Time-saving video on the circulatory system. The circulatory system transports nutrients and blood cells to and from cells throughout the body. The circulatory systems includes veins, arteries and capillaries.
Ribosomal RNA (rRNA) is found in the cell's ribosomes, the specialized structures that are the sites of protein synthesis). Transfer RNA (tRNA) found in the cytoplasm which carries amino acids to the ribosomes for incorporation into a protein.
The nucleotide uridine is never found in DNA and thymine is almost exclusively found in DNA. Thymine is found in tRNAs but not rRNAs nor mRNAs. There are several less common bases found in DNA and RNA. The primary modified base in DNA is 5-methylcytosine. A variety of modified bases appear in the tRNAs.