DNAStrukturs

DNAStrukturs refers to the diverse shapes DNA molecules can take beyond the simple canonical double helix. The most familiar form is the B-DNA double helix, a right-handed structure in which two antiparallel sugar-phosphate backbones enclose a core of base pairs A–T and C–G. Base stacking and hydrogen bonding confer stability; the helix contains major and minor grooves that provide access for proteins involved in replication, transcription and repair.

Besides B-DNA, other forms arise under different conditions. A-DNA is also right-handed but more compact and occurs in dehydrated samples and RNA–DNA hybrids. Z-DNA is left-handed, with a zigzag backbone, favored by alternating purine–pyrimidine sequences and high supercoiling; it is associated with regulatory processes and genomic instability.

DNA can form noncanonical structures that play regulatory roles. Hairpins and cruciforms arise from inverted repeats; G-quadruplexes are four-stranded structures formed by guanine-rich runs; i-motifs are cytosine-rich structures at acidic pH; triplex or H-DNA structures involve Hoogsteen base pairing and can affect transcription.

Within cells, DNA is organized with proteins into higher-order structures. DNA wraps around histone proteins to form nucleosomes, which further fold into chromatin fibers and higher-order structures, enabling compact packaging and regulation of gene expression. Chromosome architecture influences replication timing and genome stability.

Understanding DNA structures aids fields from molecular biology to biotechnology. In addition to natural structure-function relationships, engineered DNA nanostructures use designed sequences to fold into predefined shapes for research, medicine, and materials science.