Quiz time/ 03

1) The DNA double helix looks like a twisted ladder. What makes up each rung of the ladder? What holds the rungs together at the sides?

2) Which bases are purines? Pyrimidines?

1) The nitrogeneous bases ( Adenine, Guanine, Cytosine and thymine) makes up each rung of the ladder. Deoxyribose sugar and the phosphate group holds the rungs together at the sides.

2) Purines : Adenine & Guanine
Pyrimidines : Cytosine & Thymine (Uracil is present in RNA in place of thymine)

1. the rung of the ladder is made up of the nitrogenous bases and they are held together by phosphodiester bonds, in which a phosphate group forms a bridge between -OH groups on two adjacent sugar residues.

2. Purines : Adenine & Guanine
Pyrimidines : Cytosine, Thymine and Uracil in RNA. (Replaced for Thymine & forms complementary base pairs with Adenine.)

1. DNA is basically a long polymer of nucleotides. It's backbone is made of sugars and phosphate groups joined by ester bonds. Attached to each sugar is one of four types of molecules called bases, or the rungs.

2.Purines : Adenine & Guanine
Pyrimidines : Cytosine & Thymine ( Uracil is in RNA which will be the complementary base pair of Thymine)