Medical Biochemistry: Structure, Function, and Clinical Correlates of Biomolecules

Comprehensive vocabulary flashcards covering the chemical classification, structure, function, and pathological disorders associated with carbohydrates, lipids, proteins, and nucleic acids.

Biomolecules

Chemical compounds produced by living organisms primarily composed of carbon ($C$), hydrogen ($H$), oxygen ($O$), nitrogen ($N$), sulfur ($S$), and phosphorus ($P$); includes carbohydrates, lipids, proteins, and nucleic acids.

Enantiomers

Pairs of stereoisomers that are non-superimposable mirror images of one another at every chiral center, exemplified by D- and L-sugars.

Epimers

Stereoisomers that differ in configuration around only a single asymmetric chiral carbon atom (e.g., D-glucose and D-galactose at C-4, or D-glucose and D-mannose at C-2).

Anomeric Carbon

The carbon atom in a cyclic carbohydrate that originally functioned as the carbonyl carbon (aldehyde or ketone) in its open-chain form, forming a hydroxyl group in the $\alpha$ (down) or $\beta$ (up) configuration upon ring closure.

Pyranose

A six-membered cyclic carbohydrate ring structure formed by an intramolecular hemiacetal or hemiketal reaction between a carbonyl group and a hydroxyl group.

Furanose

A five-membered cyclic carbohydrate ring structure formed by an intramolecular reaction between a carbonyl group and a hydroxyl group, characteristic of cyclic fructose.

Gluconic Acid

An oxidized sugar acid formed specifically by oxidation of the aldehyde carbon (C-1) of glucose.

Glucuronic Acid

An oxidized sugar acid formed by oxidation of the terminal carbon (C-6) bearing the primary alcohol group of glucose.

Polyol

A sugar alcohol (such as D-sorbitol) produced through the reduction of the carbonyl aldehyde or ketone group of a monosaccharide.

Deoxy Sugar

A modified monosaccharide in which one or more hydroxyl groups have been reduced to hydrogen atoms, exemplified by 2-deoxyribose in DNA.

Proteoglycans

Extracellular matrix macromolecules consisting of a core protein covalently bonded to repeating disaccharide polysaccharide chains (containing uronic acid, amino sugars, and sulfate groups) that provide mechanical support and skin elasticity.

Glycosidic Bond

A covalent linkage formed when the hydroxyl group on the anomeric carbon of a monosaccharide reacts with a functional group (such as an $-OH$ or $-NH$ group) of another molecule.

Lactose

A milk disaccharide formed by joining D-galactose and D-glucose via a $\beta(1\rightarrow 4)$-glycosidic bond.

Starch

A plant storage carbohydrate composed of two components: amylose (linear glucose polymer with $\alpha(1\rightarrow 4)$ linkages) and amylopectin (branched glucose polymer with $\alpha(1\rightarrow 4)$ chains and $\alpha(1\rightarrow 6)$ branch points).

Glycogen

The principal storage polysaccharide in animals, formed of branched glucose chains linked linearly by $\alpha(1\rightarrow 4)$ bonds and branched via $\alpha(1\rightarrow 6)$ linkages.

Eicosanoids

A family of 20-carbon signaling molecules derived from arachidonic acid ($20:4\,\Delta^{5,8,11,14}$), including prostaglandins, leukotrienes, and thromboxanes, that modulate inflammation, fever, pain, and platelet aggregation.

Acylglycerols

Lipids consisting of a glycerol backbone ester-linked to one, two, or three fatty acids (acyl groups), serving as the primary format for energy storage in adipose tissue.

Glycerophospholipids

Amphiphilic membrane lipids composed of a glycerol-3-phosphate backbone esterified to one or two fatty acids and bonded to a polar head group such as choline, ethanolamine, or serine.

Lysoglycerophospholipids

Bioactive signaling molecules generated by the enzymatic cleavage and removal of a single fatty acid chain from a glycerophospholipid.

Sphingosine

An 18-carbon amino alcohol backbone synthesized condensation-wise from serine and palmitic acid, serving as the core structural component of all sphingolipids.

Ceramides

Sphingolipid structural units composed of sphingosine attached to a fatty acid residue via an amide bond at its amino group.

Sphingomyelins

Membrane sphingolipids formed by attaching a phosphocholine or phosphoethanolamine head group to the terminal hydroxyl of a ceramide, critical for insulating nerve axon myelin sheaths.

Cerebrosides

Neutral glycosphingolipids consisting of a ceramide core linked to a single monosaccharide residue (glucose or galactose) at its terminal hydroxyl group.

Gangliosides

Acidic glycosphingolipids composed of a ceramide core linked to an oligosaccharide chain containing one or more negatively charged sialic acid residues, essential for receptor function and signal transduction.

Cholesterol

A four-ring steroid lipid synthesized from 5-carbon isoprenyl units; stabilizes cell membranes and serves as the precursor for bile acids, steroid hormones, coenzyme Q, and vitamin A.

$\gamma$-Aminobutyrate (GABA)

A major inhibitory neurotransmitter in the central nervous system synthesized from glutamate, possessing an amino group located on its $\gamma$-carbon.

Purines

Double-ring nitrogenous heterocyclic aromatic bases consisting of a fused pyrimidine and imidazole ring; includes adenine (A) and guanine (G).

Pyrimidines

Single-ring six-membered nitrogenous heterocyclic aromatic bases; includes cytosine (C), thymine (T), and uracil (U).

