🌱 TEORÍA CELULAR | Formulación y postulados | Examen UNAM | Descubrimiento de la célula | Biología

Introduction to Cell Biology

Overview of Cells

• Carlos introduces the topic of cell biology, emphasizing that cells are the basic structural and functional units of all living organisms.

• All living beings, including bacteria (single-celled) and animals/plants (multicellular), are composed of cells.

Discovery of the Cell

• The discovery of cells and the formulation of cell theory were made possible by the invention of the microscope in 1660.

• Zacharias Jansen created the first simple microscope, which consisted of a tube with two lenses, allowing for significant magnification.

Robert Hooke's Contribution

• In 1665, British scientist Robert Hooke built a more complex compound microscope to study living organisms.

• While examining cork under his microscope, Hooke discovered small cavities resembling honeycombs and named them "cells."

• It is important to note that Hooke only observed dead plant cells; he did not realize they were fundamental units of life.

Anton van Leeuwenhoek's Discoveries

• In 1670, Anton van Leeuwenhoek developed an advanced single-lens microscope and began studying various samples.

• He discovered tiny moving creatures in stagnant water, later identified as bacteria and protozoa but referred to as "animalcules" at that time.

• Van Leeuwenhoek also examined semen and was the first to observe spermatozoa.

Contributions from Robert Brown

• In 1831, Robert Brown studied plant samples under a microscope and identified a dark central area in all observed cells, which he named the nucleus.

Summary Points on Key Figures

• Zacharias Jansen: Inventor of the first microscope.

• Robert Hooke: Coined the term "cell" after observing cork; noted for discovering dead plant cells.

• Anton van Leeuwenhoek: First to observe live bacteria and spermatozoa; known as the father of microbiology.

• Robert Brown: Discovered the nucleus within plant cells.

Transition to Cell Theory

Development of Cell Theory

• By early 19th century (1838), advancements in cellular studies led to formulating cell theory based on previous discoveries.

Theory of Cell Biology

Introduction to Key Contributors

• The theory of cell biology is considered a fundamental pillar in biology, leading to many current understandings.

• In 1838, German botanist Matthias Schleiden began formulating this theory, focusing on plant studies.

• In 1839, zoologist Friedrich Schwann joined the theory, emphasizing animal studies.

• Over a decade later, in 1858, Rudolf Virchow complemented the theory with additional insights.

Postulates of Cell Theory

Anatomical Postulate

• The anatomical postulate states that all living beings are composed of cells; presented by both Schleiden and Schwann.

• If asked who proposed that all animals are made up of cells, the answer is Schwann due to his background as a zoologist.

Physiological Postulate

• The physiological postulate asserts that the cell is the basic functional unit of life; also introduced by Schleiden and Schwann.

Origin Postulate

• The origin postulate claims that all cells arise from pre-existing cells; this was proposed by Virchow.

• It emphasizes that no cell can spontaneously generate; they come from division processes.

Additional Insights on Cell Theory

Hereditary Postulate

• A fourth postulate has emerged: the hereditary postulate which states that cells contain genetic information in DNA passed from mother to daughter cells during division.