Lecture Notes - Essential Molecules I, Water Physics, Lipids, Membranes

Flashcards covering how water behaves, solubility, oxygen roles, dehydration/hydrolysis, and lipid/membrane structure and function.

Cohesion

Water molecules sticking to each other via hydrogen bonding and polarity, contributing to surface tension.

Adhesion

Water molecules sticking to other surfaces due to polarity, aiding capillary action and tree/plant movement.

Polarity

Unequal sharing of electrons in a bond that creates partial charges and enables hydrogen bonding.

Hydrogen bond

An electrostatic attraction between partial charges on adjacent molecules, not a true covalent bond.

Surface tension

The cohesive force at the surface of a liquid that makes water behave as if its surface is covered with a stretched membrane.

Hydrophilic

Describes substances that interact well with water due to charges or polar groups; water-soluble.

Hydrophobic

Describes substances that repel water due to nonpolar characteristics or few charges.

Solvent

A substance (often water) that dissolves solutes.

Solute

A substance dissolved in a solvent.

NaCl dissolution

Salt dissolves in water as Na+ and Cl− ions are attracted by water's partial charges.

Ion

An atom or molecule with a net electric charge.

Cation

Positively charged ion.

Anion

Negatively charged ion.

Oxygen as fuel

Oxygen is used to oxidize nutrients to produce ATP in cells.

Oxygen as oxidant

Oxygen accepts electrons during metabolism, releasing energy as ATP.

Reactive oxygen species

Reactive forms of oxygen that can damage cells if not regulated.

Antioxidants

Molecules that regulate oxidants and protect cells from oxidative damage.

Vitamin C

Water-soluble vitamin; supports immune function; deficiency can cause gum bleeding.

Vitamin D2

Fat-soluble vitamin; precursor to steroid hormones; interacts with membranes.

Vitamin E

Fat-soluble antioxidant vitamin protecting lipids in membranes from oxidation.

Oxygen solubility in water

O2 dissolves poorly in water because it is nonpolar; requires continual replenishment.

Carbon vs. Oxygen electron sharing

Carbon shares electrons more evenly (less polar) than oxygen, which pulls electrons toward itself (more polar).

Dehydration synthesis

Builds polymers by removing water; monomers join and release a water molecule.

Hydrolysis

Breaks polymers by adding water; water is consumed to split monomers.

Monomer

A small building block that links to form a polymer.

Polymer

A large molecule formed from many monomers.

Lipids

A diverse group of hydrophobic molecules (fats, phospholipids, steroids) rich in C–H bonds.

Triglyceride

Fat formed from glycerol plus three fatty acids; primary long-term energy store.

Glycerol

Three-carbon backbone to which fatty acids (and phosphate) attach in lipids.

Fatty acid

Hydrocarbon chain that can be saturated (no double bonds) or unsaturated (one or more double bonds).

Saturated fat

Fatty acids with no C=C double bonds; typically solid at room temperature; higher energy density.

Unsaturated fat

Fatty acids with one or more C=C double bonds; kinked tails; typically liquid at room temperature.

Polyunsaturated fat

Fatty acids with two or more double bonds; includes omega-6 and omega-3 fatty acids.

Prostaglandins

PUFAs that regulate inflammation, clotting, and wound healing; omega-6 vs omega-3 derivatives differ in effect.

Omega-6

PUFA that tends to promote pro-inflammatory prostaglandins; imbalance with omega-3 can affect health.

Omega-3

PUFA that tends to promote anti-inflammatory prostaglandins; supports immune balance.

Phospholipid

Amphipathic lipid with glycerol, a phosphate head (polar) and two fatty acid tails (nonpolar); forms membranes.

Bilayer

Two-layer arrangement of phospholipids that forms cell membranes and protects interior.

Membrane fluidity

The ease of movement of lipids and proteins within the membrane; influenced by temperature and unsaturation.

Membrane proteins

Proteins embedded in the lipid bilayer that enable selective transport and other functions.

Selective permeability

Membrane property that allows some substances to cross while blocking others.

Cholesterol

Sterol that modulates membrane fluidity and serves as a precursor to steroid hormones.

Steroids

Lipids with four fused carbon rings and no fatty acid tails; include hormone steroids.

Phospholipids vs fats

Phospholipids form membranes with a polar head and nonpolar tails; fats (triglycerides) are energy-rich and hydrophobic.

Water-soluble vitamins

Vitamins that dissolve in water (e.g., Vitamin C) and are readily excreted.

Fat-soluble vitamins

Vitamins that dissolve in fats (e.g., Vitamins D2 and E) and are stored in body fat.