00:01
Thymine makes up 15 % of the bases in a dna molecule.
00:04
What percentage of a basis is cytosine? so thineine is 15%.
00:11
What about the others? and the one we're looking at is cytosine.
00:18
Okay.
00:19
So what do we know about dna? first of all, i've written out before possible nucleotides.
00:25
These are the only nucleotides you're going to find dna.
00:27
So if you add up the percentage for each of them, you're going to get 100%.
00:32
So we know that.
00:37
What else do we know? we know that dna is a double -stranded molecule.
00:41
So if you look at the two strands, and this strand has an adenine and a guanine, you know exactly what you'll find on this strand.
00:49
Adonine is always found with thymine, guanine is always found of a cytosine, which means, but the amounts of thymine and the amounts of adenine are actually the same, because you have exactly the same number of molecules of the two.
01:04
And the same applies for guanine and cytosine.
01:08
So adenine equals thiamine, guine equals cytosine.
01:12
So 15%...