See pre-embryo . Short preexisting polynucleotide chain to which new deoxyribonucleotides can be added by DNA polymerase. Single-stranded DNA or RNA molecules of specific base sequence, labeled either radioactively or immunologically, that are used to detect the complementary base sequence by hybridization. A complementary target for a probe strand. Bacteria are prokaryotes.
Promoters are critically involved in the regulation of gene expression .
The sequence of amino acids in a protein is determined by the sequence of nucleotides in a DNA molecule. As the chain of amino acids is being synthesized, it is also folded into higher order structures shaped, for example, like helices or like flat sheets. Proteins are required for the structure, function, and regulation of cells , tissues, and organs in the body. This protein could be identical to a protein made by the body, or it could be a protein designed in the lab to mimic a naturally occurring protein. The purines in DNA and RNA are adenine and guanine.