Lipids: Structure, Function, and Classification

A set of vocabulary flashcards summarizing key concepts and definitions related to lipids from the lecture notes.

What percentage of water do most cells and organisms contain?

70% to 80%.

What are the four major families of macromolecules?

Proteins, Nucleic acids, Carbohydrates, Lipids.

What are macromolecules?

Large organic molecules.

What does 'organic' means in terms of macromolecules?

Based on carbon chemistry.

What are lipids?

Broad class of molecules that are insoluble in water.

What are triglycerides?

Form of energy storage in adipocytes.

How much energy does fat release when oxidized?

9 kcal per gram.

What are biomembranes primarily made of?

Phosphoglycerides, sphingolipids, and steroids.

What role do bioactive lipids play?

They act as signaling molecules in cells.

What are enzymatic co-factors?

Substances that help enzymes function.

What is the biological function of lipids?

Diverse roles including energy storage and cellular structure.

What are ether lipids?

Specialized lipids with ether-linked fatty alcohols.

What are plasmalogens?

A subgroup of ether lipids with a vinyl ether bond.

What is the difference between hydrophobic and amphipathic lipids?

Hydrophobic lipids are water-hating; amphipathic have both water-soluble and insoluble regions.

What are fatty acids?

Carboxylic acids with hydrocarbon chains of 4 to 36 carbons.

What characterizes saturated fatty acids?

Only single bonds between carbon atoms.

How does unsaturation affect fatty acids?

Creates kinks in the chain, preventing tight packing.

What are eicosanoids?

Fatty acid derivatives that serve as signaling molecules.

What are steroid hormones derived from?

Cholesterol.

What are the functions of bile salts?

Emulsifying fats for digestion and absorption of fat-soluble vitamins.

What is palmitate?

A saturated fatty acid and precursor to other fats.

What is the lipophilic property of steroid hormones?

Allows them to diffuse through cell membranes.

What are functions of triglycerides?

Energy storage, buoyancy, and thermal insulation.

What is the structure of a phospholipid?

Glycerol backbone, two fatty acids, and a phosphate group.

How does structural isomerism affect fatty acids?

Results in different arrangements of the same molecular formula.

What is cis vs. trans configuration in fatty acids?

Cis has hydrogens on the same side of the double bond; trans has them on opposite sides.

What is the role of glycerophospholipids?

Form the lipid bilayer of biological membranes.

What is sphingolipid?

A class of lipids built on a sphingoid base.

What role does cholesterol play in cell membranes?

Stabilizes membrane fluidity.

What is a major function of lipid-soluble vitamins?

They are stored in adipose tissue.

What is the significance of the amphipathic nature of membrane lipids?

Allows for the formation of the lipid bilayer.

How do triglycerides compare to carbohydrates in energy yield?

Triglycerides yield more energy per gram than carbohydrates.

What are waxes used for in biological systems?

Energy storage and water repellency.

What do eicosanoids regulate?

Inflammation and pain response.

What is the function of dolichols in the body?

Activate sugar precursors for biosynthesis.

What is a triacylglycerol?

Another name for triglycerides.

What do lipids serve as in photosynthetic membranes?

Structural components essential for photosynthesis.

What ion does calcium bind to in biological pathways?

Calcium ions play key roles in cell signaling and function.

What do phospholipids and sphingolipids have in common?

Both are key components of cellular membranes.

How are dietary fats absorbed?

They are emulsified by bile salts for absorption in the intestines.

What is the importance of unsaturated fatty acids in nutrition?

They are essential for health and must be obtained through diet.

How do lipids function as messengers?

They transmit signals between cells to influence responses.

What physiological processes do steroid hormones regulate?

Growth, metabolism, and the immune response.

What is the basic structure of a sterol?

A four-ring carbon structure.

What health risks are associated with high levels of saturated fats?

Increased risk of cardiovascular diseases.

What molecule is a direct precursor to eicosanoids?

Arachidonic acid.

What role do sphingolipids play in the nervous system?

They are crucial for brain development and signal transduction.

Why are fatty acids considered building blocks of lipids?

They are the primary components forming various lipid structures.

What distinguishes galactolipids from phospholipids?

Galactolipids lack a phosphate group and are primarily found in plants.