Lipids and Lipoproteins Flashcards
List three disorders of lipid metabolism.
Coronary heart disease, acute pancreatitis, and cataracts
Nearly all of the energy needed by the body is provided by the ____________ of carbohydrates and lipids.
Oxidation
______________ is sourced from dietary fat, and synthesised in the liver cells.
Cholesterol
True or false: cholesterol is readily catabolised.
False
______________ cholesterol can be solubilised, and mixed micelles absorb in the intestine.
Unesterified
In intestinal mucosa, cholesterol is packaged with triglycerides, phospholipids, and specific apolipoproteins. The large, resulting lipoprotein is termed a ‘______________’.
Chylomicron
Cholesterol is important for cell membranes, steroid hormones, and ______ _______.
Bile acids
Where is cholesterol converted to bile acids?
Liver
List two places where cholesterol is required.
Adrenal glands and ovaries
Fatty acids are transported around the body by _______________.
Albumin
Fatty acids are simple chains of C-H bonds, terminating with a ___________ (COOH) group.
Carboxyl
Small amounts of the free form (unesterified) fatty acids are found in the __________, bound to albumin.
Plasma
Most fatty acids are found in ______________ or phospholipids.
Triglycerides
__________ fatty acids have no double bonds.
Saturated
Monounsaturated means ______ double bond.
One
_________________ means two or more double bonds.
Polyunsaturated
Unsaturated fatty acids are usually ______.
Fluid
_______ fatty acids are more similar to saturated fatty acids.
Trans
Triglycerides are also known as _______________.
Triacylglycerols
_________ fatty acid molecules are attached to one molecule of glycerol.
Three
True or false: plasma levels of triglycerides rise after a meal.
True
_________________ consist of two fatty acids.
Phospholipids
In phospholipids, the third position on the _________ ___________ contains the head.
Glycerol backbone
Phospholipids are described as being ‘amphipathic’. What does this mean?
They have both hydrophobic and hydrophilic regions
What is the principal storage unit of lipids?
Adipose tissue
Adipose tissue cells consist of fat ___________ of triglycerides.
Globules
Albumin carries free fatty acids, but how are other lipids transported?
In lipoprotein complexes
Describe the structure of lipoproteins.
Complex spherical structure, with hydrophobic core, wrapped in a hydrophilic coat. The core contains triglyceride and cholesteryl esters. Structures are classified according to density (as isolated by ultracentrifugation, inversely reflecting the size)
______________ are the largest lipoprotein, and they carry dietary triglycerides to the liver.
Chylomicrons
Very low-density lipoproteins (VLDL) carry triglycerides assembled in the _________ to cells for energy needs, or store them as fat.
Liver
Intermediate-density lipoprotein (IDL) is found in __________ amounts, except in pathological disturbances.
Small
_____ ___________ ___________ is almost empty of triglycerides, but rich in cholesterol. It delivers cholesterol to peripheral cells, and subtypes exist.
Low density lipoprotein
High density lipoprotein gathers up extra _____________ for transport, taking it back to the liver (reverse cholesterol transportation).
Cholesterol
_______________ are major component on surface of lipoproteins.
Apolipoproteins
What naming convention do apolipoproteins follow?
Lettering from A to E
List three functions of apolipoproteins.
Maintaining structural integrity
Regulating certain enzymes
Receptor recognition
In _____________ metabolism, lipids are absorbed into the small intestine, then incorporated into a chylomicron.
Exogenous
Describe endogenous metabolism of lipoproteins.
Chylomicron remnant is left, as triglycerides are lost. Liver synthesis of VLDL occurs. VLDL can be converted to IDL by lipoprotein lipase. IDL becomes LDL after further delopidation. HDL can be taken up either directly by the liver, or indirectly, for transfer to other lipoproteins, then return to the liver
_____________ are synthesised by GIT after a meal.
Chylomicrons
Chylomicrons are degraded by lipoprotein ____________ in the capillaries.
Lipases
______ interacts with HDL to form mature VLDL, with added cholesterol and lipoproteins.
VLDL
True or false: LDL is the principal carrier of cholesterol.
