1 15 pts a if the ratio a gt c in one strand of dna is 06...

1) (1.5 pts) a) If the ratio (A + G)/(T+ C) in one strand of DNA is 0.6, what is the same ratio in the complementary strand? b) If the DNA of a species has (G + C) = 0.36, what is the proportion of A in the same DNA? c) If the composition of DNA of an organism is the following: A (10%), G (33%), C (20%) and T (37%), what does this tell you about the organization of that DNA molecule?

Transcript

00:01 Okay, you want to answer this question as to come out, based pairing rules.

00:03 We remember that atenin pairs with thyming and cytosing with one.

00:07 So this is one strand of dna and it is another strand of dna.

00:11 In this case, our question a, it says if the weight of a plus g and t plus c, in one strand of dna, it means only in one strand, let's suppose in this strand here, is 0 .6 .6.

00:26 It means 0 .6 is the same as 6 out of 10.

00:30 Okay, so let's make it like this, okay, a1, g1, t1, c1.

00:37 These are for the amount of adenine, 1 in cytosine in this strand.

00:43 And in this case, you're going to have adenine 2 plus 1 in 2, divided by the time in 2 plus cytosine 2.

00:53 So whenever you have an adenine here, you're going to have a thymine here.

01:01 Okay, because athenin is always going to pair with timing 2.

01:05 While if you have one cytosine here, you're going to have one in here because cytosin pairs with one always.

01:12 So practically you can say that whenever you have an adenine in the first strand, you're going to have a thymine in the second strand.

01:21 Whenever you have a thymine in the first strand, you're going to have an alanine in the second strand.

01:26 Whenever you have a cytosine in the first strand, you're going to have a one in the second strand, and the same for a watt.

01:34 Okay, so and you have this video here, a1 is equal to t2, so you have t2 here plus g1, g1 is equal to c2 and divided by t1 that is equal to a2 plus c1 that is equal to g2.

02:00 Okay, and this is equal to 6 divided by 10.

02:04 According to it, we have just replaced these variables by their equivalent here.

02:10 So you have this.

02:11 The question is asking you the same ratio in the complementary strand.

02:15 So you want the same ratio al -al -a -plast 1 over time in plus cytosin, but in this stand here.

02:22 Here you have the ratio, but for practically the opposite.

02:26 You want this to be in the numerator, and this to be in the denominator.

02:30 So you have to do simple math...