2.2.2 - DNA: Structure

Question 1

What Are DNA Molecules Made Up Of?

Answer 1

Two polynucleotide strands lying side by side, running in opposite directions and are said to be antiparallel.

Question 2

What Is Each DNA Polynucleotide Strand Made Up Of?

Answer 2

Alternating deoxyribose sugars and phosphate sugars bonded together to form the sugar-phosphate backbone.

Question 3

What Bonds Hold The Sugar Phosphate Backbone Together?

Answer 3

Phosphodiester bonds.

Question 4

What Do The Phosphodiester Bonds Link?

Answer 4

5-carbon of one deoxyribose sugar molecule to the phosphate group from the same nucleotide, which itself is linked by another phosphodiester bond to the 3-carbon of the deoxyribose sugar molecule of the next nucleotide in the strand.

Question 5

What Does Each DNA Polynucleotide Strand Have?
(3 Points)

Answer 5

~ A 3’ end and a 5’ end.

~ One strand is known as the 5’ to 3’ stand, due to them being antiparallel.

~ The other strand is known as the 3’ to 5’ strand.

Question 6

What Are The 2 Antiparallel DNA Polynucleotide Strands Held Together By?

Answer 6

Hydrogen bonds between the nitrogenous bases.

Question 7

Where Do The Hydrogen Bonds Always Occur Between?

Answer 7

The same pairs of bases.

Question 8

What Is DNA Described As?

Answer 8

A double helix.