Key Concepts in Lipid Biology and Metabolism

Flashcards covering key terms and definitions related to lipid biology and metabolism, including lipid types, functions, metabolic pathways, and enzymatic regulation.

Lipids

Molecules of biological origin that are freely soluble in organic solvents and almost insoluble in water.

Fatty Acids

Carboxylic acids with long chain hydrocarbons (tails), usually containing 14-30 carbons.

Saturated Fatty Acids

Fatty acids without double bonds in their carbon chains, such as stearic acid.

Unsaturated Fatty Acids

Fatty acids that contain double bonds; can be monounsaturated (one double bond) or polyunsaturated (more than one double bond), e.g., oleic and linoleic acids.

Glycerophospholipids

Lipids that contain glycerol, phosphate, and two fatty acids; crucial components of cell membranes.

Triacylglycerols

Fatty acid triesters of glycerol, known for energy storage in adipose tissue.

Membrane Fluidity

Determined by the fatty acid composition; more fluid membranes require shorter, unsaturated fatty acids.

Micelles

Structures formed by amphipathic molecules in solution, with a larger, polar head than tail.

Liposomes

Spherical vesicles formed from lipids arranged in bilayers that can enclose dissolved molecules.

Biological Functions of Lipids

Includes energy storage, insulation, water repellency, membrane structure, signaling, and protection.

Glycolysis

The metabolic pathway that converts glucose into pyruvate, generating NADH and ATP.

Gluconeogenesis

The synthesis of glucose from non-carbohydrate precursors, utilizing ATP and GTP.

Pentose Phosphate Pathway

A metabolic pathway producing NADPH and ribose-5-phosphate for biosynthesis and antioxidant defense.

Fructose 2,6-Bisphosphate

A regulator of glycolysis and gluconeogenesis; not an intermediate of glycolysis.

Active Transport

The movement of solutes across membranes against their concentration gradient, requiring energy.

Hydropathy Plots

Graphs used to predict the transmembrane domains of proteins based on amino acid characteristics.

Acetyl-CoA

A central metabolic intermediate formed from pyruvate that enters the citric acid cycle.

What are the main steps of glycolysis?

The main steps of glycolysis include: 1) Glucose phosphorylation, 2) Isomerization, 3) Phosphorylation (using ATP), 4) Cleavage, 5) Isomerization, 6) Oxidation and phosphorylation, 7) ATP generation (substrate-level phosphorylation), 8) Second ATP generation.

What are the results of glycolysis?

The results of glycolysis are 2 molecules of pyruvate, 2 ATP (net gain), and 2 NADH.

What enzyme is used in glycolysis to convert glucose to glucose-6-phosphate?

The enzyme used is hexokinase.

What enzyme is involved in the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate?

The enzyme is phosphofructokinase-1 (PFK-1).

Which enzyme catalyzes the conversion of phosphoenolpyruvate (PEP) to pyruvate?

The enzyme is pyruvate kinase.