Nucleotide

A molecular monomer composed of a nitrogenous base linked to a pentose sugar (ribose or deoxyribose) and one, two, or three phosphate groups (NMP, NDP, or NTP).

Glycogen Storage Disease 0 (GSD 0)

A metabolic disorder caused by glycogen synthase deficiency, characterized by decreased glycogen storage, hypoglycemia, hyperketonemia, failure to thrive, and early death.

GSD I (von Gierke's Disease)

A glycogen storage disorder caused by glucose-6-phosphatase deficiency that prevents hepatic release of free glucose, leading to severe hypoglycemia, hepatomegaly, and lactic acidosis.

GSD II (Pompe Disease)

A lysosomal storage disease caused by lysosomal $\alpha$-1,4-glucosidase (acid maltase) deficiency, causing glycogen accumulation in lysosomes, cardiomegaly, severe muscle weakness, and infantile death.

GSD III (Cori Disease)

A glycogen storage disease caused by amylo-1,6-glucosidase (debranching enzyme) deficiency, causing excessive accumulation of abnormally branched glycogen and hypoglycemia.

GSD IV (Andersen Disease)

A metabolic disorder caused by amylo-4,6-glucosidase (branching enzyme) deficiency, resulting in the accumulation of abnormal, insoluble glycogen and progressive hepatosplenomegaly.

McArdle Disease

A metabolic myopathy caused by muscle phosphorylase deficiency, leading to glycogen accumulation in skeletal muscle, exercise-induced pain, cramps, and progressive weakness.

Galactosemia Type I

An inborn error of carbohydrate metabolism caused by galactose 1-phosphate uridylyltransferase deficiency, leading to galactose 1-phosphate accumulation, jaundice, hepatomegaly, and cataracts.

Hereditary Fructose Intolerance (HFI)

An autosomal recessive disorder caused by aldolase B deficiency, resulting in toxic intracellular accumulation of fructose 1-phosphate, hypoglycemia, jaundice, and hepatomegaly.

Tay-Sachs Disease

A fatal lipid storage disorder caused by hexosaminidase A deficiency, resulting in GM2 ganglioside accumulation within neurons, progressive neurodegeneration, and a cherry-red macula.

Cherry-red Macula

A distinctive retinal finding visible on fundoscopic examination due to the accumulation of lipid materials (such as GM2 gangliosides in Tay-Sachs disease) in surrounding retinal ganglion cells, creating contrast against the thin fovea.

Gaucher Disease

A lysosomal storage disorder caused by $\beta$-glucosidase deficiency, leading to glucocerebroside accumulation, hepatosplenomegaly, and painful bone crises.

Niemann-Pick Disease

A lysosomal lipidosis caused by sphingomyelinase deficiency, resulting in sphingomyelin accumulation in reticuloendothelial cells, hepatosplenomegaly, and neurodegeneration.

Familial Hypercholesterolemia

An autosomal dominant disorder caused by LDL receptor gene mutations, leading to severely elevated serum LDL cholesterol, premature atherosclerosis, and lipid tendon deposits (xanthomas).

Xanthoma

A yellowish cutaneous or tendinous deposit of cholesterol and lipids, characteristic of severely elevated circulating LDL cholesterol seen in familial hypercholesterolemia.

Sickle Cell Anemia

A hemoglobinopathy caused by a missense point mutation in the $\beta$-globin gene ($\text{Glu} \rightarrow \text{Val}$), producing mutant hemoglobin HbS, anemia, vaso-occlusive pain episodes, and dactylitis.

Phenylketonuria (PKU)

An amino acid metabolic disease caused by phenylalanine hydroxylase deficiency, leading to systemic phenylalanine accumulation, intellectual disability, hypopigmentation, and a musty body odor.

Osteogenesis Imperfecta

A genetic bone fragility disorder caused by COL1A1 or COL1A2 gene mutations producing defective type I collagen, presenting with multiple fractures and blue sclerae.

Blue Sclera

A clinical eye sign characterized by a bluish coloration of the white of the eye resulting from abnormal transparency and thinning of scleral collagen, characteristic of osteogenesis imperfecta.

Marfan Syndrome

An autosomal dominant connective tissue disease caused by mutations in the fibrillin-1 (FBN1) gene, resulting in defective elastin organization, tall stature, ectopia lentis, and aortic aneurysms.

$\alpha_1$-Antitrypsin Deficiency

A genetic proteopathy caused by the accumulation of misfolded $\alpha_1$-antitrypsin in hepatic endoplasmic reticulum, leading to uninhibited elastase activity, pulmonary emphysema, and liver cirrhosis.

Lesch-Nyhan Syndrome

An X-linked purine salvage disorder caused by HGPRT deficiency, causing severe uric acid accumulation, juvenile gout, neurological impairment, and compulsive self-mutilation.

Severe Combined Immunodeficiency Disease (SCID)

A primary immunodeficiency disorder caused by adenosine deaminase (ADA) deficiency, leading to toxic dATP accumulation, widespread lymphocyte apoptosis, and life-threatening recurrent infections.

Xeroderma Pigmentosum

An autosomal recessive DNA repair disorder caused by defective nucleotide excision repair, leading to extreme sensitivity to ultraviolet (UV) radiation and early-onset skin cancers.

Lynch Syndrome (HNPCC)

An inherited cancer syndrome caused by defects in DNA mismatch repair genes (MSH2/MLH1), conferring high susceptibility to early-onset colorectal and endometrial carcinomas.