Biological Molecules

A set of practice flashcards covering the key concepts from the Biological Molecules lecture notes, including carbon’s role, macromolecule classes, monomers/polymer relationships, and details about carbohydrates, lipids, proteins, and nucleic acids, plus lactose tolerance context.

Why is carbon central to life’s molecular diversity?

Because carbon can form four covalent bonds and branch in four directions, enabling a vast variety of complex organic molecules.

What reaction links monomers to form polymers?

Dehydration synthesis (removal of a water molecule) forms bonds between monomers.

What reaction breaks polymers into monomers?

Hydrolysis (addition of water) breaks bonds in polymers.

What are the four major classes of biological molecules?

Carbohydrates, lipids, proteins, and nucleic acids.

What is a monomer and what is a polymer?

A monomer is a building block; a polymer is a large molecule formed by linking many monomers (often 20+).

What is the general empirical formula for carbohydrates?

CH2O.

Give examples of monosaccharides mentioned in the notes.

Fructose and glucose (simple sugar monomers).

What disaccharides are formed from monosaccharides and provide examples?

Disaccharides are formed from two monosaccharides; examples include sucrose (glucose + fructose) and maltose (glucose + glucose).

What are polysaccharides and their general roles?

Long chains of sugar units that function as storage molecules or structural components.

Name plant and animal polysaccharides and their roles.

Starch (plants, energy storage), Glycogen (animals, energy storage), Cellulose (plants, cell walls), Chitin (insects/crustaceans for exoskeletons; fungi cell walls).

What are lipids and their general properties?

Water-insoluble (hydrophobic) molecules important for long-term energy storage; mainly C and H; not polymers.

Describe the structure of fats (triglycerides).

One glycerol backbone with three fatty acids linked by dehydration reactions; fats are often called triglycerides.

What is the difference between saturated and unsaturated fatty acids?

Saturated fats have no double bonds (max hydrogens) and are typically solid at room temperature; unsaturated fats have one or more double bonds (kinks) and are usually liquids; trans fats result from hydrogenation and have health risks.

What are phospholipids and their role in cells?

Major component of cell membranes; two fatty acids + a phosphate group; form a phospholipid bilayer with hydrophilic heads and hydrophobic tails.

What are steroids and what is cholesterol’s role?

Steroids have four fused carbon rings; cholesterol is a membrane component and a precursor to steroid hormones like estrogen and testosterone.

What are proteins and their primary functions?

Proteins have diverse functions, including enzymes (catalysts), transport, defense (antibodies), signaling, receptors, contraction, structure, and storage.

What are amino acids and what bond links them?

Amino acids are the monomers of proteins; they have an amino group, a carboxyl group, a central carbon, and an R group; they are linked by peptide bonds via dehydration reactions.

What are the four levels of protein structure?

Primary: amino acid sequence; Secondary: alpha helix or beta pleated sheets; Tertiary: 3D shape from R-group interactions; Quaternary: arrangement of multiple polypeptides.

What are nucleic acids, and what are their monomers?

Nucleic acids store genetic information; monomers are nucleotides (sugar, phosphate, nitrogenous base).

What bases are found in DNA and RNA?

DNA: adenine (A), thymine (T), cytosine (C), guanine (G); RNA: A, C, G, uracil (U) instead of T.

What is the backbone of a nucleotide polymer?

Sugar-phosphate backbone with nitrogenous bases extending from it.

What are ATP and ADP and their roles?

ATP stores short-term energy; hydrolysis to ADP and inorganic phosphate releases energy used by cells.

What is lactose intolerance and which enzyme is involved?

Lactose intolerance occurs when lactase enzyme is lacking or reduced, preventing lactose digestion.

Which lipid is associated with membranes and why?

Phospholipids form cell membranes; their amphipathic nature (hydrophilic heads, hydrophobic tails) drives bilayer formation.

What is the note about lipids being non-polar and not polymers?

Lipids are mostly non-polar and are not polymers; they are not built from repeating monomer units like the other biomolecules.