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.
RNA (ribonucleic acid) molecules differ from DNA molecules in several ways. RNA molecules are single-stranded, and their nucleotides contain ribose rather than deoxyribose sugar. Like DNA, RNA nucleotides each contain one of four organic bases, but whereas adenine, cytosine, and guanine nucleotides occur in both DNA and RNA, thymine nucleotides are found only in DNA. In place of thymine nucleotides, RNA molecules contain uracil nucleotides. The first step in the delivery of information from the nucleus to the cytoplasm is the synthesis of a type of RNA called messenger RNA (mRNA). In messenger RNA synthesis, RNA nucleotides form complementary base pairs with a section of a strand of DNA that encodes a particular protein.