üheahelalisteks

Üheahelalisteks is an Estonian term that translates to "single-stranded" in English. It is primarily used in the context of nucleic acids, specifically DNA and RNA. In molecular biology, a single-stranded nucleic acid is one that consists of a single polynucleotide chain, as opposed to a double-stranded molecule where two such chains are complementary and coiled around each other.

Single-stranded DNA (ssDNA) and single-stranded RNA (ssRNA) play crucial roles in various biological processes. For instance, ssDNA can be found in certain viruses and is an intermediate in DNA replication and repair mechanisms. ssRNA is the genetic material of many viruses, such as retroviruses, and is also a fundamental component in gene expression. Messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA) are all forms of ssRNA that are vital for protein synthesis.

The structure of a single strand allows it to fold upon itself, forming complex three-dimensional shapes through base pairing between complementary regions within the same strand. This folding is critical for the function of many RNA molecules, enabling them to act as enzymes (ribozymes) or structural components of cellular machinery. The ability of single strands to hybridize with complementary strands is also the basis for many molecular biology techniques, such as PCR and Northern blotting.