Messenger RNA or mRNA is formed from a DNA sequence in a process known as transcription.

• mRNA is complementary to the template strand of DNA it is copied from, except the RNA-specific nucleotide uracil replaces thymine. The mRNA sequence is exactly the same as the non-template strand of DNA

• mRNA is used by ribosomes in the cytoplasm to synthesize a polypeptide chain (protein).

Key Terms

Messenger RNA (mRNA): An RNA molecule that is copied from a DNA sequence during transcription and is used to create a protein during translation.

Transcription: The process of converting a specific sequence of DNA into a new RNA molecule.

Complementary: Describes the pairing between specific nucleotides in DNA and RNA.

Uracil (U): A nucleotide specifically found in RNA that replaces the thymine found in DNA.

Transcript: A RNA molecule that is copied from a DNA sequence during transcription.

Ribosome: A macromolecule composed of RNA and proteins, located in the cytoplasm or on the rough endoplasmic reticulum, that uses an mRNA sequence to produce a polypeptide chain during translation.

Translation: The process where RNA is used to create a new polypeptide chain (protein).

Billing Information
We had trouble validating your card. It's possible your card provider is preventing us from charging the card. Please contact your card provider or customer support.
{{ cardForm.errors.get('number') }}
{{ registerForm.errors.get('zip') }}
{{ registerForm.errors.get('coupon') }}
Tax: {{ taxAmount(selectedPlan) | currency spark.currencySymbol }}

Total Price Including Tax: {{ priceWithTax(selectedPlan) | currency spark.currencySymbol }} / {{ selectedPlan.interval | capitalize }}