Biochemistry 1.4: Water Properties, Micronutrients, Transition Metals, and Free Radicals

Vocabulary practice flashcards covering water molecular structure, noncovalent bonds, thermal/solvent properties, free radicals, antioxidants, vitamins A-K, B-complex, vitamin C, macrominerals, and microminerals.

Dipole Moment (in Water)

A separation of partial electric charges caused by the unequal sharing of electrons, where hydrogen carries a partial positive charge ($\delta^+$) and oxygen carries a partial negative charge ($\delta^-$).

Water Bond Angle

The angle of $104.5^\circ$ formed by the bent or angular molecular geometry of water due to lone pairs on the oxygen atom.

Dielectric Constant

A measure of the capacity of a solvent to reduce attractive electrostatic forces between ions, which is very high in water.

Heat of Vaporization

The energy required to vaporize one mole of liquid at a pressure of one atmosphere.

Heat Capacity

The energy that must be added or removed to change the temperature of a substance by one degree Celsius.

Hydrogen Bond

An intermolecular noncovalent attraction between the partially positive hydrogen atom of one water molecule and the unshared electron pair of another electronegative atom; it represents the strongest type of noncovalent bond.

London Dispersion Forces

Extremely weak noncovalent interactions, also known as induced dipole-induced dipole interactions, occurring when a transient dipole in one molecule polarizes the electrons in a neighboring molecule.

Amphipathic Molecules

Molecules containing both polar (hydrophilic) and nonpolar (hydrophobic) regions, such as phospholipids, which coalesce to form spherical micelles in aqueous environments.

Micronutrients

Vitamins and minerals that the body requires in small amounts for biological growth, development, and immune function.

Transition Metals

Chemical elements in the d-block of the periodic table capable of forming bonds using electrons from multiple shells and easily altering oxidation states to act as cofactors in redox reactions.

Free Radicals

Unstable atoms or molecules containing one or more unpaired outer-shell electrons (such as the hydroxyl radical $\text{OH}^\bullet$) that cause cell damage by extracting electrons from neighboring structures.

Antioxidants

Molecules that scavenge free radicals and prevent oxidative cellular damage by donating electrons to pair with unpaired radical electrons.

Endogenous Antioxidants

Antioxidants synthesized directly within human tissues, specifically glutathione and coenzyme Q10 ($\text{CoQ10}$).

Primary Vitamin Deficiency

A state of vitamin deficiency resulting directly from inadequate dietary intake.

Secondary Vitamin Deficiency

A state of vitamin deficiency induced by malabsorption, impaired transport, increased requirement, accelerated excretion, or drug interactions.

Retinoids

A group of Vitamin A-related compounds including retinol, retinal (retinaldehyde), retinoic acid, and $\beta$-carotene.

$\beta$-Carotene

A plant-derived carotenoid pigment that serves as the most effective provitamin A precursor in the diet.

Cholecalciferol

Vitamin $\text{D}_3$, synthesized in the skin from 7-dehydrocholesterol following exposure to ultraviolet B light or obtained from animal dietary sources.

Ergocalciferol

Vitamin $\text{D}_2$, derived from plant and fungal sources by UV irradiation of ergosterol.

Rickets

A Vitamin D deficiency condition in children characterized by skeletal deformities such as bowlegs, knock-knees, pigeon breast, frontal bossing, and rib beading.

Osteomalacia

A Vitamin D deficiency disorder in adults presenting as bone softening with rheumatic pain, waddling gait, and tetany.

Tocopherols

A group of lipid-soluble antioxidants ($\alpha$, $\beta$, $\gamma$, $\delta$) that prevent peroxidation of polyunsaturated fatty acids (PUFA) in cell membranes.

Phylloquinone

Vitamin $\text{K}_1$, the naturally occurring form of Vitamin K synthesized by green plants.

Menaquinone

Vitamin $\text{K}_2$, a fat-soluble Vitamin K form produced by bacterial activity in the intestinal lumen.

Menadione

Vitamin $\text{K}_3$, a synthetic water-soluble Vitamin K derivative lacking the hydrocarbon side chain, making it biologically twice as potent on a weight basis as natural forms.

$\gamma$-Carboxyglutamic Acid (Gla)

An amino acid residue generated by Vitamin K-dependent carboxylase during the modification of glutamic acid residues in clotting factors.

