Answer: The complementary strand of DNA from top to bottom will read:
G - A - T - T - G - C
Explanation:
DNA Structure
As you can see in the picture, the three main components of DNA, or deoxyribonucleic acid are a phosphate group (P), a sugar (S), and nucleotides.
The phosphates and sugars form what's known as the "backbone" of the DNA, while the nucleotides hold the two strands of DNA together. If you're thinking of DNA as a ladder, then nucleotides are the rungs.
Nucleotide Pairs
There are four nucleotides found in DNA:
Adenine, Thymine, Cytosine, and Guanine.
They will always form the same two pairs:
(Adenine & Thymine) and (Cytosine & Guanine).
They do this because of the unique shapes of the nucleotides and which pairings will form the strongest bonds. Our DNA needs to be strong to withstand changes in the body.
Making a Complementary Strand
In the body, the enzyme that makes complementary DNA strands is DNA Polymerase. Once you memorize the pairings, it's pretty easy to see what your new strand should look like.
The strand that we were given will be our template strand. Let's go down the template strand and see what we need to add to make matching pairs.
Template Complementary
Cytosine (C) - (G) Guanine
Thymine (T) - (A) Adenine
Adenine (A) - (T) Thymine
Adenine (A) - (T) Thymine
Cytosine (C) - (G) Guanine
Guanine (G) - (C) Cytosine
These pairings will be true for all DNA, so all you need to do to make new strands on your own is memorize the two pairs. It's helpful to think of a mnemonic, like "Cars go in the Garage" and "Apples come from Trees".
