Biomolecules – Exam Review Flashcards

20 question-and-answer flashcards covering key concepts on carbohydrates, lipids, proteins, and nucleic acids.

What ability of carbon atoms allows them to serve as the backbone of large, complex biomolecules?

Each carbon can form up to four covalent bonds (including bonds with other carbons), enabling stable yet versatile molecular structures.

Which six elements are classified as cellular macronutrients?

Hydrogen (H), Carbon (C), Oxygen (O), Nitrogen (N), Phosphorus (P), and Sulfur (S).

What reaction links monomers together by removing a molecule of water?

A dehydration (condensation) reaction.

What reaction breaks polymers apart by adding water?

Hydrolysis.

Which monosaccharide is the main immediate fuel for cellular work?

Glucose.

What disaccharide is produced when glucose joins with fructose?

Sucrose.

What polysaccharide stores glucose in animal liver and muscle cells?

Glycogen.

Which structural polysaccharide forms plant cell walls and is Earth’s most abundant organic compound?

Cellulose.

Why are most carbohydrates hydrophilic (water-loving)?

Their sugar monomers contain many hydroxyl (-OH) groups that readily form hydrogen bonds with water.

How does an unsaturated fatty acid differ from a saturated fatty acid?

Unsaturated fatty acids contain one or more double bonds that create kinks; saturated fatty acids lack double bonds and are fully hydrogenated.

What two smaller molecules combine to form a fat (triglyceride)?

One glycerol molecule and three fatty acids.

Which lipid type is the primary structural component of cell membranes?

Phospholipids.

Which steroid is a common membrane component and a precursor of sex hormones?

Cholesterol.

What are the monomers that make up proteins?

Amino acids.

What covalent bond links amino acids in a polypeptide chain?

A peptide bond.

What process causes a protein to lose its specific shape and function, often due to heat or pH changes?

Denaturation.

Name the four levels of protein structure in order of increasing complexity.

Primary, secondary, tertiary, and quaternary.

What are the monomers of nucleic acids (DNA and RNA)?

Nucleotides.

Which nitrogenous base is found in RNA but not in DNA?

Uracil (U).

What type of bonds hold the two complementary strands of DNA together?

Hydrogen bonds between specific base pairs (A–T and C–G).