00:03
Hi there.
00:04
This question is about dna, and we know dna is composed of nucleotides, with each nucleotide being composed of a phosphate group, a five -carbon sugar, and then a nitrogen base.
00:19
And there are four nitrogen bases, adenine, thymine, cytosine, and guany.
00:24
And when dna forms its double strand, these nitrogen bases are like the rungs of a ladder.
00:31
So if we think about the dna backbone being made of the five carbon sugar and the phosphate groups, the rungs are these nucleototide or are these nitrogen bases.
00:48
All right.
00:48
And again, there are four of those.
00:51
And they always pair up where adenine, typically abbreviated with capital a, always pairs with thymine.
01:06
And cytosine always pairs with guany.
01:19
All right...