Biochemistry Fundamentals: Amino Acids, Lipids, and Cytoskeleton
1. Differentiating Basic Amino Acids (2 Examples Each)
Basic amino acids possess R-chains that contribute negatively charged carboxyl groups or positively charged amino groups. Basic amino acids are characterized by having positively charged amino groups in their R-chains.
- Acidic Amino Acids: Glutamic acid, aspartic acid.
- Basic Amino Acids: Lysine, histidine.
2. Distinguishing Molecules: Glycerides vs. Phosphoglycerides
Phosphoglycerides are lipid molecules where one primary hydroxyl group of glycerol (at carbon 1 or 3) is esterified with phosphoric acid. The other two hydroxyls are esterified with fatty acids, typically an unsaturated fatty acid at carbon 2.
Glycerides (simple or neutral fats) are formed by glycerol esterified with one, two, or three fatty acids, resulting in:
- Monoacylglycerides (one fatty acid)
- Diacylglycerides (two fatty acids)
- Triglycerides (three fatty acids)
3. Complex Polysaccharides: Definition and Examples
Complex polysaccharides are formed from many monosaccharide units. They are typically crystalline, insoluble in water, and lack a sweet taste.
- Chitin: A polymer of acetylglucosamine found in the exoskeletons of arthropods.
- Pectins: Polymers of galacturonic acid that form part of the cementing matrix surrounding plant cell walls.
- Heparin: Possesses anticoagulant functions, composed of glucosamine, glucuronic acid, and sulfuric acid radicals in a specific structure.
4. Glyceraldehyde Chemical Structure and Classification
Glyceraldehyde-3-phosphate belongs to the triose family of aldoses and is an isomer of dihydroxyacetone phosphate.
Chemical Structure Scheme
(Note: A visual scheme cannot be rendered in this text-based format, but glyceraldehyde is a three-carbon sugar with an aldehyde group.)
Classification:
- By Chemical Group: Aldose (due to the aldehyde group).
- By Carbon Number: Triose (three carbons).
5. Intermediate Filament Diversity Across Cell Types
Intermediate filaments are not equal in all cell types. They are classified based on the specific protein they contain, which dictates their function and location within the cytoskeleton.
Known Intermediate Filament Types:
- Keratins
- Vimentin
- Desmin
- Glial Fibrillary Acidic Protein (GFAP)
- Neurofilament
- Nuclear lamins (Nuclear sheets)
- Nestin
6. Proteins Associated with Microfilaments and Their Effects
Several proteins interact with microfilaments (actin) to regulate structure and function:
- Troponin, Calmodulin: Affect actin-myosin interactions.
- Profilin, Gelsolin: Regulate the polymerization and depolymerization of actin.
- Fodrin, Filamin: Proteins that intertwine to form actin networks.
- Fimbrin, Fascin, Villin: Intertwine with actin to form parallel bundles.
- Alpha-actinin, Vinculin, Talin: Proteins that anchor actin to the plasma membrane.