Answers to Study Guide 4 Nucleic Acids (Kopachik) Questions: There are two forms of bases __ pyrimidines with three types (_ thymine, cytosine and uracil ) and purine with two types (_ adenine and _ guanine ). Any _ base _ plus either of two types of sugars _ ribose _ and _ deoxyribose will form a nucleoside with covalent bond from carbon 1 of the sugar. Addition of a _ phosphate _ group attached to the 5 C makes it a nucleotide. Monomers used for DNA or RNA synthesis have three phosphate groups as in dATP or ATP for instance. DNA uses four bases but it lacks _ uracil whereas RNA replaces the _ thymine of DNA with it. RNA is largely _ single stranded _ whereas DNA is normally in a double stranded form. The bases across from each other fit together precisely by their ability to form _ H bonds; there are three between _ guanine _ and cytosine and two between _ adenine and _ thymine . RNA and DNA strands have a polarity going from a 5’ _ phosphate end to a _ 3’ hydroxyl end. In addition DNA’s strands are
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