Thiamine Pyrophosphate (TPP)

The active coenzyme derivative of Vitamin $\text{B}_1$, necessary for oxidative decarboxylation of pyruvate and $\alpha$-ketoacids and for transketolase reactions.

Dry Beriberi

A Vitamin $\text{B}_1$ (thiamine) deficiency clinical state characterized by nervous system involvement, including paresthesia, loss of reflexes, headache, and muscle wasting.

Wet Beriberi

A Vitamin $\text{B}_1$ (thiamine) deficiency condition dominated by cardiovascular pathology, including edema and effusions.

Thiaminase

An enzyme present in raw freshwater fish and shellfish that degrades up to $50\%$ of dietary thiamine.

Cheilosis

A clinical presentation involving painful inflammation, swelling, and cracking at the lips and corners of the mouth, caused by Vitamin $\text{B}_2$ (riboflavin) deficiency.

Pellagra

A Vitamin $\text{B}_3$ (niacin) deficiency disease characterized clinically by the classic triad of dermatitis, dementia, and diarrhea.

Pyridoxal Phosphate (PLP)

The active coenzyme form of Vitamin $\text{B}_6$, essential for amino acid transamination, glycogen phosphorylase activity, heme synthesis, and neurotransmitter generation.

Biotin

Vitamin $\text{B}_7$, a water-soluble monocarboxylic acid that acts as a essential coenzyme for carbon dioxide ($\text{CO}_2$) carboxylation and decarboxylation reactions.

Tetrahydrofolate (THFA)

The reduced active coenzyme form of Vitamin $\text{B}_9$ (folate) that serves as a single-carbon carrier required for purine, pyrimidine, and amino acid metabolism.

Neural Tube Defects (NTDs)

Congenital defects such as spina bifida, anencephaly, and encephalocoele resulting from incomplete embryonic neural tube closure due to maternal folate deficiency.

Intrinsic Factor

A glycoprotein secreted by gastric parietal cells required to bind cobalamin (Vitamin $\text{B}_{12}$) and enable its absorption in the terminal ileum.

Megaloblastic Anemia

Anemia characterized by large immature red blood cell precursors due to impaired DNA synthesis, caused by Vitamin $\text{B}_9$ or Vitamin $\text{B}_{12}$ deficiency.

Gulonolactone Oxidase

An enzyme in the uronic acid pathway that converts glucose into Vitamin C, which is genetically absent in humans.

Scurvy

A Vitamin C deficiency disease characterized by impaired collagen hydroxylation, leading to follicular hyperkeratosis, bleeding gums, loose teeth, delayed wound healing, and bruising.

Macrominerals

Essential inorganic minerals needed by adult humans in dietary amounts of at least $100\,mg/day$, including calcium, phosphorus, sodium, potassium, chloride, magnesium, and sulfur.

Trabeculae

Crystalline structures at the ends of long bones containing the exchangeable reserve pool (about $1\%$) of body calcium.

Ferrous Ion ($\text{Fe}^{2+}$)

The reduced form of iron that is soluble in water across all pH levels, superior in intestinal absorption, and forms black ferrous oxide ($\text{FeO}$).

Ferric Ion ($\text{Fe}^{3+}$)

The oxidized form of iron that is soluble in water only at pH values below $3.5$ and forms red-brown ferric oxide ($\text{Fe}_2\text{O}_3$).

Divalent Metal Transporter 1 (DMT1)

An intestinal apical membrane transport protein that transfers non-heme ferrous iron ($\text{Fe}^{2+}$) from the intestinal lumen into enterocytes.

Ferritin

A intracellular protein-iron complex that stores ferric iron ($\text{Fe}^{3+}$) in a readily mobilizable state within tissues.

Metallothionein

The most abundant non-enzymatic zinc- and copper-binding protein in cells, functioning in metal detoxification and mineral storage.

Ceruloplasmin

A plasma copper-containing protein that converts ferrous iron ($\text{Fe}^{2+}$) to ferric iron ($\text{Fe}^{3+}$) for binding and transport by transferrin.

Fluoroapatite

A mineral compound created when fluoride replaces hydroxyl groups in dental enamel calcium phosphate salts, conferring heightened resistance against acid erosion and caries.

Thyroglobulin

A thyroid follicular protein matrix containing tyrosine residues that bind iodine during the biosynthesis of thyroid hormones ($\text{T}_3$ and $\text{T}_4$).

Glutathione Peroxidase

A selenium-dependent enzyme containing selenocysteine that detoxifies cellular hydroperoxides into water and organic alcohols.