Principles of molecular genetics
- Benjamin A Raby, MD, MPH
Benjamin A Raby, MD, MPH
- Section Editor — Genetics
- Associate Professor of Medicine
- Harvard Medical School
The role of genetic and genomic information in the practice of clinical medicine is increasing at a rapid pace. Examples include advances in the scope of prenatal screening, including testing of maternal blood for disorders found in the fetus, diagnosis and molecular classification of rare genetic disease using next-generation sequencing, tumor classification by gene expression analysis, and pharmacogenetic applications for medication dosing. Gene identification for complex traits is also progressing rapidly. Findings from these investigations will undoubtedly translate into changes in clinical diagnostics in due time. A collection of online tutorials and instructional videos are also available at http://learn.genetics.utah.edu.
Physicians involved in the care of patients will require knowledge of the basic principles of genetics to adequately incorporate these applications into clinical practice. The basic principles of molecular genetics are reviewed here. The material summarized here is essential to understand topics related to the basic science and clinical applications of genetics addressed elsewhere within UpToDate. Readers are encouraged to consult introductory texts in molecular genetics and biology for more detailed reviews of these concepts. Examples of suitable texts are provided in the reference section [1,2].
A glossary of genetic terms is available separately. (See "Genetics: Glossary of terms".)
PRINCIPLES OF MOLECULAR BIOLOGY
The fundamental processes by which heritable information is stored, transmitted from generation to generation, and translated from genetic code to function in living organisms are common to all eukaryotes. These processes were termed the “Central Dogma of Molecular Biology” by Francis Crick in 1958 (figure 1), although the use of the word “Dogma” has been debated subsequently.
Heritable genetic information is stored as long stretches of deoxyribonucleic acid (DNA), a stable molecule that is replicated and transmitted from one generation to the next. Segments of DNA can encode functional elements called genes that are transcribed into messenger ribonucleic acid (messenger RNA or mRNA). mRNA then serves as the template for protein synthesis in a process called translation.
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- PRINCIPLES OF MOLECULAR BIOLOGY
- Nucleic acids
- The double helix and template-directed nucleic acid synthesis
- Mitosis and DNA replication
- Meiosis and sustained genetic diversity
- RNA transcription
- Post-transcription modification of mRNA
- - Splicing
- - Capping
- - Polyadenylation
- Post-translational modification
- IMPLICATIONS FOR MEDICINE