Understanding Lipids: Types and Functions

Favism and G6PD Deficiency

• Favism is linked to G6PD deficiency, causing jaundice from bilirubin absence.
• G6PD deficiency can arise from complications of chronic diseases.

Lipids

• Lipids: enhance flavor, serve as energy sources, and act as thermal insulators.
• Store fat-soluble vitamins A, D, and E; form the backbone of hormones and cell membranes.
• Types of lipids:
  • Simple Lipids: include fats (solid), oils (liquid), and waxes.
  • Compound Lipids: contain myonaises, e.g., lecithin.
  • Derived Lipids: consist of fatty acids, glycerol, steroids, alcohol, and aldehydes.

Cholesterol and Heart Disease

• Cholesterol is essential but excessive levels in blood contribute to heart disease.
• Primarily synthesized in the liver, with some being obtained from dietary sources.

Essential Fatty Acids

• Must be consumed as the body cannot synthesize them.
• Prostaglandins: present in nerves and contribute to pain.
• Thromboxanes: aid in nerve formation.
• Leukotrienes: promote muscle tension and inflammation.
• Prostacyclin: plays a role in blood coagulation balance.
• LDL (low-density lipoprotein): transports cholesterol from liver to tissues.
• HDL (high-density lipoprotein): returns cholesterol from tissues back to the liver.

Enzymes

• Enzymes are biological catalysts, mainly proteins that speed up biochemical reactions.
• Key roles include digestion and toxin elimination.
• Two main sites:
  • Catalytic site: involved in catalysis.
  • Substrate binding site: where reactants bind.
• Properties:
  • Produced by living cells.
  • Serve as powerful catalysts.
  • Highly specific, except for ribozymes.

Importance of Enzymes in Healthcare

• Enzymes provide insights into diseases for diagnosis and prognosis.
• High enzyme levels in serum can indicate tissue damage.
• Can be used therapeutically.

Enzyme Classifications

• Co-factors: non-protein components of holoenzymes.
• Metal-activated enzymes: have loosely bound metals.
• Co-enzymes: low molecular weight, non-protein organic molecules.
• Metalloenzymes: tightly bound metals as prosthetic groups.
• Isoenzymes: different structures with similar functions.

Types of Enzymes

• Oxidoreductase: catalyze redox reactions.
• Transferases: transfer molecular groups.
• Hydrolases: introduce water to cleave bonds.
• Lyases: form double bonds or add groups.
• Ligases: join molecules together.

Factors Affecting Enzyme Activity

• Denaturation caused by pH and temperature changes.
• Vitamins play vital roles in enzyme functions; many cannot be synthesized by mammalian cells.

Vitamins Overview

• Fat-soluble vitamins: A, D, E, K, stored in liver and fatty tissues.
• Water-soluble vitamins: C and B-complex vitamins.

Specific Vitamins and Their Significance

• Vitamin A: necessary for vision; deficiency leads to night blindness and xerophthalmia.
• Vitamin D: regulated calcium metabolism; deficiency causes rickets and osteomalacia.
• Vitamin E: acts as an antioxidant; deficiency leads to increased RBC fragility and neurological disorders.
• Vitamin K: essential for blood clotting; deficiency can lead to hemorrhagic syndrome.
• Vitamin B9 (Folate): found in leafy vegetables; deficiency can result in megaloblastic and macrocytic anemia.

Thalassemia Indicators

• Elevated HbF suggests thalassemia; elevated HbA2 indicates possible heterogeneity.
• Normal ranges for hemoglobin variants:
  • HbA1: 95-98%
  • HbA2: 1.5-3.5%
  • HbF: usually less than 2.5%.