biochemistry chapter 5: lipid structure and function

What structure do phospholipids form?

Bilayer of biological membranes.

What characterizes the head group of phospholipids?

It is hydrophilic (polar) and attached by a phosphodiester linkage.

How does the saturation of fatty acid tails affect the membrane?

Saturated fatty acids are less fluid than unsaturated ones.

What are glycerophospholipids composed of?

Glycerol backbone and fatty acid tails.

What do sphingolipids contain?

Sphingosine or sphingoid backbone.

What are sphingophospholipids?

Sphingolipids containing a phosphodiester bond.

What class are sphingomyelins a part of?

They are a major class of sphingophospholipids.

What do glycosphingolipids contain?

Attached sugar moieties instead of phosphate groups.

What are cerebrosides?

Glycosphingolipids with one sugar connected to sphingosine.

What are globosides?

Glycosphingolipids with two or more sugars.

What do gangliosides contain?

Oligosaccharides with at least one terminal N-acetylneuraminic acid (NANA).

What are waxes made of?

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

What are the main functions of waxes?

Protection against evaporation and parasites in plants and animals.

What are terpenes made from?

Isoprene, a five-carbon molecule.

What does one monoterpene unit consist of?

Two isoprene units.

What are terpenoids?

Derived from terpenes via oxygenation or backbone rearrangement.

What do steroids consist of?

Three cyclohexane rings and one cyclopentane ring.

What influences steroid hormones?

They have high-affinity receptors and regulate gene expression.

What is the role of cholesterol?

Important for membrane fluidity and stability; precursor to other molecules.

What are prostaglandins?

Signaling molecules that regulate cAMP levels.

What effects do prostaglandins have?

They affect smooth muscle contraction, body temperature, and pain.

List the fat-soluble vitamins.

Vitamins A, D, E, and K

metabolized to retinal for vision and retinoic acid for gene expression in epithelial development

vitamin A (carotene)

metabolized to calcitriol in the kidneys and regulates calcium and phosphorous homeostasis in the intestines, promoting bone formation

vitamin D (cholecalciferol)

A deficiency of Vitamin D causes what condition?

Rickets

acts as biological antioxidant

vitamin E (tocopherols)

important for formation of prothombrin, a clotting factor, and performs posttranslational modifications on a number of proteins, creating calcium-binding sites

Vitamin K

What are triacylglycerols used for?

Preferred method of energy storage

How are triacylglycerols composed?

One glycerol attached to three fatty acids

What characteristic gives lipids more energy than carbohydrates?

Carbon atoms in lipids are more reduced

What cells store large deposits of triacylglycerols?

Adipocytes

What are free fatty acids?

Unesterified fatty acids traveling in the bloodstream

What is saponification?

Ester hydrolysis of triacylglycerols using a strong base

How do soaps function?

Act as surfactants, forming micelles

What can dissolve in the core of a micelle?

Lipid-soluble molecules