Biochemistry : Lipid Classifications
Study concepts, example questions & explanations for Biochemistry
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Example Questions
Example Question #1 : Sphingolipids
The myelin sheaths of neurons typically contain large quantities of __________.
triacylglycerols
waxes
sphingolipids
cholesterol
sphingolipids
Myelin sheaths surround nerve cell axons and are essential for proper nervous system function. They act as an electrically insulating layer and enable better propagation of action potentials. Sphingomyelin is a type of sphingolipid found in the myelin sheaths of animal cell membranes.
Example Question #1 : Other Lipid Classifications
Which of these lipid molecules has a different fundamental structure than the others?
Glycolipids
Sphingolipids
Cholesterol
Triglyceride
Fatty acids
Cholesterol
Cholesterol is made up of multiple rings, including three six-carbon rings and one five-carbon ring. This characteristic structure is also seen in steroid hormones and metabolites, as many biologically relevant molecules are derived from cholesterol. Fatty acids are long hydrocarbons (typically between ten and thirty carbons long) with carboxylic acid functional groups on one end. Glycolipids are lipids that have carbohydrate moieties attached, which play a role in cellular and molecular communication. Sphingolipids are a class of lipids that contain a sphingoid base backbone and include sphingosine, sphingomyelin, ceramides, gangliosides and others.
Example Question #2 : Other Lipid Classifications
Glycolipids are characterized by which non-lipid component?
Sphingosine
Polypeptide
Phosphate
Sugar
Sugar
The prefix "glyco-" means "sugar." Glycolipids are thus lipids that have a sugar component. Glycolipids containing sphingoid bases are called sphingolipids. Glycolipids containing phosphate are called phospholipids. Lipoproteins are molecules that contain both lipid and peptide components.
Example Question #2 : Other Lipid Classifications
Lipids built from the five-carbon unit isoprene are called __________.
sphingolipids
glycerophospholipids
lipoproteins
terpenoids
sphingomyelins
terpenoids
Terpenoids (also called isoprenoids) are produced mostly by plants. Many vitamins such as A, E, and K are terpenoids, and steroids/sterols also belong to this group.
Example Question #2 : Other Lipid Classifications
There are many different lipoproteins used by the body to transport lipids and cholesterol. Which of the following is a true statement about lipoproteins?
HDL carries lipids that are synthesized in the liver.
VLDL is the largest of the lipoproteins.
LDL is a dense lipoprotein that carries dietary fats around the body.
HDL is a dense lipoprotein that carries cholesterol from the body to the liver.
Chylomicrons are very dense lipoproteins that carry dietary fats.
HDL is a dense lipoprotein that carries cholesterol from the body to the liver.
Only "HDL is a dense lipoprotein that carries cholesterol from the body to the liver" is a true statement. Chylomicrons are the largest and least dense lipoprotein, and they carry dietary lipids. VLDL carries lipids synthesized in the liver to the body. they are more dense the chylomicrons. LDL carries cholesterol around the body, and HDL is the most dense and carries cholesterol to the liver for breakdown.
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