What on the rungs of the ladder of dna is is composed of

What are two ways in which waves erode the land?

Part of the elbow is formed by the end of the humerus. what do you call this part?

Accuracy in the translation of mrna into the sequence of amino acids in a polypeptide depends on specificity in which of the following? 1) binding of ribosomes to mrna 2) shape of the a and p sites of ribosomes 3) attachment of amino acids to trnas 4) bonding of the anticodon the codon and the attachment of amino acids to trnas