Question

1. Discuss the composition and function of the major circulating lipoproteins.

2. List and define 3 major roles of proteins in the body, excluding energy production.

Answer 1

1.There are four major classes of circulating lipoproteins, which have their own characteristic protein and lipid composition.

1. Chylomicrons: It is a small fat globule which is composed of protein and lipid

Composition: Triglycerides (85–92%), phospholipids (6–12%), cholesterol (1–3%), and proteins (1–2%).

Function: It serves in transport of fat from its port of entry in the intestine to the liver and to adipose tissue.

2. Very low-density lipoproteins (VLDL):

Composition: Cholesterol, triglycerides, and proteins.

Function: It  transport internal triglycerides, phospholipids, cholesterol. Functions as the body's internal transport mechanism for lipids.

3. Low-density lipoproteins (LDL)

Composition:cholesterol ( approx 50%)

Protein (25%)

Function: The function is to deliver cholesterol to cells, where it is used in membranes, or it can be used for the synthesis of steroid hormones.

4. High-density lipoproteins (HDL)

Composition: Highest proportion of proteins to lipids.

Function: It carries cholesterol from other parts of the body back to the liver. Liver then removes the cholesterol from the body.

2. Three major roles of proteins in body:

Growth and Maintenance: Body needs protein for growth and maintenance of tissues.

Provides Structure: Some proteins are fibrous and provide stiffness and rigidity to the cells and tissues

Balances Fluids: Proteins regulate body processes to maintain fluid balance.