BIO NMDCAT

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

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

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

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

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

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

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

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

With 10 base pairs per complete helical turn of 3.4 nm, the step distance between consecutive base pairs is 3.4/10=0.34 nm.

G-C pairs are linked by three hydrogen bonds, which require more thermal energy to disrupt than the two hydrogen bonds holding A-T pairs together.

Introns are intervening, non-translated sequences within a gene that are transcribed into pre-mRNA but removed by splicing.

Rosalind Franklin’s famous "Photo 51" obtained via X-ray crystallography revealed the helical configuration and dimensions of the DNA molecule.

One strand runs in the 5' to 3' direction while its complementary partner runs in the 3' to 5' direction.

Guanine pairs with cytosine via three hydrogen bonds, creating a more thermally stable bond than the adenine-thymine pair.

A gene is the fundamental structural and functional unit of heredity, consisting of a nucleotide sequence that carries the code for a protein.

The 5' end of a DNA or RNA strand terminates in a phosphate group attached to the 5' carbon of the pentose sugar.

Adenine (a purine) always pairs with thymine (a pyrimidine) using two hydrogen bonds in standard Watson-Crick base pairing.

The double helix maintains a constant width of 2 nm (20 A˚) because a double-ringed purine always pairs with a single-ringed pyrimidine.