Search results
Results from the WOW.Com Content Network
Life functions through the specialized chemistry of carbon and water, and builds largely upon four key families of chemicals: lipids for cell membranes, carbohydrates such as sugars, amino acids for protein metabolism, and nucleic acid DNA and RNA for the mechanisms of heredity. Any successful theory of abiogenesis must explain the origins and ...
It is this linear sequence of nucleotides that make up the primary structure of DNA or RNA. Nucleotides consist of 3 components: Nitrogenous base. Adenine; Guanine; Cytosine; Thymine (present in DNA only) Uracil (present in RNA only) 5-carbon sugar which is called deoxyribose (found in DNA) and ribose (found in RNA). One or more phosphate ...
In the 1980s, RNA structures capable of self-processing were discovered, [26] with the RNA moiety of RNase P acting as its catalytic subunit. [27] These catalytic RNAs were referred to as RNA enzymes, or ribozymes, are found in today's DNA-based life and could be examples of living fossils. Ribozymes play vital roles, such as that of the ribosome.
The integrity of the DNA was maintained by a group of repair enzymes including DNA topoisomerase. [16] If the genetic code was based on dual-stranded DNA, it was expressed by copying the information to single-stranded RNA. The RNA was produced by a DNA-dependent RNA polymerase using nucleotides similar to those of DNA. [10]
It has become widely accepted in science [1] that early in the history of life on Earth, prior to the evolution of DNA and possibly of protein-based enzymes as well, an "RNA world" existed in which RNA served as both living organisms' storage method for genetic information—a role fulfilled today by DNA, except in the case of RNA viruses—and ...
HuD (also called ELAVL4) binds to AREs and increases the half-life of ARE-bearing mRNAs in neurons during brain development and plasticity. [ 8 ] AREsite —a database for ARE containing genes—has recently been developed with the aim to provide detailed bioinformatic characterization of AU-rich elements.
RNA is subdivided into many categories, including messenger RNA (), ribosomal RNA (), transfer RNA (), long non-coding RNA (), and several other small functional RNAs.. Whereas many proteins have quaternary structure, the majority of RNA molecules have only primary through tertiary structure and function as individual molecules rather than as multi-subunit structures
Modern evidence suggests that early cellular evolution occurred in a biological realm radically distinct from modern biology. It is thought that in this ancient realm, the current genetic role of DNA was largely filled by RNA, and catalysis was also largely mediated by RNA (that is, by ribozyme counterparts of enzymes).