Molecular Biology Cheat Sheet
The core ideas of Molecular Biology distilled into a single, scannable reference — perfect for review or quick lookup.
Quick Reference
Central Dogma of Molecular Biology
The principle describing the flow of genetic information within a biological system: DNA is transcribed into RNA, which is then translated into protein. Proposed by Francis Crick in 1958, it outlines the unidirectional transfer of sequence information, though exceptions like reverse transcription have since been discovered.
DNA Replication
The biological process by which a cell duplicates its entire DNA content before cell division, ensuring each daughter cell receives an identical copy. The process is semi-conservative, meaning each new double-stranded molecule contains one original and one newly synthesized strand.
Transcription
The process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA) by the enzyme RNA polymerase. In eukaryotes, the primary transcript undergoes processing, including 5' capping, 3' polyadenylation, and splicing of introns.
Translation
The process by which ribosomes decode mRNA to synthesize a specific polypeptide chain. Transfer RNA (tRNA) molecules carry amino acids to the ribosome, where the anticodon of each tRNA pairs with the corresponding codon on the mRNA template.
Gene Regulation
The set of mechanisms by which cells increase or decrease the production of specific gene products such as RNA and proteins. Gene regulation operates at multiple levels, including chromatin remodeling, transcriptional control via promoters and enhancers, post-transcriptional regulation, and epigenetic modifications.
CRISPR-Cas9 Gene Editing
A revolutionary genome-editing technology derived from a bacterial adaptive immune system that uses a guide RNA to direct the Cas9 nuclease to a specific DNA sequence, where it creates a double-strand break. The cell's repair mechanisms can then be harnessed to delete, insert, or replace genetic material.
Polymerase Chain Reaction (PCR)
A laboratory technique for rapidly amplifying a specific segment of DNA through repeated cycles of denaturation, annealing, and extension. Invented by Kary Mullis in 1983, PCR can produce millions of copies of a target DNA sequence from a minuscule starting sample.
Protein Folding
The physical process by which a polypeptide chain acquires its functional three-dimensional structure. The amino acid sequence determines the final conformation through a hierarchy of primary, secondary, tertiary, and quaternary structures, and misfolding can lead to diseases such as Alzheimer's and prion disorders.
Epigenetics
The study of heritable changes in gene expression that do not involve alterations to the underlying DNA sequence. Key mechanisms include DNA methylation, histone modification, and non-coding RNA regulation, which together influence how tightly DNA is packaged and whether genes are accessible for transcription.
Recombinant DNA Technology
A set of techniques for combining DNA molecules from different sources into a single molecule and introducing it into a host organism. This technology forms the basis of genetic engineering and enables the production of genetically modified organisms, therapeutic proteins, and gene therapy vectors.
Key Terms at a Glance
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