BIO Lecture 1

Lecture Overview

• The lecture focuses on the fundamental aspects of cells, genetics, and phylogenetics through a biological lens.

Cells: The Factories of Life

• Concept of Cells:

  • Cells are likened to factories, which require energy, demand, basic building blocks, and the ability to manage waste, akin to how a factory operates.

  • The smallest unit of life is recognized as the cell.

• Cytoplasm:

  • Cytoplasm is the fluid within the cell, containing various components such as cytosol, organelles, proteins, and ions.

• LUCA (Last Universal Common Ancestor):

  • LUCA represents the most recent common ancestor of all current life forms.

• Semipermeable Membrane:

  • Cells possess a semipermeable membrane that enables selective passage of molecules or ions through osmosis, allowing for precise transport mechanisms within the cell.

Molecular Motors and Life's Diversity

• Motor Proteins:

  • Motor proteins are classified as molecular motors that can traverse the cytoskeleton, contributing to cell movement and function.

• Genomic Diversity:

  • There is significant diversity in genomic structures among model organisms, sparking discussions about the appropriateness of humans as a model species in biological research, reflecting on biases in categorizing domains of life.

• Organotrophs vs. Phototrophs:

  • Organotrophs depend on consuming other organisms, demonstrating that lifestyle choices (e.g., veganism) do not alter this classification.

  • Phototrophs harness energy from sunlight, while lithotrophs derive energy from inorganic compounds.

The Central Dogma of Molecular Biology

• DNA, RNA, and Protein Synthesis:

  • The central dogma encompasses DNA replication, RNA transcription, and protein translation as fundamental processes in biology.

• Nucleotides:

• Nucleotides function as the essential building blocks for DNA and RNA, with specific sequences forming polynucleotides or DNA molecules.

• The process follows: DNA -> RNA (through transcription) -> Protein (through translation with tRNA).

• Regulatory Role of Proteins:

  • Although not explicitly stated in the central dogma, proteins also play roles in regulating the synthesis and breakdown of other proteins and RNA.

Phylogenetics and Genomic Structure

• Phylogenetics Overview:

  • The study of evolutionary relationships via genome size observations, noting specific ranges for Bacteria (580,000 to 1.8 million base pairs), Archaea (470,000 to 1.6 million), and Eukaryotes, such as budding yeasts (12,069,000 base pairs) and humans (3.2 billion base pairs and approximately 20,000 genes).

• Gene Relationships:

  • Important concepts include:

    • Orthologs: Genes associated through evolutionary speciation, sharing a common ancestor.

    • Homologs: Features with shared ancestry, including genes.

    • Paralogs: Genes resulting from duplication events, also possessing a common ancestor.

• Metaphors for DNA Structure:

  • DNA is likened to an alphabet, while a gene is portrayed as a chapter in an organism's 'book', collectively forming the genome.