Practice Questions

The test detects the free carbonyl group (C=O) at the anomeric carbon of a reducing sugar. This group can be oxidized, thereby reducing the Cu²⁺ in Benedict's reagent to Cu⁺, forming a colored precipitate. Non-reducing sugars lack this free group.

Quaternary structure exists only in proteins composed of more than one polypeptide chain (subunit). It describes the specific 3D arrangement and interactions between these individual, folded subunits, as seen in hemoglobin (α2β2).

Condensation (or dehydration synthesis) is the anabolic process where monomers are covalently bonded together with the simultaneous removal of a water molecule. This is the fundamental mechanism for polymer formation. Hydrolysis is the reverse, catabolic process.

Both glycogen and cellulose are glucose polymers, but glycogen has α-1,4 and α-1,6 glycosidic bonds, allowing it to be a branched, digestible energy source. Cellulose has β-1,4 glycosidic bonds, which create straight chains that form strong structural fibers and are indigestible by most animals.

While the sugar-phosphate backbone provides structural integrity, genetic information is encoded in the specific linear sequence of the four nitrogenous bases (A, T, G, C). This sequence is the code that dictates protein synthesis and is heritable.

Feedback inhibition is a regulatory mechanism where the end product of a metabolic pathway acts as an inhibitor of an enzyme earlier in the pathway, usually the first committed step. This prevents the unnecessary accumulation of the product and wasteful use of resources.

Linoleic acid is an omega-6 polyunsaturated fatty acid that is essential for mammals, including humans. We lack the desaturase enzymes required to introduce double bonds beyond the ninth carbon, so it must be obtained from the diet.

The two strands of the DNA double helix are physically linked by hydrogen bonds between complementary base pairs (A-T and G-C). The backbone of each individual strand is held together by covalent phosphodiester bonds.

Cholesterol is a sterol lipid that intercalates between phospholipids. At high temperatures, it restrains movement, reducing fluidity. At low temperatures, it prevents tight packing, preventing solidification. Thus, it acts as a key fluidity buffer for membrane stability.

Lipids contain long hydrocarbon chains rich in C-H bonds, which are in a highly reduced state. Upon oxidation, they yield more energy than the more oxidized C-OH bonds found in carbohydrates. The bulk of energy release comes from the transfer of electrons from these C-H bonds.