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The name "satellite DNA" refers to the phenomenon that repetitions of a short DNA sequence tend to produce a different frequency of the bases adenine, cytosine, guanine, and thymine, and thus have a different density from bulk DNA such that they form a second or "satellite" band(s) when genomic DNA is separated along a cesium chloride density ...
A non-coding RNA (ncRNA) is a functional RNA molecule that is not translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally important types of non-coding RNAs include transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs), as well as small RNAs such as ...
De novo gene birth is the process by which new genes evolve from non-coding DNA. [ 1 ] [ 3 ] De novo genes represent a subset of novel genes, and may be protein-coding or instead act as RNA genes. [ 4 ]
This also removes the need for an RNA primer to initiate RNA synthesis, as is the case in DNA replication. The non-template (sense) strand of DNA is called the coding strand, because its sequence is the same as the newly created RNA transcript (except for the substitution of uracil for thymine). This is the strand that is used by convention ...
DNA sequences that carry the instructions to make proteins are referred to as coding sequences. The proportion of the genome occupied by coding sequences varies widely. A larger genome does not necessarily contain more genes, and the proportion of non-repetitive DNA decreases along with increasing genome size in complex eukaryotes. [31]
The common theme is that the original proponents of junk DNA thought that all non-coding DNA was junk. [2] [6] This claim has been attributed to a paper by David Comings in 1972 [28] where he is reported to have said that junk DNA refers to all non-coding DNA. [19] But Comings never said that.
Long non-coding RNA/lncRNA: Non-coding RNA transcripts that are more than 200 nucleotides long. Members of this group comprise the largest fraction of the non-coding transcriptome other than introns. It is not known how many of these transcripts are functional and how many are junk RNA. transfer RNA/tRNA; micro RNA/miRNA: 19-24 nucleotides (nt ...
The non-intron sequences that become joined by this RNA processing to form the mature RNA are called exons. [3] Introns are found in the genes of most eukaryotes and many eukaryotic viruses, and they can be located in both protein-coding genes and genes that function as RNA (noncoding genes). There are four main types of introns: tRNA introns ...