Biology Chapter on Nucleic Acids

Properties of Water and Soil Formation

• Water expands when frozen, aiding in rock fragmentation.
• Contributes significantly to soil creation.
• Absence of soil leads to barren land, unfit for plant life.
• Lack of plants results in hostile environments for animals and other organisms.

Carbohydrates: Overview

• Organic compounds consisting of carbon, hydrogen, and oxygen in a 1:2:1 ratio.
• General formula: (CH2O)n.
• Types of carbohydrates: small and soluble (monosaccharides) or long chains (polysaccharides such as starch and cellulose).

Functions of Carbohydrates

• Primary energy source.
• Energy storage and food reserve.
• Structural role in cells (e.g., cell walls).
• Essential component of nucleic acids.
• Provides defense and protection mechanisms.

Monosaccharides

• Simple sugars characterized by simple structures.
• Classified by carbon count:
  • Triose (C3H6O3)
  • Pentose (C5H10O5)
  • Hexose (C6H12O6)
• Common hexose sugars include:
  • Glucose (blood sugar)
  • Galactose (milk sugar)
  • Fructose (fruit sugar)
• Characteristics: sweet, water-soluble, reducing sugars, crystallizable, low molecular mass.

Disaccharides

• Formed from two linked monosaccharides through condensation.
• General formula: C12H22O11.
• Characteristics: sweet, water-soluble, crystallizable, mostly non-reducing sugars, can be hydrolyzed into monosaccharides.
• Common disaccharides:
  • Maltose: Glucose + Glucose; reducing sugar, hydrolyzed by maltase.
  • Sucrose: Glucose + Fructose; non-reducing sugar, hydrolyzed by sucrase.
  • Lactose: Glucose + Galactose; reducing sugar, hydrolyzed by lactase.

Polysaccharides

• Long chains of monosaccharides bonded via glycosidic bonds; formula: (C6H10O5)n.
• Serve as energy storage (e.g., starch) and structural components (e.g., cellulose).

Lipids Characteristics

• Composed mainly of fatty acids and glycerol, non-polar (hydrophobic), and soluble in organic solvents.
• Do not dissolve in water and are resistant to oxidation compared to carbohydrates.
• Major types include triglycerides (fats and oils), waxes, phospholipids, and steroids.

Triglycerides

• Formed by three fatty acids and one glycerol through condensation reactions.
• Solid state: fats; liquid state: oils.
• Fatty acids can be saturated or unsaturated.

Phospholipids and Steroids

• Phospholipids consist of a glycerol molecule, two fatty acids, and a phosphate group, vital for biological membranes.
• Steroids have a structure based on a 17-carbon skeleton, involved in bioactivity (e.g., hormones).

Protein Classification

• Proteins consist of amino acids linked by peptide bonds; classified as:
  • Simple proteins: contain only amino acids.
  • Fibrous proteins: long, insoluble chains; provide structural support.
  • Globular proteins: tightly folded, soluble in water; metabolically active.
  • Conjugated proteins: contain amino acids and non-protein components.

Nucleic Acids

• Formed by linking nucleotides, which consist of a phosphate group, sugar, and nitrogenous base.
• DNA:
  • Sugar: deoxyribose.
  • Contains adenine, thymine, cytosine, guanine.
  • Double-stranded, helix structure, carries genetic information, primarily in the nucleus.
• RNA:
  • Sugar: ribose.
  • Contains adenine, uracil, cytosine, guanine.
  • Single-stranded, crucial for protein synthesis, located in nucleus and cytoplasm.

Nitrogenous Bases

• Two categories:
  • Purines: Adenine, Guanine.
  • Pyrimidines: Cytosine, Thymine (in DNA), Uracil (in RNA).

Test your knowledge on nucleic acids with this quiz. Explore topics like nitrogenous bases, RNA structure, and the location and function of DNA within cells. Perfect for biology students looking to enhance their understanding of these essential biomolecules.