Biological Macromolecules: Proteins, Nucleic Acids, and Carbohydrates

Comprehensive vocabulary review flashcards covering amino acid properties, protein structure levels, nucleic acid monomers and bonding, DNA replication features, and carbohydrate classifications.

Carboxyl Group

A functional group ($-COOH$) bound to the central carbon of every amino acid that acts as an acid by donating a proton at cellular $\text{pH } 7$.

Amino Group

A functional group ($-NH_2$) bound to the central carbon of every amino acid that acts as a base by gaining or accepting a proton at cellular $\text{pH } 7$.

Amino Acid

The monomer used to build proteins, composed of a central carbon bonded to an amino group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom ($-H$), and an R-group (side chain).

R-group (Side Chain)

The variable component of an amino acid structure that distinguishes the $20$ different amino acids from one another and determines their chemical properties.

Hydrophobic Amino Acid

An amino acid whose R-group consists solely of hydrogen and carbon atoms, causing it to congregate with other nonpolar side chains and be stabilized by van der Waals interactions.

Hydrophilic Amino Acid

An amino acid whose R-group contains polar or charged groups, such as a short chain of hydrogen and carbon atoms ending in a negatively charged carboxylic acid.

Peptide Bond

A covalent bond formed between two amino acid molecules via a condensation reaction that releases a water molecule, establishing the primary structure of proteins.

Primary Structure (Protein)

The linear sequence of amino acids in a polypeptide formed by peptide bonds; it is the level least affected by hydrogen bond disruption and determines enzyme function by positioning R-groups at the active site.

Secondary Structure (Protein)

The protein structural level represented by the $\alpha$-helix and $\beta$-pleated sheet, both stabilized predominantly by hydrogen bonds.

Tertiary Structure (Protein)

The three-dimensional, fully folded polypeptide structure stabilized primarily by interactions among the amino acid side chains (R-groups).

Protein Denaturation

The process by which proteins lose their folded structure and biological function, which occurs when body temperature continues to rise during a dangerous fever.

Nucleotide

The monomer unit that polymerizes into nucleic acids, composed of a nitrogenous base, a pentose sugar, and a phosphate group.

Deoxyribonucleotide

A nucleotide monomer of DNA whose pentose sugar lacks an oxygen atom on the second carbon atom, having a hydrogen atom instead of a hydroxyl group.

Ribonucleotide

A nucleotide monomer found in RNA that possesses a hydroxyl group ($-OH$) on the second carbon atom of its ribose sugar.

Phosphate Group (Nucleic Acids)

The structural feature of single nucleotides that provides the energy required for polymerization during nucleic acid formation.

Phosphodiester Bond

The covalent bond formed between the sugar of one nucleotide and the phosphate group of a second nucleotide in nucleic acids, analogous to a peptide bond in polypeptides.

Pyrimidines

The family of nitrogenous bases found in nucleic acids that includes uracil, cytosine, and thymine.

Histones

Large proteins around which large amounts of DNA wrap to establish the tertiary structure of DNA.

DNA Secondary Structure

The double-stranded conformation of DNA held together predominantly by hydrogen bonding between complementary nitrogenous base pairs.

RNA Secondary Structure

The structural conformation of RNA, which differs from DNA by being single-stranded and functions primarily to synthesize proteins.

RNA Catalytic Function

The ability of RNA to act both as a store of genetic information and as a catalyst to speed up chemical reactions, leading researchers to hypothesize it was the first self-replicating molecule.

Complementary Base Pairing

The specific pairing of nitrogenous bases between strands (such as adenine with thymine and cytosine with guanine) that provides the structural mechanism allowing DNA to replicate.

Aldose and Ketose

Classes of sugars distinguished from each other by the position of their carbonyl group ($-C=O$).

$\alpha$-Glucose and $\beta$-Glucose

Structural forms of glucose that differ from each other in the location of their hydroxyl group ($-OH$).

Monosaccharide

A simple sugar carbohydrate with the chemical formula $C_6H_{12}O_6$, containing a single carbonyl group ($-C=O$) and $5$ hydroxyl groups ($-OH$) in its linear form.

Disaccharide

A carbohydrate formed by two monosaccharides joined by a glycosidic linkage, such as lactose, which consists of one glucose molecule joined to one galactose molecule.

$\alpha$-1,6-Glycosidic Linkage

The specific type of covalent linkage found at the branch points of branched polysaccharides like glycogen and amylopectin.

Peptidoglycan

A complex carbohydrate containing at least one peptide bond, serving as a primary target for developing antibacterial antibiotics.

Chitin

A polysaccharide that serves as an important structural component in many animals and fungi.

Glycogen and Starch Structural Difference

The primary structural distinction between starch and glycogen, which is their degree of branching.