36 Questions
Where does the process of lipogenesis primarily occur?
Cytosol
What enzyme adds a phosphate to glycerol in the liver?
Glycerol kinase
What enzyme converts dihydroxyacetone phosphate (DHAP) to glycerol-3-phosphate in adipose and liver?
Glycerol-3-phosphate dehydrogenase
What is the enzyme responsible for adding the first two fatty acid chains to glycerol-3-phosphate in lipogenesis?
Acyltransferase
What is the product of the breakdown of citric acid that serves as a substrate for fatty acid synthesis?
Citrate
Which lipid molecules contain a polar phosphate-alcohol head group?
Phospholipids
What are the first three steps in the synthesis of phosphoglycerides (phospholipids)?
Formation of glycerol-3-P, activation of fatty acids, addition of fatty acids to glycerol-3-P
What is the final step to convert phosphatidic acid to other phospholipids?
Dehydration
What glycolysis intermediate can shunt into lipogenesis?
Pyruvate
What product of the pentose phosphate pathway is used to help make fatty acids?
NADPH
What is the enzyme that is activated by citrate, a product of citric acid breakdown, and is involved in lipogenesis?
Acetyl CoA carboxylase
Where are phosphoglycerides primarily synthesized?
Endoplasmic reticulum
Where does fatty acid synthesis occur?
Cytoplasm
Which enzyme complex is involved in fatty acid synthesis?
Fatty acid synthase
What is the primary substrate for fatty acid synthesis?
Acetyl CoA and malonyl CoA
Which hormones are involved in the regulation of fatty acid synthesis?
Glucagon and insulin
What effect do glucagon and epinephrine have on acetyl CoA carboxylase?
Inhibit it
Which type of fatty acids are needed to be obtained from the diet?
Essential fatty acids
What is the primary location for the elongation of the fatty acid chain?
Endoplasmic Reticulum
Which coenzymes are required for fatty acid synthesis?
B7 (biotin) and B3 (NADPH)
What is the primary method of production for trans fats?
Partial hydrogenation
What effect does insulin have on fatty acid synthesis?
Promotes it
What effect do desaturase enzymes have on fatty acids?
Create double bonds in unsaturated fatty acids
How can odd-numbered fatty acid chains be produced?
Starting with propionyl CoA
What is the precursor for steroid hormones?
Cholesterol
What are sphingolipids like sphingomyelin important components of?
Cell membranes and myelin
What can accumulation of sphingolipids lead to?
Sphingolipid storage diseases
What are waxes mixtures of?
Non-polar molecules, including fatty acids linked to long-chain hydrocarbon alcohols via ester bonds
What serves as a precursor for steroid hormones?
Cholesterol
What are eicosanoids derived from?
Arachidonic acid
What is the rate-limiting step in cholesterol synthesis?
Catalyzed by HMGCoA reductase
What are plant sterols able to do in relation to cholesterol?
Compete with intestinal cholesterol absorption and help lower LDL cholesterol levels
What are cardiac glycosides like digoxin derivatives of?
Plant sterols
What are isoprenoid structures like terpenes made from?
Isoprene units linked together
What are cerebrosides and gangliosides examples of?
Glycosphingolipids
What is the structure of sphingolipids like sphingomyelin?
Phospholipids with a sphingosine backbone
Study Notes
Lipid Structures and Functions Overview
- Phosphoglycerides synthesis involves adding a CMP as a leaving group and attaching the head group via nucleophilic substitution
- Sphingolipids like sphingomyelin are phospholipids with a sphingosine backbone and are important components of cell membranes and myelin
- Cerebrosides and gangliosides are glycosphingolipids, with different head groups and found in neuronal cell membranes
- Accumulation of sphingolipids leads to sphingolipid storage diseases, such as Tay-Sachs Disease, causing progressive neurodegeneration
- Eicosanoids are derived from arachidonic acid and have various physiological functions, including vasodilation and platelet aggregation
- Waxes are mixtures of non-polar molecules, including fatty acids linked to long-chain hydrocarbon alcohols via ester bonds
- Isoprenoid structures include terpenes, mixed terpenes, and steroids, with cholesterol serving as a precursor for steroid hormones
- Terpenes are made from isoprene units linked together and can include examples like CoQ and Vitamin K
- Cholesterol synthesis starts with 3 acetyl CoA molecules, with the rate-limiting step being catalyzed by HMGCoA reductase
- Most cholesterol synthesis occurs in the liver, and cholesterol is a precursor to steroid hormones and is converted to pregnenolone
- Plant sterols have a similar structure to cholesterol, can compete with intestinal cholesterol absorption, and help lower LDL cholesterol levels
- Cardiac glycosides, like digoxin, are derivatives of plant sterols and can affect the heart's function
Test your knowledge of lipid structures and functions with this overview quiz. Explore topics such as phosphoglycerides synthesis, sphingolipids, eicosanoids, waxes, isoprenoids, cholesterol synthesis, and more. Perfect for students and enthusiasts of biochemistry and molecular biology.
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