Which of these lines of dialogue is punctuated correctly? Question 1 options: “Hey, come over here” I called to him.
“Why is it up to me”? Stella asked her brother.
“After all,” the doctor said, “if you don’t take your medicine, you won’t get better.”

Okay, biology isn't exactly my strongest subject (it never has been), but i'm pretty sure the answer is nucleotides. dna is made up of nucleotides. each nucleotide contains a phosphate group, a sugar group, and a nitrogen base. there are four different nitrogen bases: adenine (a), thymine (t), guanine (g), and cytosine (c). a always pairs with t, and g always pairs with c.