Chapter 5 - Lipids
Gastric lipase is important for the suckling infant for all of the following reasons EXCEPT:
It requires an alkaline environment for optimal activity.
What shape does a carbon-carbon double bond in the trans form?
It will extend the fatty acid into a linear shape.
What lipoprotein is the major carrier of cholesterol to tissues for use in construction of membranes or steroid lipids?
LDL
Which lipoprotein are normally present in blood in the greatest quantity during the fasting state?
LDL
What fatty acids are considered essential and must be supplied by the diet?
Linoleic acid and alpha linoleic acid
What dietary fatty acid family exerts anti-thrombotic properties?
N-3
Carbon-carbon double bonds in the cis form:
Result in a kinking of the fatty acid into a U-shape
Triacylglycerols with saturated fatty acids of longer chain length tend to be ___ at RT?
Solid fats
Ketones are produced from:
acetyl-CoA
Thromboxane A2 is a hormone like substance made from:
arachidonic acid
How many double bonds can a polyunsaturated fat of nutritional interest have?
as many as six double bonds
Prostaglandins exhibit a range of physiological actions including: a. effects on visual development. b. effects on the immune system. c. enhanced fatty acid mobilization. d. enhanced fatty acid synthesis.
b. effects on the immune system.
The physiological effect of thromboxanes derived from omega-3 essential fatty acids are?
platelet inhibitor and vasodilation
What is the function of apolipoproteins?
stimulate enzymatic reactions which regulate the metabolic functions of lipoproteins.
What is the carrier for long-chain dietary fatty acids in circulation?
chylomicrons
Cholesterol is delivered to the liver chiefly in the form of?
chylomicrons remnants
What of the following FA would yield the greatest energy upon complete oxidation? a. oleic acid b. linoleic acid c. alpha-linoleic acid d. stearic acid
d. stearic acid
What antithrombiotic n-3 fatty acid is found in fish oil?
eicosapentaenonic
Undigested lipid delays the rate of emptying of stomach contents, thus:
it delays hunger
What organ provides the major site for lipoprotein formation from endogenously produced lipids?
liver
Carnitine is the carrier molecule needed for:
mitochondrial membrane transport of FA and their CoA derivatives.
Sphingomyelins are important phospholipids found in the ____.
myelin sheath of nerves
The fatty acid synthase system is involved in creating?
palmitate from acetyl CoA.
Why does undigested lipids in the stomach create satiety?
It delays the rate of emptying of stomach contents
What is the structure of a phospholipid?
A phospholipid has a glycerol backbone with two fatty acids with one chain attached by a phosphate.
During beta oxidation of FA through cyclic degradative pathway, how many carbon units in the form of acetyl-CoA are cleaved at a time from the carboxyl end?
2 carbon units
From what product is cholesterol produced from?
Acetyl-CoA
Leukotrienes are hormone-like substances made from what fat?
Arachidonic Acid
During the catabolism of TAC, the glycerol portion of the molecule is used for energy production in which system?
Glycolysis
Why are trans unsaturated fatty acids considered more atherogenic than saturated fatty acids?
Because they elevate serum LDL while decreasing HDL.
What is the best description of the action of bile acids?
Bile emulsifies dietary lipid to increase its surface area.
How does Orlistat reduce absorption of dietary fat?
By inhibiting the activity of pancreatic lipase
Pancreatic Lipase is characterized by which of the following statements? a. It hydrolyzes short-chain FA from the sn-3 position. b. It can readily penetrate milk fat globules without bile salt stabilization. c. It requires an alkaline environment for optimal activity. d. It is highly stable in an acid environment.
C. It requires an alkaline environment for optimal activity.
What compounds does cholesterol serve as a precursor?
Cholesterol serves as a precursor for many other important steroids in the body, like bile acids, sex hormones, corticosteroids and vitamin D3.
Which lipoprotein are not normally present in blood in the fasting state?
Chylomicrons because they form after a meal
What is the most important unsaturated fatty acid serving as a precursor for eicosanoids that antagonize those made from an omega-6fatty acid precursor?
Eicosapentaenoic Acid
LDL binds to which cells in the body with high affinity and specificity?
Fibroblasts cells
Reverse cholesterol transport that removes cholesterol from peripheral cells and return it to the liver is carried out by what lipoprotein?
HDL
What enzyme is inhibited by drug therapy to decrease serum cholesterol?
HMG CoA reductase
What is a major risk factor for CVD?
High levels of circulating LDL
Ketogenesis would be highest in what events? What are the others?
Highest in prolonged starvation and others are low CHO diet, uncontrolled DM and prolonged exercise.
What occurs from a high rate of ethanol ingestion?
Increase in fatty acid synthesis
What are the two major components implicated in the mechanism of atherogenesis?
Inflammation and serum lipids
What hormone inhibits hormone-sensitive triacylglycerol lipase found in adipose tissue cells?
Insulin
What hormone is considered to be antagonist of lipolysis?
Insulin
When CHO are low during fasting, prolonged exercise or uncontrolled diabetes, what compound is converted to glucose?
Oxaloacetate
What is the most common lipid characterized by a cyclized internal segment in a 20 carbon chain?
Prostaglandins
In what form is most body fat stored?
Triacylglycerol