Your Sets

What is the defining property of biological lipids?

They are amphipathic: they contain hydrophilic and hydrophobic regions.

What is a fatty acid?

A long hydrocarbon (alkyl) chain ending in a carboxylic acid group; numbering starts at the COOH end.

What does saturated fatty acid mean?

Its carbon chain has no carbon-carbon double bonds and is saturated with hydrogen.

What does unsaturated fatty acid mean?

It contains one or more carbon-carbon double bonds.

What configuration are most naturally occurring unsaturated fatty-acid double bonds?

Cis.

What effect does a cis double bond have on a fatty-acid chain?

It introduces a kink, reducing how tightly chains pack.

How does increasing cis double-bond number affect melting point?

More cis double bonds → poorer packing → lower melting point.

Why do saturated fatty acids generally have higher melting points than cis-unsaturated fatty acids?

Their straighter chains pack more tightly, increasing intermolecular van der Waals interactions.

How do trans fatty acids compare structurally to saturated fatty acids?

They are straighter and resemble saturated fatty acids more than cis-unsaturated fatty acids.

How can trans fats be formed?

By bacterial synthesis or partial hydrogenation.

What health effect of trans fats is emphasized in the slides?

They can alter membrane composition and increase LDL, contributing to coronary artery disease.

What does fatty-acid notation 16:1 Δ9 mean?

16 carbons, one double bond beginning at carbon 9 (counting from the carboxyl end).

What is alpha-linolenic acid also called?

9,12,15-octadecatrienoic acid; an omega-3 fatty acid.

What is gamma-linolenic acid also called?

6,9,12-octadecatrienoic acid; an omega-6 fatty acid.

What is linoleic acid?

An essential omega-6 fatty acid with 18 carbons and double bonds at Δ9 and Δ12 (18:2).

What is alpha-linolenic acid?

An essential omega-3 fatty acid with 18 carbons and double bonds at Δ9, Δ12, and Δ15 (18:3).

What is arachidonic acid?

A 20-carbon omega-6 fatty acid with four double bonds at Δ5, Δ8, Δ11, and Δ14.

How can the body make arachidonic acid?

Through multistep enzymatic modification of linoleic acid.

What does omega nomenclature count from?

The methyl (terminal) end of the fatty-acid chain.

What is a triacylglycerol (triglyceride)?

Glycerol esterified to three fatty acids.

What is a major function of triacylglycerols?

Energy storage and supply.

Why are fatty acids energy-dense compared with carbohydrates?

They are more reduced and yield more energy upon oxidation; slides state about 38 kJ/g vs ~17 kJ/g for carbohydrates.

What does beta-oxidation yield for every two carbons removed, according to the slides?

One acetyl-CoA, one NADH, and one FADH2.

Where does fat absorption occur, according to the slides?

In the intestinal lining.

What are glycerophospholipids built from?

A glycerol backbone, two fatty-acyl chains, phosphate, and a head group.

At which glycerol position does phosphorylation occur in glycerophospholipids?

C3.

How are glycerophospholipids numbered?

Glycerol positions are C1, C2, and C3; phosphate is attached at C3.

How do glycerophospholipids vary from one another?

By their phosphate-containing head group and/or fatty-acyl chains.

What common fatty-acyl pattern is noted for phosphatides?

C1 is often saturated and C2 is often unsaturated, causing a kink.

What does adding phosphate do to a glycerol lipid's amphipathic character?

It increases the polar/hydrophilic character.

What is an ether glycerophospholipid?

A glycerophospholipid with an ether linkage at glycerol C1 instead of the usual ester linkage.

What is platelet-activating factor (PAF)?

A common ether glycerophospholipid with a short acetate acyl chain at C2; it activates white blood cells in inflammation and supports platelet aggregation.

What is a plasmalogen?

An ether glycerophospholipid with an unsaturation at C1; common in nervous and cardiovascular tissues.

What roles do plasmalogens have?

Cellular insulation/protection against reactive oxygen species and potential signaling roles.

What is the backbone of sphingolipids?

An 18-carbon alcohol backbone called sphingosine.

How does sphingomyelin differ from glycerophospholipids?

It uses a sphingosine backbone and an amide-linked fatty acid; it has a phosphocholine head group.

Where is sphingomyelin especially important?

The myelin sheath, which insulates nerve impulses.

What are lipid rafts?

Membrane microdomains often rich in glycosylated sphingolipids and cholesterol that organize/transport complexes.

What are glycosphingolipids?

Sphingolipids with carbohydrate head groups.

What are cerebrosides?

Glycosphingolipids with a simple sugar head group.

What are gangliosides?

