Lipid Biosynthesis and Fatty Acid Synthesis

Vocabulary practice flashcards covering the principles, cellular compartmentalization, transport mechanisms, and enzymatic machinery of fatty acid synthesis.

Cytosol

The cellular compartment where fatty acid synthesis occurs and where most $NADPH$ production takes place to allow biosynthetic reactions to proceed.

Malonyl CoA

The activated form of acetyl CoA that donates carbons to the growing fatty acid chain during fatty acid synthesis.

Endoplasmic Reticulum (ER)

The organelle where phospholipid synthesis, steroid synthesis, and the majority of fatty acid elongation and desaturation occur.

Peroxisomes

Organelles in plant cells where fatty acid oxidation takes place, producing hydrogen peroxide as $FADH_2$ is oxidized back to $FAD$ using oxygen as the electron acceptor.

Malic Enzyme

An enzyme that converts malate to pyruvate and carbon dioxide while reducing $NADP^+$ to $NADPH$, supplying reducing power for fatty acid synthesis.

Pentose Phosphate Pathway

A metabolic pathway that oxidizes glucose-6-phosphate to release carbon dioxide and generate a significant supply of cytosolic $NADPH$ used in fatty acid synthesis.

Citrate Transporter

A transport protein that carries citrate—formed by combining acetyl CoA and oxaloacetate—out of the mitochondria into the cytosol to deliver acetyl units.

Biotin

The coenzyme used in the conversion of acetyl CoA to malonyl CoA; it becomes activated with carbon dioxide from bicarbonate before transferring the carbon to acetyl CoA.

Commitment Step of Fatty Acid Synthesis

The activation of acetyl CoA by carboxylation to form malonyl CoA, serving as the primary regulatory point of the synthesis pathway.

Acyl Carrier Protein (ACP)

A protein tethered to the fatty acid synthase complex that binds malonyl groups and carries the growing fatty acyl intermediate through rounds of reduction and dehydration.

Phosphopantetheine

The prosthetic group attached to the acyl carrier protein (ACP) that provides a free thiol group derived from pantothenic acid to form thioester bonds with acyl intermediates.

Fatty Acid Synthesis Cycle

A cyclical pathway consisting of condensation, reduction of a ketone to an alcohol by $NADPH$, dehydration to form a carbon-carbon double bond, and a second reduction to a single bond by $NADPH$.

Fatty Acid Synthase I (FAS I)

A single large polypeptide enzyme complex that folds into a defined structure to produce a single, saturated 16-carbon fatty acid product.

Fatty Acid Synthase II (FAS II)

A collection of individual enzymes organized on a scaffold, predominantly found in plants, where enzymes can be swapped out to synthesize fatty acids of variable lengths (12, 14, 16, or 18 carbons) and saturation states.

Lauric Acid

A 12-carbon saturated fatty acid that is the predominant lipid component of coconut oil.

Maleic Acid (in Olive Oil Context)

An 18-carbon monounsaturated fatty acid identified as the predominant fatty acid found in olive oil.