Water, pH, Carbohydrates, Lipids & Protein Structure – Review Flashcards

Fill-in-the-blank flashcards covering key principles of water chemistry, buffering and pH, carbohydrate and lipid classification and function, protein structure and folding, and collagen-related clinical correlations.

Water’s exceptionally high dielectric constant at 25 °C is approximately .

78.5

On average, each liquid‐water molecule forms hydrogen bonds with about other water molecules.

3.5

Hydrophobic interaction refers to the tendency of compounds to self-associate in water.

non-polar

Electrostatic interactions between oppositely charged groups in biomolecules are called .

salt bridges

The force of van der Waals interactions decreases with the power of the distance between atoms.

sixth

Water is an excellent because its lone pairs can attack electron-poor atoms.

nucleophile

The ion product of water (Kw) at 25 °C equals (mol/L)^2.

1.0 × 10⁻¹⁴

pH is defined as the negative logarithm of the concentration.

hydrogen-ion (H⁺)

When a weak acid is half-neutralized, pH equals its .

pKa

Buffers are most effective within ± pH unit of their pKa.

1

Glucose is classified chemically as an hexose.

aldo

Monosaccharides that rotate plane-polarized light to the right are designated .

dextrorotatory (+)

The ring form of glucose that resembles a six-membered pyran ring is called .

glucopyranose

Isomers differing only at the anomeric carbon are called .

α- and β-anomers

Mannose is the C-2 of glucose.

epimer

Lactose is composed of glucose linked to .

galactose

Amylose consists of glucose units connected solely by glycosidic bonds.

α-1,4

Glycogen branches are formed through glycosidic linkages.

α-1,6

Dietary polysaccharides not digested by human enzymes constitute .

dietary fiber (non-starch polysaccharides)

Glycosaminoglycans are heteropolysaccharides containing amino sugars and acids.

uronic

The glycemic index ranks foods by how strongly they raise levels.

blood glucose

Lipids are defined operationally by their solubility in solvents.

non-polar (e.g., ether, chloroform)

Fatty acids with no double bonds are termed .

saturated

Naturally occurring unsaturated fatty acids almost always have double bonds in the configuration.

cis

The first carbon atom next to the carboxyl carbon is designated the carbon.

α

Omega-3 (ω-3) fatty acids exert effects by altering eicosanoid synthesis.

anti-inflammatory

Triacylglycerols are esters of glycerol with fatty acids.

three

Phosphatidylcholine is commonly known as .

lecithin

Sphingomyelin contains the amino alcohol instead of glycerol.

sphingosine

The basic four-ring nucleus common to all steroids is called the nucleus.

cyclopentanoperhydrophenanthrene

Auto-oxidation of unsaturated lipids in air is termed lipid .

peroxidation

Vitamin E functions primarily as a antioxidant in membranes.

chain-breaking

The linear sequence of amino acids in a protein describes its structure.

primary

Regular repeating patterns stabilized by backbone hydrogen bonds define the structure of proteins.

secondary

An α-helix has hydrogen bonds between the carbonyl of residue i and the amide of residue .

i + 4

β-Strands hydrogen-bond laterally to form .

β-sheets

The overall three-dimensional folding of a single polypeptide is its structure.

tertiary

The spatial arrangement of multiple polypeptide subunits constitutes structure.

quaternary

Protein folding in vivo is often assisted by specialized proteins called .

molecular chaperones

Misfolding and aggregation of amyloid-β peptide are central to disease.

Alzheimer

The repeating unit of mature collagen is known as .

tropocollagen

Every third residue in collagen is , allowing tight packing of the triple helix.

glycine

Hydroxylation of proline and lysine in collagen requires vitamin .

C (ascorbic acid)

Defective collagen cross-linking due to copper deficiency leads to disease.

Menkes

Blue sclera and brittle bones are characteristic of imperfecta.

osteogenesis

Salt bridges, hydrophobic interactions, hydrogen bonds, and forces stabilize protein tertiary structure.

van der Waals

According to Coulomb’s law, the strength of charge interactions is inversely proportional to the of the medium.

dielectric constant

Self-association of amphipathic molecules into micelles is driven by the surrounding molecules.

water

Using the Henderson-Hasselbalch equation, pH = pKa + log([A⁻]/[]).

HA

A weak acid–conjugate base pair that resists pH change is called a .

buffer

Carboxyl groups typically have pKa values around .

4–5

Amino groups on free amino acids have pKa values near .

9–10

Addition of ethanol lowers the dielectric constant of water and therefore the pKa of amines.

decreases

Hydrogen bonds in liquid water have a half-life measured in seconds.

pico

The strength of a single hydrogen bond in water is roughly kcal/mol.

4.5

Non-polar molecules tend to aggregate in water to minimize the decrease in system .

entropy

Phosphatidylinositol derivatives act as key mediators in cell pathways.

signaling

Plasmalogens constitute up to 30 % of the phospholipids in tissue.

brain (and heart)

In β-turns of proteins, the amino acids and glycine are commonly found.

proline

The collapse of hydrophobic residues during early protein folding is termed collapse.

hydrophobic

The disease-causing form of the prion protein is rich in -sheet structure.

β

In triacylglycerols, carbons 1 and 3 of glycerol are stereochemically .

non-identical (prochiral)

The omega carbon in a fatty acid is the methyl carbon.

terminal (ω or n)

Fatty-acid melting point as chain length increases and with unsaturation.

increases; decreases

Industrial partial hydrogenation of vegetable oils produces harmful fatty acids.

trans

Cholesterol in membranes helps to modulate membrane .

fluidity

Dolichol phosphate functions as a carrier of in glycoprotein synthesis.

oligosaccharides