Central Dogma & Genetic Medicine

Scale: 5 nm

Genes are sequences of DNA that, for the most part, code for proteins. The flow of genetic information from DNA to RNA to protein has been referred to as the central dogma of molecular biology.

Mutations in genes can affect the resulting proteins and some mutations cause disease. To treat genetic diseases, scientists and doctors can intervene at different steps in the central dogma.

Scroll down to explore the steps in the central dogma pathway in a human cell. Select the plus signs to explore a genetic medicine strategy that is being used to intervene at a particular step and a disease that could be treated using that strategy.

Cell

Most cells in our bodies contain DNA inside the nucleus.

This image is a round semi-translucent shape labeled cytoplasm, with a cut-away in the front revealing internal cell structures of varying shapes, including a central round structure labeled nucleus. There is a cut-away in the front of the nucleus revealing an internal nested and coiled spaghetti-like chain labeled D N A.

DNA

The DNA in the nucleus of a cell is referred to as its genome. The human genome contains about 20,000 genes.

This image depicts the nested coiled strands of D N A in the shape of a twisted ladder called a double helix, which is made of strands of nucleotide bases held together with hydrogen bonds.

RNA Transcription

An enzyme called RNA polymerase transcribes a gene's DNA into an RNA transcript with a complementary sequence.

This is an animation of the enzyme called R N A polymerase, depicted as an irregular round shape, sliding along the strands of D N A. After the R N A polymerase comes to a stop on a segment of D N A, a simple depiction of a strand of an R N A transcript extends from the enzyme with color coded segments labeled Exon and Intron.

RNA Splicing

The RNA transcript is edited through splicing. A protein complex called the spliceosome trims out introns and splices together exons to produce a mature messenger RNA (mRNA).

This image depicts the large protein complex called spliceosome, in the shape of an irregular pyramid, sitting in the middle of the Exon R N A segment. The intron segment is shown as a loop separated from and next to the Exon segment.

mRNA Transport

The mRNA is transported from the nucleus to the cytoplasm of the cell.

This image is a simple representation of a strand of m-R N A without the associated proteins, formed from the sliced together exons segments from the R N A transcript.

Translation

The ribosome, a complex of proteins and ribosomal RNAs, translates the mRNA code into amino acids. Each amino acid is brought to the ribosome by a special kind of RNA called transfer RNA (tRNA) and added to a growing polypeptide chain.

This animation depicts round-like shapes of the protein R N A complex called ribosome wrapped around and bound to the m-R N A strand. A chain of amino acids called a polypeptide extends from the ribosome. Molecules of transfer R N A are positioned to the right of the m-R N A strand and move left across the strand, carrying and transferring the appropriate amino acid to the ribosome for it to be added to the attached polypeptide chain, resulting in growth of the chain.

Protein Processing

The complete polypeptide chain is folded and assembled into a 3-dimensional functional protein, a process that entails many steps and additional proteins. Processing can take place in the cytoplasm or in the endoplasmic reticulum and Golgi system.

This image is of a folded chain of amino acids called a polypeptide, which is processed to become a mature protein molecule.