Cell and Molecular Biology Study Notes

Gene Expression in Human Brain Cells

  • Study by Soojin Yi, Dennis Joshy, and Gabriel Santepere

    • Focus on evolution of genes in brain cells compared to chimpanzees

    • Findings: Human brain cell genes are more productive than those in other primates.

Cell Biology

  • Definition: Study of life at the cellular level.

  • Cells: Simplest units of life.

Phylogenetic Tree of Life

  • Classification of life forms:

    • Bacteria

    • Archaea

    • Eucarya (Eukaryotes)

    • Includes plants, animals, fungi, etc.

Model Organisms in Cell Biology

  • Commonly used organisms:

    • Bacteria: Escherichia coli (E. coli)

    • Fungi: Saccharomyces cerevisiae (brewer's yeast)

    • Plants: Arabidopsis thaliana

    • Animals:

    • Drosophila melanogaster (fruit fly)

    • Caenorhabditis elegans (nematode)

    • Xenopus laevis (African clawed frog)

    • Mus musculus (house mouse)

    • Homo sapiens (humans)

Historical Development of Cell Biology

  • Anton van Leeuwenhoek (1673): First to view living organisms.

  • Robert Hooke: Named cells due to their resemblance to monk cells.

    • Contribution to the understanding of cell structure and microscopy.

Development of Biochemical Strands

  • Key figures:

    • Friedrich Wohler: First synthesized urea from inorganic material (1828).

    • Louis Pasteur: Discovered role of microorganisms in fermentation.

    • Eduard Buchner: Proved that cell extracts could ferment substances.

Cell Theory Development

  • Matthias Schleiden & Theodor Schwann:

    • Postulated that all living organisms are composed of cells.

  • Rudolph Virchow (1855): Concluded all cells arise from pre-existing cells.

    • Key phrase: "Omnis cellula e cellula".

  • Understanding of cell division still incomplete during this time.

Spontaneous Generation Theory

  • Historical belief that life arises spontaneously from non-living matter.

  • Examples included flies from manure, mice from dirty cloth, etc.

Advancements in Cell Biology Techniques

  • Keith Porter & Sjostrand: Developed methods for electron microscopy, revealing structures like cytoskeleton and endoplasmic reticulum.

  • Robertson (1957): First to observe trilaminar appearance of membranes.

  • Singer & Nicolson (1972): Proposed fluid mosaic model of membrane structure.

Emergent Properties of Life

  • Definition: Properties that emerge at higher organizational levels.

  • Life is considered an emergent property arising at the cellular level.

Endosymbiotic Theory

  • Proposed by Lynn Margulis (1970): Eukaryotic cells evolved from prokaryotic cells through symbiosis.

  • Supported by organelles like chloroplasts and mitochondria having their own DNA.

Key Features of Cell Structure

  1. Cell Membrane: Boundary between exterior and interior.

  2. Cytoplasm: Aqueous interior organized into compartments.

  3. Macromolecules: Required for cellular functions.

  4. Energy: Essential for maintaining and creating cellular structures.

  5. Information: DNA provides instructions for cellular organization.

Levels of Biological Organization

  • CELL: Basic unit of all organisms.

  • TISSUE: Groups of cells working together.

  • ORGAN: Structures like heart or brain.

  • ORGAN SYSTEMS: Groups of organs working together (e.g., respiratory system).

  • ORGANISM: Complete individual.

  • Higher levels: POPULATION, COMMUNITY, ECOSYSTEM, BIOME, BIOSPHERE.

Characteristics of Organisms

  • Made of cells, require energy, reproduce, maintain homeostasis, organized, respond to environment, grow and develop, exchange materials with surroundings.