Molecular Biology: RNA and DNA Basics

Ribonucleic Acid (RNA)

• RNA is a single-stranded nucleic acid composed of nucleotides.
• It plays crucial roles in protein synthesis and gene regulation.
• Three main types of RNA exist:
  • Messenger RNA (mRNA): Carries genetic information from DNA to ribosomes.
  • Transfer RNA (tRNA): Brings amino acids to the ribosome during protein synthesis.
  • Ribosomal RNA (rRNA): Forms part of the ribosome structure where proteins are assembled.
• RNA differs from DNA structurally by having a ribose sugar instead of deoxyribose and uracil instead of thymine.

Deoxyribonucleic Acid (DNA)

• DNA is a double-stranded nucleic acid that stores genetic information
• It's a crucial component of all known organisms.
• DNA's structure is a double helix formed by two strands of nucleotides.

Lipid Composition in Plasma Membranes

• Cell membranes are primarily composed of phospholipids.
• Phospholipids consist of a hydrophilic phosphate head and hydrophobic fatty acid tails.
• The arrangement of these molecules in a bilayer forms the basic structure of the plasma membrane.
• Other lipid components include cholesterol, glycolipids, and sphingolipids that contribute to membrane fluidity and function.

Membrane Proteins and Classification

• Membrane proteins are integral to diverse membrane functions.
• Integral proteins are embedded within the lipid bilayer.
  • Transmembrane proteins span the entire membrane.
  • Others are partially embedded.
• Peripheral proteins are loosely associated with the membrane surface.
• Proteins are classified based on their function and structure.
  • Transport proteins regulate the movement of substances across the membrane.
  • Receptor proteins bind to signaling molecules.
  • Enzyme proteins catalyze biochemical reactions.
  • Structural proteins provide support and shape to the membrane.

Carbohydrates and Classification

• Carbohydrates are essential biomolecules with diverse roles in living organisms.
• Major classes of carbohydrates include:
  • Monosaccharides: Simple sugars like glucose, fructose, and galactose.
  • Disaccharides: Two monosaccharides joined together, e.g., sucrose, lactose, and maltose.
  • Oligosaccharides: Short chains of monosaccharides.
  • Polysaccharides: Long chains of monosaccharides.
  • Examples of polysaccharides: starch, glycogen, and cellulose.
    • Starch serves as a storage form of energy in plants.
    • Glycogen is a storage form of energy in animals.
    • Cellulose is a structural component of plant cell walls.
• Carbohydrates in the plasma membrane are often attached to proteins (glycoproteins) or lipids (glycolipids) forming glycocalyx.

This quiz covers the fundamentals of nucleic acids, focusing on the structures and functions of RNA and DNA. You will also learn about the lipid composition in plasma membranes and its significance. Test your knowledge on the roles of different types of RNA in protein synthesis and genetic regulation.