Practice Questions

Purines are double-ringed; pairing two purines would exceed the 2 nm diameter, while pairing two pyrimidines would make the helix too narrow.

The hydrophilic sugar-phosphate backbones face the aqueous exterior, while the nitrogenous bases point inward to hide from water and form pairs.

Refined by Beadle and Tatum, and later updated to "one gene-one polypeptide," this concept binds a genetic locus to a single protein product.

The glycosidic bonds do not project directly opposite one another, making the spaces between the backbones unequal around the cylinder.

If A=30%, then T=30%, totaling 60%. The remaining 40% is split equally between Guanine (20%) and Cytosine (20%).

While hydrogen bonds hold the pairs together horizontally, vertical base-stacking interactions insulate the hydrophobic bases from water.

The 3' end of a nucleic acid strand terminates at the third carbon of the sugar ring, which carries a free hydroxyl group.

Structural genes carry the specific nucleotide blueprints required to assemble amino acids into a polypeptide chain on a ribosome.

Cytosine and thymine are single-ring pyrimidines, whereas adenine and guanine are double-ring purines.

A codon is a triplet of bases that specifies a particular amino acid or a stop signal during protein translation.