Chapter 11

These flashcards cover the major concepts of lipids, their structures, functions, and health implications, based on lecture notes.

What are lipids?

A large, heterogeneous population of water-insoluble biological molecules that are highly soluble in organic solvents.

What roles do lipids play in biological systems?

They store energy, are key components of membranes, and play roles in signal-transduction pathways.

Do lipids form polymers?

No, lipids do not form polymers; they form noncovalent assemblies.

What is a free fatty acid?

A fatty acid that is not esterified to another molecule and has a hydrocarbon chain with a carboxylic acid group.

What does amphipathic mean in relation to lipids?

Amphipathic lipids have both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts.

What is the significance of phosphatidate?

It is the simplest phosphoglyceride and a key intermediate in the biosynthesis of other phosphoglycerides and triacylglycerols.

What is a triacylglycerol?

A lipid formed from the esterification of three fatty acids to glycerol.

How does a fatty acid's degree of unsaturation affect its properties?

Unsaturated fatty acids have lower melting points than saturated fatty acids of the same length.

What is the difference between saturated and unsaturated fatty acids?

Saturated fatty acids have only single bonds; unsaturated fatty acids have one or more double bonds.

What does the shorthand notation 16:1 mean?

It denotes a fatty acid with 16 carbon atoms and one double bond.

What is a cerebroside?

The simplest glycolipid containing a single sugar residue attached to sphingosine.

What role do eicosanoid hormones play in the body?

They are signaling molecules that alter the activities of the cells in which they are synthesized.

What is the impact of trans-unsaturated fats on health?

They are correlated with high cholesterol levels and cardiovascular disease.

What are triacylglycerols primarily used for in the body?

They are used for energy storage.

What are steroids?

Lipids that function as hormones and are key components of cell membranes.

What is cholesterol's function in biological membranes?

It maintains membrane fluidity.

What is a glycosphingolipid?

A lipid composed of a sphingosine backbone, fatty acid, and sugar residues.

What happens to fatty acids during esterification?

They form ester linkages with glycerol or other alcohols, resulting in triacylglycerols.

How does the structure of sphingolipids differ from phospholipids?

Sphingolipids contain sphingosine as their backbone, whereas phospholipids typically have glycerol.

What is the significance of omega-3 fatty acids?

They are essential fatty acids that play a role in protecting against cardiovascular disease.

What are the effects of cis double bonds in fatty acids?

They introduce kinks in the fatty acid chains, preventing tight packing and reducing melting temperature.

What are some common examples of saturated fatty acids?

Stearic acid, palmitic acid, and myristic acid.

What is a phospholipid?

A lipid molecule with a hydrophilic head and two hydrophobic tails, critical for cell membranes.

What are lipid rafts?

Microdomains in cell membranes rich in sphingolipids and cholesterol that play important roles in signaling.

Where are triacylglycerols primarily stored in the body?

In adipose tissue.

What are the two types of unsaturated fatty acids?

Monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs).

What effect does the chain length of fatty acids have on melting points?

Longer-chain fatty acids typically have higher melting points.

What is Niemann–Pick disease?

A lipid storage disorder resulting from an accumulation of sphingomyelin.

What is the primary structural difference between triacylglycerols and phospholipids?

Triacylglycerols have three fatty acids attached to glycerol, while phospholipids have two fatty acids and a phosphate group.

What is a biological wax?

Waxes are long-chain fatty acids esterified to long-chain alcohols, used for protective coatings.

How do fatty acids contribute to the energy density of lipids?

Fatty acids are richer in energy than carbohydrates and are stored in a compact, hydrophobic form.

What is the physiological importance of understanding lipid metabolism?

It is crucial for preventing and treating diseases related to lipid imbalances, such as cardiovascular diseases.

What is the primary function of sphingomyelin?

It is important for the structure and function of cell membranes, especially in nerve cells.

What is the general structure of steroids?

Steroids consist of a tetracyclic ring structure known as the steroid nucleus.

What does the term 'amphipathic' imply?

The molecule has both hydrophobic and hydrophilic parts, allowing it to form structures like bilayers.

What defines a phospholipid bilayer's asymmetry?

The sugar residues of glycolipids are oriented towards the extracellular environment or luminal side.

What promotes the formation of lipid rafts?

The presence of sphingolipids and cholesterol in certain regions of the membrane.

What are the health implications of high saturated fat consumption?

It is correlated with increased cholesterol levels and heightened risk of cardiovascular disease.

What enzyme is crucial in fire-related conditions like Niemann–Pick disease?

Sphingomyelinase, which degrades sphingomyelin.

How does the structure of eicosanoids relate to their function?

They are derived from fatty acids and have roles in local signaling and inflammation.

What type of bond connects fatty acids to glycerol in triacylglycerols?

Ester bonds.

What do arachidonic acid derivatives primarily function as?

Precursors to eicosanoid signaling molecules.

What are the potential consequences of improper farnesylation?

Can lead to Hutchinson–Gilford progeria syndrome, causing premature aging.

How does increased unsaturation affect membrane fluidity?

Increases fluidity due to less tight packing of lipid tails.

What is the primary storage form of lipids in the body?

Triacylglycerols.

What is the function of lipoproteins in lipid transport?

They transport lipids through the bloodstream to various tissues.

What characteristic of membrane lipids facilitates cell recognition?

Glycolipids present on the extracellular surface play key roles in cell-cell interactions.

What defines the structure of a phosphoglyceride?

It has a glycerol backbone, two fatty acids, and a phosphorylated alcohol.

What type of fatty acids are essential for human health?

Certain polyunsaturated fatty acids like omega-3 and omega-6 fatty acids.

What impact does chain length have on fatty acid solubility?

Longer chains typically lead to lower solubility in aqueous environments.

What is the role of enzymes in lipid metabolism?

They facilitate the synthesis and degradation of lipids.

What is an important feature of ether lipids found in archaea membranes?

They have ether linkages that are resistant to hydrolysis.

What role does cholesterol play in membranes?

It modulates membrane fluidity, making membranes flexible yet stable.

What is the precursor to all steroid hormones?

Cholesterol.

What happens during the process of lipid hydrolysis?

Fatty acids are released from triacylglycerols into the bloodstream for use as energy.

What key process occurs in animal fat metabolism?

Conversion of triacylglycerols to free fatty acids for use in energy.

What is the structural basis for the action of lipid-based drugs?

Their ability to interact with cell membranes and target specific receptors.

How do cells utilize glycolipids?

For energy storage and as components of cell membranes enhancing cell recognition.

What is the significance of amphipathic properties in biological molecules?

They allow the formation of membranes and micelles that are crucial for cellular function.

What is a significant outcome of the lipid bilayer's asymmetry?

It contributes to the specific functions of membranes, including signaling and transport.

What are the consequences of excess lipid accumulation in cells?

Can lead to metabolic disorders and diseases such as obesity.

What is the primary storage lipid in humans?

Triacylglycerol.

How do sphingolipids differ in function compared to traditional phospholipids?

Sphingolipids are involved in signaling and forming lipid rafts.

What type of bond links sugars to sphingolipids?

Glycosidic bonds.

What type of signaling do eicosanoids engage in?

They act as local hormones affecting nearby cells.

What role does membrane fluidity play in cell function?

It is critical for membrane protein movement and function.

What are omega-6 fatty acids and their significance?

They are essential fatty acids involved in inflammatory response.

How do enzymes regulate lipid metabolism?

By facilitating the breakdown and synthesis of lipid compounds.