Biochemistry for General Biology

Overview

• Focus on four groups of biological molecules:
  • Lipids: Fats, not soluble in water.
  • Carbohydrates: Starches and sugars.
  • Nucleic Acids: Primarily DNA.
  • Proteins: Components running body reactions and building body structure.
• Connection between DNA and protein synthesis.

Elements in Biochemistry

• Four main elements: Nitrogen, Hydrogen, Carbon, Oxygen.
• Life requires about 25% of elements from the periodic table.
• Elements differ among organisms, e.g., Selenium in humans, not in plants.

Organic Chemistry

• Carbon's atomic number is 6, bonds with four other elements.
• Organic chemistry studies carbon-based compounds.
• Carbon's versatility allows formation of complex molecules (e.g., graphite and diamonds).

Molecular Representation

• Structural representation of molecules varies by context.
• Functional Groups: Areas where reactions occur on molecules.
  • Common functional groups include hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate.

Biological Molecule Groups

Lipids

• Made of carbon and hydrogen, hydrophobic.
• Not polymers, called oligomers.
• Types of Lipids:
  • Fatty Acids: Long carbon chains, saturated or unsaturated.
  • Triglycerides: Glycerol + three fatty acids.
  • Phospholipids: Two fatty acids + phosphate group; critical for cell membranes.

Carbohydrates

• Composed of carbon, hydrogen, oxygen (CHO).
• Monosaccharide: Glucose.
• Polymers:
  • Starch: Plant storage, digestible by humans.
  • Cellulose: Structural, indigestible by humans.
  • Glycogen: Animal storage.

Nucleic Acids

• Polymers: DNA and RNA, built from nucleotides.
• DNA vs RNA:
  • DNA: Deoxyribose sugar, bases A, T, G, C.
  • RNA: Ribose sugar, bases A, U, G, C.
• Nucleotides consist of a phosphate, sugar, and nitrogenous base.
• DNA's double helix structure is key for genetic information storage and transfer.

Proteins

• Made of amino acids (20 types), each with an amino group, carboxyl group, and variable group.
• Assembled by dehydration synthesis.
• Structure:
  • Primary: Linear amino acid sequence.
  • Secondary: Alpha helices and beta sheets.
  • Tertiary: Three-dimensional folding, critical for function.
  • Quaternary: Multiple polypeptide chains forming a functional protein.
• Shape determines function.
• Denaturation: Loss of structure and function due to environmental factors.

Functional Importance

• Proteins perform nearly all functions in the body.
• Nucleic acids store instructions for protein synthesis.

Historical Context

• DNA structure discovered by Watson and Crick in the 1950s, foundational for molecular biology.
• Rosalind Franklin's contribution through x-ray crystallography was crucial, though initially under-credited.