True
LDL is removed from circulation by the high-affinity LDL ________.
Receptor
_________ LDL levels promote atherosclerosis.
Elevated
Small, dense, particles are considered the most _______________.
Proatherogenic
What are lipoproteins (a)?
Another family of lipoproteins that consist of LDL and a protein called apo (a); association with coronary heart disease has been observed
LDL receptors are _______________ present on the surfaces of all cells.
Glycoproteins
LDL receptors are concentrated in special membrane recesses called _______ _____.
Coated pits
LDL receptors bind ___ and E apoproteins on the surfaces of lipoproteins.
B
Familial hypercholesterolaemia (FH) is an inherited malfunction, or absence, of ____________.
Receptors
A mutation of apolipoprotein B results in defective binding of LDL, called ________ __________ _____ ___.
Familial defective Apo B
HDL are the ___________ lipoproteins.
Smallest
True or false: HDL contains cholesterol and phospholipids.
True
HDL take cholesterol from extra-hepatic tissues, to the liver for _____________.
Excretion
______ is anti-atherogenic.
HDL
List two functions of HDL.
Transfer of proteins to other lipoproteins, and conversion of cholesterol to cholesteryl esters
Lipid and lipoprotein results are significant for assessing __________ __________ _________ risk status.
Coronary heart disease
What is the reference range for cholesterol?
3.0-5.0 mmol/L
Cholesteryl ester ______________ cleaves fatty acid residue from cholesteryl esters.
Hydrolase
Outline the enzymatic method of cholesterol quantification.
Cholesteryl ester hydrolase cleaves fatty acid residue from cholesteryl esters (which comprise about two-thirds). Enzyme catalyses the conversion of cholesteryl esters to free cholesterol. A second enzyme, cholesterol oxidase, catalyses the reaction of oxygen with cholesterol to produce hydrogen peroxidase. Hydrogen peroxidase is a common substrate for horseradish peroxidase. Peroxidase and dye combine to give a coloured complex
What is the reference range for triglycerides?
0.4-2.0 mmol/L
Triglycerides are required for the ____________ equation, which is used to calculate LDL cholesterol.
Friedewald
Outline the principle of the enzymatic method of quantifying tryglycerides.
Glycerol and ATP with glycerol kinase react to generate glycerophosphate and ADP. Glycerophosphate and oxygen, in the presence of glycerophosphate oxidase react to generate dihydroxyacetone and hydrogen peroxidase. Peroxidase and dye combination follows
True or false: endogenous free glycerol can interfere with methods used.
True
HDL can be measured in _____________, following precipitation.
Supernatant
_________ measurement, which uses modification of cholesterol esterase and oxidase, renders HDL-cholesterol more reactive that in other lipoproteins, and HDL-C is measured selectively.
Direct
LDL cholesterol measurement methods assume that _________ ____________ is made up of VLDL-chol, LDL-chol, and HDL-chol.
Total cholesterol
State the Friedewald equation.
(total cholesterol - HDL cholesterol - (triglyceride/2.2))
LDL may be precipitated selectively with ____________ ___________/heparin (in low pH).
Polyvinyl sulphate
List three methods that can be used to detect lipoproteins.
Ultracentrifugation, electrophoresis, and immunoassays
________________ is caused by hardening of arteries due to deposition of atheromas.
Atherosclerosis
List two conditions with which coronary heart disease is associated.
Angina and myocardial infarction
Cardiovascular disease is especially associated with ________.
Stroke
High levels of cholesterol may be caused by an unhealthy lifestyle, or by __________ ____________.
Genetic abnormalities
________________ is most closely linked abnormality to heart disease.
Hypercholesterolaemia
Hypertriglyceridaemia tends to be caused by genetic abnormalities, such as _________ ___________________.
Familial hypertriglyceridaemia
Hypertriglyceridaemia can lead to _____________ (impaired catabolism of triglyceride-rich protein).
Nephrosis
_______________ hyperlipidaemia involves elevated cholesterol and triglycerides.
Combined
