Biochemistry of Lipids Quiz

Lipids are organic molecules that are insoluble in water but readily dissolve in non-polar solvents like chloroform or ether. They are characterized by their hydrocarbon chains and ester groups.

Lipids are broadly categorized into simple and complex lipids. Simple lipids consist of fatty acids combined with alcohols, like triglycerides, while complex lipids contain additional components like phosphate groups or nitrogenous compounds.

Fatty acids are long hydrocarbon chains with a carboxyl group at one end. Most natural fatty acids have an even number of carbons and are unbranched.

Saturated fatty acids have no double bonds in their hydrocarbon chain, meaning they are 'saturated' with hydrogen atoms. They tend to be solid at room temperature.

Monounsaturated fatty acids have one double bond in their hydrocarbon chain, causing a kink in the molecule, which generally makes them liquid at room temperature.

Polyunsaturated fatty acids have multiple double bonds within their hydrocarbon chain making them even more fluid. They are typically liquid at room temperature.

The simplest way to represent a fatty acid is by writing its chain length and the number of double bonds separated by a colon. For example, palmitic acid (16 carbons, saturated) is written as 16:0.

The position of double bonds in a fatty acid is denoted with a delta (Δ) followed by a superscript number referring to the carbon atom involved. For example, oleic acid with a double bond between C-9 and C-10 is written as 18:1(Δ9).

A type of lipid where one of the fatty acid chains is attached to glycerol through an ether linkage instead of the usual ester linkage. This makes the molecule more resistant to chemical breakdown.

An ether lipid that acts as a potent signaling molecule, released from cells called basophils. It triggers platelet aggregation, promotes serotonin release, and plays a role in inflammation and allergies.

The structural backbone of sphingolipids, a long-chain amino alcohol that forms the foundation for this class of lipids.

A type of sphingolipid made up of ceramide and phosphocholine. It's found in the myelin sheath that surrounds some nerve cells, acting as an insulator for nerve impulses.

Glycolipids that predominantly occur in plants. They are made up of diacylglycerol with one or two galactose residues attached.

The process of adding hydrogen to unsaturated fats, converting them into more stable saturated or partially saturated fats. This increases stability, reduces rancidity and extends shelf life.

Triacylglycerols are fats that are stored in cells as energy reserves. They are mainly composed of three fatty acids linked to a glycerol molecule.

Vegetable oils are liquid at room temperature because they are mainly composed of triacylglycerols with unsaturated fatty acids. These fatty acids have kinks in their chains, preventing close packing and making the oil liquid.

Triacylglycerols are stored in cells as microscopic oily droplets, providing a fuel depot. Adipocytes (fat cells) are specialized for storing large amounts of triacylglycerols.

Partial hydrogenation converts liquid unsaturated fats into more solid fats, making them more stable and extending their shelf life. This process is often used for cooking oils, but can produce trans fats.

The process of partial hydrogenation can change the structure of fatty acids, leading to the formation of trans fats. Trans fats have been linked to increased risk of heart disease.

Plant seeds store triacylglycerols as energy reserves for germination. This provides energy and building blocks for new growth.

A class of lipids composed of glycerol, two fatty acids, and a polar head group. The head group is connected to glycerol via a phosphodiester bond and can have various charges affecting membrane properties.

Glycerol, initially a prochiral molecule, becomes chiral when a phosphate group attaches to its third carbon. This change in chirality allows for different naming conventions like L-glycerol 3-phosphate, D-glycerol 1-phosphate, or sn-glycerol 3-phosphate.

The polar head group in glycerophospholipids determines their function and properties, influencing membrane interactions and overall behavior. This head group can be negatively charged (e.g., phosphatidylinositol 4,5-bisphosphate), neutral (e.g., phosphatidylserine), or positively charged (e.g., phosphatidylcholine, phosphatidylethanolamine).

A two-tailed glycerophospholipid where two phosphatidic acid moieties share the same glycerol as their head group. It is crucial for bacterial membranes and the inner mitochondrial membrane of eukaryotic cells, supporting the endosymbiotic theory of mitochondria origin.

Cardiolipin's prevalence in bacterial membranes and the inner mitochondrial membrane of eukaryotes supports the endosymbiotic hypothesis. This hypothesis suggests that mitochondria originated from ancient prokaryotic cells that were engulfed by eukaryotic cells.

The major component of most eukaryotic cell membranes. It's a type of glycerophospholipid with a positively charged choline head group.

Many prokaryotes, including E. coli, cannot synthesize phosphatidylcholine and their membranes do not contain it. This indicates differences in membrane composition between prokaryotes and eukaryotes.

A phosphodiester bond links the head group to glycerol in glycerophospholipids. This bond plays a key role in determining the properties and interactions of the lipid.

Sphingolipids are a class of lipids found in the membranes of eukaryotic cells, especially abundant in neurons. They have a unique structure consisting of a sphingosine backbone, a fatty acid chain, and a polar head group.

Glycosphingolipids are a type of sphingolipid with a carbohydrate head group attached to the sphingosine backbone. These carbohydrates can be simple or complex sugars, and they play a crucial role in cell recognition and adhesion.

The ABO blood groups are determined in part by the specific oligosaccharide head groups present on glycosphingolipids. These differences in sugar chains affect how our bodies recognize and interact with blood cells.

Lipids in cell membranes are constantly being degraded and replaced. This process is essential for maintaining membrane fluidity and function. Phospholipases are enzymes that break down phospholipids, while specific enzymes degrade gangliosides.

Lipid anchors are special molecules that attach proteins to cell membranes. These anchors can be fatty acids, isoprenoids, sterols, or glycosylated phosphatidylinositol. They allow proteins to be anchored to the membrane, either reversibly or irreversibly.

Sterols are a class of lipids that are important for membrane structure and function. They have a distinctive rigid structure consisting of four fused rings, with variations in their side chains. Cholesterol is the most common sterol in animal cells.

Cholesterol is a major sterol in animal cells. It's amphipathic, meaning it has both a polar head and a nonpolar tail, which allows it to interact with both the hydrophilic and hydrophobic parts of the membrane. Cholesterol plays a role in membrane fluidity and stability.

Sterols serve as precursors for a variety of biologically active molecules, including steroid hormones, bile acids, and vitamin D. Steroid hormones regulate gene expression, while bile acids emulsify fats in the digestive system.

A class of lipids that contain one molecule of the long-chain amino alcohol sphingosine or one of its derivatives. They typically have a polar head group and two nonpolar tails.

A type of glycosphingolipid that contains a single monosaccharide linked to ceramide. They can be found in the plasma membranes of cells in neural tissue and nonneural tissues.

A type of glycosphingolipid that has a polar head group consisting of oligosaccharides, including at least one residue of N-acetylneuraminic acid (Neu5Ac), a type of sialic acid.

A type of glycosphingolipid with two or more sugars linked to ceramide. They often contain D-glucose, D-galactose, or N-acetyl-D-galactosamine, and are considered neutral glycolipids due to their lack of charge at pH 7.

A genetic disorder resulting from a deficiency in the enzyme that breaks down gangliosides, leading to their accumulation in the brain, causing severe neurological damage.

The blood groups are determined by the specific sugars present on the head groups of glycosphingolipids. Different glycosyltransferases dictate the type of sugar added.