Genetic Gallery

HIV reverse transcription enzyme

HIV reverse transcription enzyme. Molecular models of the reverse transcriptase enzyme found in HIV (the human immunodeficiency virus). The foreground model shows the helices and arrowed sheets representing the enzyme's shape (secondary structure). The background model shows the 7844 atoms (spheres) of the molecular structure. Reverse transcriptase is an enzyme that is a key part of the process of producing DNA (deoxyribonucleic acid) from the instructions contained in a strand of RNA (ribonucleic acid). Many viruses, including HIV, consist of a core of RNA, and this reverse transcription is how HIV infects human cells. This enzyme is from the HIV-1 form of HIV, the virus that causes AIDS (acquired immune deficiency syndrome)

© LAGUNA DESIGN/SCIENCE PHOTO LIBRARY

Computer artwork of DNA replication

DNA replication. Computer artwork depicting DNA (deoxyribonucleic acid) replication. This segment of DNA is being "unzipped" to form a Y-shaped replication fork. During replication, the two spiral strands of DNA (red) unwind. Next, the bonds between the bases (pink, green, yellow & blue) that form the DNA's genetic code are broken by the enzyme DNA polymerase (zip at centre left). Daughter strands (blue) are built along each strand of parental DNA using the original base sequence as a template for the new matching DNA strands. Finally the enzyme DNA ligase (zips at upper and lower right) "zips" the strands together to form two identical molecules of DNA

© LAGUNA DESIGN/SCIENCE PHOTO LIBRARY

Grapevine genome sequencing

Grapevine genome sequencing. Data from a gelelectrophoresis experiment to sequence the PinotNoir grape ( Vitis sp. ) genome. This technique isused to separate, in sequence, nucleotide basesfrom DNA (deoxyribonucleic acid) fragments. DNAcontains 4 bases (adenine, cytosine, guanine andthymine), which are represented here by differentcolours. The DNA fragments are placed in a porousgel that has an electric current applied to it.The nucleotides move down the gel according totheir size. After the process has run the basesappear as bands on the gel. The sequences of basesmake up genes, which encode an organism's geneticinformation. Photographed at the AgriculturalInstitute of San Michelle all'Adige, Trento, Italy

© Mauro Fermariello/Science Photo Library