Medical Biochem Week 2 - Building Blocks of Life

Building blocks of Life

The Chemical Elements of Life

• Six abundant non-metallic elements: ( C, H, N, O, P, S ) (CHNOPS) account for >97% of the weight of most organisms.
• Essential ions and trace elements
  • Five essential ions: Na, K, Mg, Ca, Cl
  • Common trace elements include various metals important in enzymatic functions.

Bonding Between Elements

• Covalent Bonds:

  • Involves sharing of electron pairs between atoms, leading to very stable bonds.
  • All CHNOPS elements can form covalent bonds, including single, double, and triple bonds.
  • Polar Covalent Bonds: Electrons are not shared equally between atoms.

• Hydrogen Bonds:

  • Attraction between positively charged Hydrogen and electronegative atoms (O, N).
  • Crucial for maintaining the structure of DNA and proteins.
  • Water (H2O) is a polar molecule that forms hydrogen bonds, making it vital for all forms of life.

Functional Groups in Biochemistry

• Common functional groups:
  • Carboxyl (-COOH), hydroxyl (-OH), amino (-NH2), phosphate (-PO4) etc.
  • Functional groups determine the properties of biological molecules and their reactivity.

Biochemistry Overview

• Definition: Biochemistry describes the structure, organization, and functions of living matter in molecular terms.
• Main Areas:
  1. Structural Chemistry
  2. Metabolism: Totality of chemical reactions in living matter.
  3. Chemistry of biological information: Storage and transmission of information.
• Multidisciplinarity: Requires knowledge in physics, chemistry, cell biology, molecular biology, medicine, genetics, physiology, evolution, epigenetics.

Macromolecules - Building Blocks of Life

• Types of Macromolecules:
  • Nucleic acids (RNA, DNA)
  • Proteins (Amino Acids)
  • Carbohydrates (Sugars)
  • Lipids (Fats)

Nucleic Acids

• Nucleotides:
  • Composed of a five-carbon sugar, nitrogenous base, and phosphate groups.
  • Forms include DNA and RNA.
  • ATP: Fundamental energy molecule.
• Structure:
  • Polynucleotide chains linked by phosphodiester bonds.
  • DNA is antiparallel and comprises complementary base pairs (A-T, C-G).

Amino Acids and Proteins

• Amino Acids: Building blocks of proteins comprising central carbon, amino group, carboxyl group, and R group.
• Standard Amino Acids: 20 types classified based on the nature of their R groups (neutral, negative, positive).
• Protein Structure:
  • Primary structure: Amino acids linked via peptide bonds during dehydration.

Carbohydrates

• Types:
  • Simple Carbohydrates: Monosaccharides (e.g., glucose) and disaccharides.
  • Complex Carbohydrates: Oligosaccharides and polysaccharides (e.g., glycogen, starch).

Lipids - Triacylglycerols

• Triacylglycerols (TAG): Composed of three fatty acids linked to a glycerol backbone.
• Functions: Major energy storage form within living organisms.

Cells - The Essence of Life

• Cell Types:
  • Eukaryotic: Cells with organelles and nucleus.
  • Prokaryotic: Cells without a membrane-bound nucleus (e.g., bacteria).
• Common Features:
  • Plasma membrane, cytoplasm, ribosomes, genetic material (Nucleus/Nucleoid).

Organelles and Their Functions

• Mitochondria: Site of ATP production.
• Endoplasmic Reticulum: Rough ER synthesizes proteins; Smooth ER synthesizes lipids.
• Golgi Apparatus: Modifies and packages proteins for transport.
• Lysosomes: Involved in degradation and recycling within the cell.

Structural Features of DNA and RNA

• DNA Structure: Double helix composed of nucleotide monomers, forming a sugar-phosphate backbone with complementary base pairing (GC, TA).
• RNA Structure: Generally single-stranded, less stable than DNA, plays essential roles in protein synthesis.

Stability of Nucleic Acids

• Stability: DNA is generally more stable due to covalent phosphodiester backbones, while RNA is more reactive and less stable under alkaline conditions.

Nucleosomes

• Packaging of DNA: DNA wraps around histones to form nucleosomes, essential for gene regulation and organization within the nucleus.