Biochemistry of Lipids, Membranes, and Carbohydrates (Chapters 1-8)

A set of QA-style flashcards covering key lipid, membrane, and carbohydrate concepts from the lecture notes.

What is the process of breaking the double bonds in fatty acids to make them more like saturated fats, often resulting in solids at room temperature, called?

Hydrogenation.

What reaction, base-catalyzed, produces a soap salt when fatty acids are treated with a base?

Base-catalyzed ester hydrolysis (saponification) producing a soap salt.

What structure is formed when phospholipids organize into a bilayer with hydrophilic heads facing water on both sides?

A liposome (phospholipid bilayer vesicle with an aqueous interior).

Glycolipids are sugars attached to lipids found prominently in which systems, and what is their role?

Found in membranes (including the brain); involved in cell recognition and self-marking.

What are the three types of eicosanoids derived from arachidonic acid?

Prostaglandins, leukotrienes, and thromboxanes.

What is the role of cholesterol in membranes?

Provides rigidity to the membrane and helps modulate fluidity by intercalating between lipid tails.

What is the four-ring carbon skeleton called, and which molecule in membranes is a sterol derived from this skeleton?

The four-ring skeleton is a steroid; cholesterol is a sterol derived from it.

What is the functional difference between a sterol and a steroid in the context of membranes?

Steroid refers to the four-ring skeleton; cholesterol is a sterol (a steroid with a hydroxyl group) that modulates membrane properties.

What structure do phospholipids form in membranes, and why is this arrangement important?

A lipid bilayer with tails facing each other, creating a hydrophobic interior and a hydrophilic exterior, critical for selective permeability.

What is the role of prostaglandins in the body?

Involved in pain signaling and smooth muscle relaxation/dilation; also used to induce labor via cervical ripening.

What is the role of thromboxanes in the body?

Involved in platelet aggregation and blood clot formation.

What is the role of leukotrienes in inflammation?

Involved in inflammatory responses and bronchoconstriction (relevant to asthma).

How does the body transport cholesterol in the blood, and why is LDL often called 'bad' cholesterol while HDL is called 'good' cholesterol?

Cholesterol is carried by lipoproteins. LDL transports cholesterol to tissues (risk factor when high); HDL scavenges cholesterol esters and transports them to the liver for disposal (good).

Name and describe the four main lipoproteins and their general roles.

Chylomicrons VLDL, LDL, and HDL

What is the function of Chylomicrons?

Transport dietary triglycerides to adipose tissue.

What is the function of VLDL?

transports hepatic lipids to tissues

What is the function of LDL?

carries cholesterol to cells

What is the function of HDL?

Scavenges cholesterol esters and returns them to the liver for disposal.

What must happen for LDL to deliver cholesterol to a cell, and what happens if receptors are absent?

LDL must bind to LDL receptors on the cell surface to be internalized; without receptors, LDL remains in the bloodstream.

What are monosaccharides and give two examples mentioned?

The simplest carbohydrates; examples include glucose and fructose.

What are disaccharides and give two examples mentioned?

Two monosaccharides linked together; examples include sucrose and lactose (maltose is another example).

What is a glycosidic bond, and why is it important in carbohydrates?

A bond linking monosaccharides in disaccharides; its cleavage requires specific enzymes (e.g., sucrase for sucrose, lactase for lactose).

What are oligosaccharides and polysaccharides, and how are they different?

Oligosaccharides: 3–10 sugars; polysaccharides: more than 10 sugars, often branched (e.g., starch, glycogen, cellulose).