Biology One Notes

Course Introduction

  • Welcome to Biology One: Molecules, Genes, and Cells.
  • Lectures are in person and live-streamed; recordings are available.
  • Pre-lecture videos are essential, with examinable content.
  • This week includes workshops (no preparation needed) and a lab induction (enclosed shoes required).
  • Practical exemptions are available for students with a previous score of 65% or higher.
  • Biology and chemistry background resources are available on MyUni.

Biological Achievements

  • Eradication of Smallpox: A major victory, highlighting the power of vaccines.
    • Smallpox killed 300-500 million in the 20th century alone with a 30% infection fatality rate.
    • Eradicated in 1977 through global vaccination efforts.
  • Near Eradication of Polio: Significant progress made through vaccination.
    • Cases reduced from 350,000 in 1988 to just 12 last year.
  • Sequencing the Human Genome: A milestone achieved in 2001.
    • Cost has dramatically decreased from 100million100 million to under 350350 in recent years.
  • Mapping of Nematode Development: Complete mapping of cell development in C. elegans, which has exactly 959 body cells.
  • Curing Sickle Cell Anemia: Potential cure through CRISPR gene editing.
  • Cultured Meat: Growing meat cells in a vat with the potential to reduce land/water use and improve animal welfare.

Future Biological Challenges

  • Continuing the fight against infectious diseases (e.g., future COVID waves, influenza pandemics).
  • Protecting native species amidst climate change and habitat loss.
  • Growing food efficiently in drier climates.
  • Combating antibiotic resistance.
  • Ethical use of CRISPR gene editing.

How to Contribute

  • Pursue careers in biology, healthcare, science communication, or consultancy.
  • Volunteer for NGOs or participate in citizen science.
  • Donate to effective charities.

History of Life

  • Earth formed approximately 4.6 billion years ago.
  • First fossils of single-celled organisms appeared about 4.1 billion years ago.
  • Multicellular organisms emerged around 600 million years ago.
  • Plants colonized land, followed by reptiles (including dinosaurs).
  • Humans appeared in the last few million years.
  • Photosynthesis evolved in cyanobacteria around 2.7 billion years ago, leading to mass devastation due to oxygen production.

The Three Domains of Life

  • Eukarya (Eukaryotes): Includes all multicellular organisms (animals, plants, fungi) and many single-celled organisms.
  • Bacteria: Exclusively single-celled and microscopic, found everywhere; most are harmless.
  • Archaea: Exclusively single-celled, similar to bacteria in appearance, found in extreme environments; no known pathogens.

Cell Facts and Terminology

  • Cells have a watery (aqueous) interior.
  • Organelles are membrane-bound structures within eukaryotic cells.
  • Cytoplasm is everything between the nucleus and the cell membrane.
  • Cytosol is the space within the cytoplasm, excluding membrane-bound organelles.

Eukaryotic Cell Structure

  • Nucleus: Contains DNA, enclosed by a double membrane (nuclear envelope) with nuclear pores.
  • DNA exists as chromatin (DNA wrapped around histone proteins).
  • Endomembrane System: Includes the nuclear envelope, endoplasmic reticulum (smooth and rough), and Golgi apparatus.
    • Connected through vesicles for protein transport.
  • The Golgi apparatus functions as a post office, directing proteins to various sites in the cell.

Prokaryotic vs. Eukaryotic Cells

  • Prokaryotes:
    • Single, circular DNA molecule.
    • Lack histones.
    • Reproduce by binary fission.
    • Distinct ribosomes.
  • Eukaryotes:
    • Multiple linear chromosomes.
    • Have histones.
    • Reproduce by mitosis and meiosis.
    • Distinct ribosomes.
  • Mitochondria:
    • Have their own circular DNA without histones.
    • Reproduce by binary fission.
    • Have ribosomes similar to prokaryotes.

Endosymbiotic Theory

  • Mitochondria and chloroplasts originated from bacteria engulfed by ancestral eukaryotic cells.
  • Led to the evolution of all eukaryotic life.
  • Mitochondria's main role is generating energy in the form of ATP.
    • Mitochondria are “the powerhouse of the cell.”
  • The large cell provided protection, food, and homeostasis to the engulfed bacteria.
  • Chloroplasts originated from engulfed cyanobacteria, leading to all photosynthetic eukaryotes.