Question

5.Consider again the picture you selected in question #3. What’s attached to the 5’ end of this molecule? (BOLD the correct answer)

   A phosphate group    OR    An OH group (which is attached to the ribose sugar)

6.Consider again the picture you selected in question #3. The way it’s drawn on this page, the bottom end of this molecule is considered to be the…(BOLD the correct answer)

            3’ end      OR      5’ end

Answer 1

DNA and RNA are both nucleic acids. RNA is ribonucleic acids. DNA is Deoxyribonucleic acid. The structural monomeric units of both DNA and RNA are nucleotides.

There are 3 basic components of nucleotides:

1: Pentose sugar- It is 5-carbon sugar.

2. Nitrogenous base- The ringed structure base is attached to the 1’ carbon of the pentose sugar. Nitrogenous bases may be of two types:

a) Purines- DNA and RNA have same purine bases called Adenine (represented as A) and Guanine (represented as G).

b) Pyrimidine- DNA has Thymine (T) and Cytosine (C). RNA has Uracil (U) and Cytosine (C).

3. Phosphate groups: The 5’ carbon atom of pentose, may bond with phosphate group (which may be mono phosphate, bi phosphate or triphosphate).

Nucleotides form covalent bond to attach to each other and form a chain or strand of nucleic acid. Covalent linkage between nucleotides are formed by, 3’ carbon atom of one nucleotide with phosphate group (attached to the 5’ carbon) of another nucleotide. The primary structure of nucleic acids is thus formed.

5) A phosphate group

6) If OH is in top- 3' end