Glycosphingolipids with more complex sugar head groups, commonly including sialic acid.

What is a key function of glycosphingolipids?

Cell-cell recognition; they are also present at nerve endings and support nerve impulses.

What causes Tay-Sachs disease in the slides?

Hexosaminidase A (HexA) deficiency, leading to a lysosomal storage disorder.

What are waxes made of?

Long-chain alcohols esterified to long-chain fatty acids.

What is a function of plant waxes?

Prevent water loss and waterlogging.

What is beeswax's function?

A major component of hives; it makes them pliable and water-resistant.

What are terpenes (isoprenoids)?

Lipids formed by combinations of isoprene units.

What is an isoprene unit?

A five-carbon unit (2-methyl-1,3-butadiene).

How are terpene classes grouped by isoprene-unit count?

Monoterpenes: 2 units; sesquiterpenes: 3; diterpenes: 4; triterpenes: 6.

What are common roles of monoterpenes and sesquiterpenes?

Characteristic odors and flavors; some have herbaceous smells.

What kinds of molecules can be diterpenes?

Examples in the slides include plant pigments, visual pigments, and plant hormones.

What is a steroid structurally?

An isoprene-based/polyprenyl lipid built on four fused rings.

What is the most common animal sterol?

Cholesterol.

What are bile acids?

Amphipathic steroid derivatives that aid lipid digestion.

What do plant sterols do in the slides?

Act as cholesterol mimics and prevent cholesterol uptake.

What are steroid hormones used for biologically?

Signaling, including regulation of pregnancy/menstruation, metabolism, and stress.

What is cholesterol a precursor for?

Steroid hormones and other cholesterol-derived molecules.

What type of lipid is useful for regulating sexual function?

Steroid hormones.

What type of lipid helps protect organisms from dehydration?

Waxes.

What type of lipid provides energy storage?

Triacylglycerols.

What type of lipid is a major structural membrane component?

Phospholipids and sphingolipids.

What are biological lipid signals generally like?

They act locally, trigger cascades, have short lifetimes, and are carefully regulated in synthesis and breakdown.

What is a phospholipase?

An enzyme that cleaves phospholipids with high substrate/bond specificity.

Where does phospholipase A1 cleave a glycerophospholipid?

At the ester bond of the fatty acid at glycerol C1 (sn-1).

Where does phospholipase A2 cleave a glycerophospholipid?

At the ester bond of the fatty acid at glycerol C2 (sn-2).

Where does phospholipase C cleave a phospholipid?

Between glycerol and phosphate, releasing a diacylglycerol (DAG) and a phosphorylated head group.

Where does phospholipase D cleave a phospholipid?

Between phosphate and the head group, leaving phosphatidic acid and releasing the head group.

What does phospholipase B do?

Removes fatty-acyl chains from both sn-1 and sn-2 positions (often acts on lysophospholipids as well).

If a phospholipid has alpha-linolenic acid at C2, which phospholipase releases it as a free fatty acid?

Phospholipase A2.

What are common consequences of phospholipid breakdown in signaling?

It can produce signaling molecules that affect inflammation, cell division, neuronal signaling, and kinase cascades.

What is the IP3 pathway associated with?

Phospholipid-derived secondary messenger signaling.

What is sphingosine-1-phosphate (S1P)?

A phosphorylated sphingosine lipid signal that can act inside cells or be exported for extracellular signaling.

What effects can S1P signaling have, according to the slides?

It can trigger inflammatory or allergic responses and affect diverse cellular processes.

What is the general difference between triglycerides and phospholipids?

Triglycerides have three fatty acids and mainly store energy; phospholipids have two fatty acids plus a polar head group and form membranes.

What is the general difference between glycerophospholipids and sphingolipids?

Glycerophospholipids use glycerol; sphingolipids use sphingosine as the backbone.

What is the general difference between phospholipids and glycolipids?

Phospholipids have a phosphate-containing head group; glycolipids have carbohydrate head groups.

Why are lipids amphipathic important for membranes?

Their polar heads interact with water while hydrophobic tails avoid water, supporting membrane organization.

How does cis unsaturation affect lipid bilayer fluidity?

Kinks hinder tight packing, generally increasing fluidity.

Which fatty acid is 18:0?

Stearic acid.

Which fatty acid is 16:0?

Palmitic acid.

Which fatty acid is 18:1 Δ9 cis?

Oleic acid.

Which fatty acid is 18:2 Δ9,12?

Linoleic acid.

Which fatty acid is 18:3 Δ9,12,15?

Alpha-linolenic acid.

Which fatty acid is 20:4 Δ5,8,11,14?

Arachidonic acid.