DNA Double Helix Structure Quiz

DNA Double Helix Structure

• The DNA double helix consists of two DNA strands twisted together around a common axis.
• The two strands are antiparallel, meaning they run in opposite directions (5′ to 3′ and 3′ to 5′).
• The strands are held together by hydrogen bonds between complementary base pairs: adenine (A) with thymine (T) and guanine (G) with cytosine (C).
• Three hydrogen bonds occur between G and C, while two occur between A and T.
• The AT/GC rule enables the prediction of one DNA strand's sequence if the opposing strand's sequence is known.
• The width of the double helix is relatively constant due to the pairing of purines (A and G) with pyrimidines (T and C).
• DNA with a higher G-C content forms more stable double-stranded structures.
• A complete turn of the helix spans ten base pairs, covering a linear distance of 3.4 nm.
• Each base pair occupies 0.34 nm along the DNA strand.

B DNA and Z DNA

• B DNA is the most common form of DNA, featuring a right-handed helix.
• Z DNA is a less common form of DNA with a left-handed helix.