Lipoprotein

Question 1

The chemical structures of the four main forms of lipid present in plasma are

Answer 1

Phospholipid, cholesterol, triglycerides, cholesterol esters

Question 2

Because lipids are relatively insoluble in aqueous media, they are transported in body fluids as, often spherical, soluble protein complexes called lipoproteins.

Question 3

The water-soluble (polar)
groups of proteins, phospholipids and free cholesterol face outwards and surround an inner insoluble (nonpolar) core of triglyceride and cholesterol esters

Question 4

Lipoproteins are classifi ed by their buoyant density, which inversely refl ects their size. The greater the lipid to protein ratio, the larger their size and the lower the density.

Question 5

Lipoproteins can be classified into _____ main groups which are?

Answer 5

five

Chylomicrons
● Very low-density
● Intermediate-density lipoproteins (IDLs),
Low-density lipoproteins
● High-density lipoproteins (HDLs)

Question 6

Which lipoprotein are not
normally present in plasma?

Answer 6

IDL

Question 7

Define & classify the lipoproteins

Answer 7

● Chylomicrons are the largest and least dense
lipoproteins and transport exogenous lipid from the
intestine to all cells.
● Very low-density lipoproteins (VLDLs) transport
endogenous lipid from the liver to cells.
● Intermediate-density lipoproteins (IDLs), which
are transient and formed during the conversion of
VLDL to low-density lipoprotein (LDL), are not
normally present in plasma.
The other two lipoprotein classes contain mainly
cholesterol and are smaller in size:
● Low-density lipoproteins are formed from VLDLs
and carry cholesterol to cells.
● High-density lipoproteins (HDLs) are the most dense lipoproteins and are involved in the transport of cholesterol from cells back to the liver (reverse HDL cholesterol transport). These lipoproteins can be further divided by density into HDL2
and HDL3.

Question 8

Fasting plasma from normal individuals contains only?

Answer 8

VLDL, LDL and HDL particles

Question 9

What’s the The Friedewald equation?

This equation makes certain assumptions, namely
that the patient is fasting and the plasma triglyceride
concentration does not exceed 4.5 mmol/L (otherwise
chylomicrons make the equation inaccurate)

Answer 9

LDL cholesterol
= total cholesterol – HDL cholesterol
–
[triglyceride] / 2.2

Question 10

The proteins associated with lipoproteins are called

Answer 10

apolipoproteins (apo)

Question 11

There are different types of apolipoproteins, each associated with specific lipoprotein particles and functions list them

Answer 11

ApoA: Mainly includes apoA1 and apoA2, primarily associated with high-density lipoprotein (HDL) particles. HDL is involved in reverse cholesterol transport, carrying cholesterol from cells back to the liver.

ApoB: The main type is apoB100, which is found predominantly with low-density lipoprotein (LDL) particles. LDL carries cholesterol to cells and apoB100 serves as a ligand for the LDL receptor, facilitating cellular uptake of cholesterol. Each LDL particle contains one molecule of apoB100.

ApoC and ApoE: These apolipoproteins play significant roles in triglyceride metabolism. They can interchange between various lipoproteins and are crucial in lipid transport and metabolism.

Question 12

The five main classes of lipoproteins are:

Answer 12

Chylomicrons:

Largest and least dense.

Transport exogenous lipids from the intestine to all cells.

Scatter light, causing plasma to appear turbid (lipaemic) when in high concentrations.

Very Low-Density Lipoproteins (VLDLs):

Transport endogenous lipids from the liver to cells.

Intermediate in size and density.

Intermediate-Density Lipoproteins (IDLs):

Transient particles formed during the conversion of VLDLs to LDLs.

Not normally present in plasma.

Low-Density Lipoproteins (LDLs):

Formed from VLDLs.

Carry cholesterol to cells.

Lower density, more associated with cholesterol transport to peripheral tissues.

High-Density Lipoproteins (HDLs):

Most dense lipoproteins.

Involved in reverse cholesterol transport, carrying cholesterol from cells back to the liver.

Can be further divided into HDL2 and HDL3 based on density.

Question 13

Apolipoprotein Ratios: The plasma apoA1 to apoB ratio is a potential marker for cardiovascular risk, with a lower ratio (<1) indicating higher risk. This ratio remains unaffected by the fasting status of the patient.

Question 14

What’s Lipoprotein-Associated Phospholipase A2 and it’s clinical application?

(PAFAH)

Answer 14

Lipoprotein-Associated Phospholipase A2 (PAFAH): Mainly found on LDL and to a lesser extent HDL. It is produced by inflammatory cells, involved in atherosclerosis formation, and associated with increased risk of coronary artery disease and stroke.

Question 15

What’s Lipoprotein Behavior in Plasma in Postprandial & fasting plasma

Answer 15

Lipoprotein Behavior in Plasma

Postprandial Lipemia: After a meal, plasma may appear turbid due to the presence of chylomicrons. When such a sample is left overnight at 4°C, chylomicrons form a creamy layer on the surface, whereas VLDL and IDL particles remain suspended and do not rise.

Fasting Plasma: In normal fasting individuals, plasma contains only VLDL, LDL, and HDL particles. These do not cause turbidity as they are smaller and do not scatter light.