Advanced Organic and Biochemistry II: Lipids and Hormones Quiz

Phosphatidic acid is known for having an unsaturated fatty acid on C-2, which distinguishes it from other molecules. This structural feature has implications for its function in cell signaling and membrane structure.

Cholesterol transport from the liver involves the transformation of VLDL to LDL, which is then carried in the plasma to specific cells where the cholesterol is utilized. The incorrect answers provide inaccurate information about the process of cholesterol transport.

The COX-1 enzyme is responsible for catalyzing the normal physiological production of prostaglandins in the body.

Leukotrienes are lipid mediators derived from arachidonic acid and mainly found in leukocytes. They are known to produce muscle contractions in the lungs and can trigger asthma-like attacks. Leukotrienes are 100 times more potent than histamine, and some anti-asthma drugs work by inhibiting their synthesis.

Oxidoreductase enzymes are primarily involved in catalyzing oxidation/reduction reactions, where electrons are transferred from one molecule to another. This process is essential for various metabolic pathways and energy production.

Transferases specifically catalyze the transfer of a functional group from one molecule to another. They do not catalyze redox reactions, regulate gene expression, or form peptide bonds.

Hydrolases catalyze hydrolysis reactions by breaking down chemical bonds with the addition of water. The other options do not correspond to the typical function of a hydrolase.

Lysase enzymes primarily catalyze the addition of groups to double bonds or the removal of groups to create double bonds, playing a crucial role in various metabolic pathways.

Isomerases are enzymes that catalyze the structural rearrangement of isomers, facilitating conversions between different isomeric forms of molecules.

Coenzymes are organic molecules that are necessary for enzyme function and catalysis. They often help enzymes to transfer chemical groups between molecules and are essential for various metabolic pathways.

Primary protein structure is the very first level of protein structure and is defined by the specific sequence of amino acids in a peptide chain. It sets the foundation for higher levels of protein structure such as secondary, tertiary, and quaternary structures.

The secondary protein structure refers to the repetitive conformation of the protein backbone, specifically the alpha-helix and beta-pleated sheet arrangements. This is distinct from the primary structure, which is the sequence of amino acids, and tertiary and quaternary structures, which involve higher-order folding and interactions between protein subunits.

Tertiary structure refers to the complete 3D arrangement of atoms in a protein and is stabilized by various interactions like covalent bonds, hydrogen bonds, salt bridges, hydrophobic interactions, and metal-ion coordination. It is distinct from secondary structure, primary structure, and other protein characteristics.

Quaternary protein structure refers to the arrangement of multiple polypeptide chains into a complex, functional protein unit held together by noncovalent interactions.

Feedback control in enzyme regulation involves the product inhibiting an earlier reaction, not activating enzymes by products, inhibiting by initial substrate concentration, or terminating by cofactors.

Glycerophospholipids are a type of lipid that is commonly found in the membranes of plant and animal cells, where they serve important structural roles and are involved in cellular signaling processes.

Glycolipids are complex lipids that consist of a carbohydrate attached to a sphingosine backbone, making them distinct from simple lipids or other biomolecules.

Sphingolipids are a type of lipid found in cell membranes, particularly in the myelin sheath that surrounds nerve cells. They consist of a sphingosine backbone with attached phosphate (PO4) and choline groups.

Sphingosine is a long-chain amino alcohol with 18 carbon atoms and a double bond between C4 and C5.

Cholesterol plays important roles in the body such as being the most abundant steroid, a component of plasma membrane, precursor of hormones & bile salts, and affecting melting point. It does not contribute to muscle growth, is not the primary source of energy, and is not responsible for blood clotting.

Androgens are male sex hormones that are primarily produced in the testes. They are responsible for the development of male reproductive tissues and secondary sexual characteristics.

The correct answer describes the specific function of the COX-2 enzyme in the context of inflammation. The incorrect answers provided are not accurate representations of the role of the COX-2 enzyme.

Thromboxanes are derived from arachidonic acid and play a critical role in inducing platelet aggregation and vasoconstriction. Aspirin and other NSAIDs inhibit the synthesis of thromboxanes by blocking the COX enzyme, thereby affecting blood clotting and blood vessel constriction.

Ligase is an enzyme that is responsible for joining two molecules together, typically through the formation of a covalent bond. This process is essential for various biological functions such as DNA replication, repair, and recombination.

An apoenzyme refers to the protein portion of an enzyme, which requires a cofactor to become fully functional.

Cofactors are nonprotein components of enzymes that assist in catalyzing chemical reactions, they are essential for enzyme function.

A proenzyme/zymogen is an inactive form of an enzyme that requires cleavage of part of its polypeptide chain to become active. It serves as a precursor to the active enzyme.

Glucocorticoid hormones are primarily synthesized in the adrenal cortex and play a crucial role in regulating metabolism, decreasing inflammation, and managing stress responses. They are different from aldosterone, which is a mineralocorticoid hormone.