Lipids and Cell Membranes lect 8

Vocabulary flashcards covering lipids, fatty acids, steroids, and cell membrane structure and function.

Lipids

Biomolecules found in fats, waxes, steroids, many vitamins, diglycerides, glycerides, and phospholipids; everything that isn't amino acids, peptides, proteins, ions, carbohydrates, DNA, and RNA.

Fatty Acids

Long hydrocarbon chains with a carboxylic acid head group, generally ionized in solution; hydrophobic and hydrophilic properties allow for self-assembling.

Saturated Fatty Acids

Fatty acids without any double bonds; generally considered bad dietary fats and typically found in butter/solid fats.

Unsaturated Fatty Acids

Fatty acids with double bonds (cis or trans); generally considered good dietary fats (if not trans) and typically found in margarine/liquid or soft fats.

Monounsaturated Fatty Acids

Fatty acids with one double bond.

Polyunsaturated Fatty Acids

Fatty acids with multiple double bonds.

pKa of Fatty Acids

Typically around 4 to 5; body acidity is around 6 to 7, which means fatty acids are mostly ionized (minus form) in the body, making them chemically reactive.

Glycerides

Compound esters of glycerol and fatty acids; industrially important for isolating fatty acids. Can be monoglycerides (one ester group), diglycerides (two ester groups), or triglycerides (three ester groups).

Phospholipids

Glycerol molecule with two ester groups and a phosphate group on the upper position; can have various additions on the other side of the phosphate (ethanolamine, choline, serine, inositol).

Sphingolipids

Phospholipids connected by amide bonds instead of ester bonds.

Steroids

Lipids with a cyclic skeleton (cyclohexanes and cyclopentanes); stereochemistry defines their shape, which helps them interact with enzymes and receptors.

Hormones

Steroids that act in the regulation of physiological activities and homeostasis; chemical messengers (e.g., cholesterol, testosterone, hydrocortisone).

Membrane Lipids

Mainly made of lipids with long hydrocarbon tails, glycerol group attached to phosphate, and phosphate attached to various things (e.g., choline); typically have a double bond in one of the chains.

Lateral Diffusion

The constant movement of molecules within the lipid bilayer membrane.

Cholesterol's Influence

A direct influencer on the relative fluidity of the membrane; more cholesterol means less fluidity.

Glycolipids

Formed when carbohydrates attach to lipids.

Glycoproteins

Formed when carbohydrates attach to proteins.