Cell Biology test 1

Define a cell.

• A ___ is a highly organized compartment bounded

by a plasma membrane that contains concentrated

chemicals in an aqueous solution.

• A ___ is the fundamental unit of all life.l life.

Describe Cell Theory.

Addresses 2 Fundamental Questions:

-What are organisms made of? CELLS

-Where do they come from? PRE-EXISTING CELLS

Robert Hooke

In 1665, he was the first person to use the term “cell” after observing cork under a microscope.

Anton van Leeuwenhoek

In 1674, he improved microscope lenses and observed living cells (like bacteria and protozoa), which he called “animalcules.”

Robert Brown

In 1831, he was the first to discover the cell nucleus.

Matthias Schleiden

In 1838, he concluded that all plants are made of cells and was the first to recognize cells as fundemental units of life.

Theodor Schwann

In 1839, he was the first to conclude that all animals are made of cells.

Rudolf Virchow

In 1855, he proposed that all cells come from pre-existing cells, supporting the third principle of Cell Theory.

Louis Pasteur

In 1860, he conducted a famous experiment in the 1860s that disproved the idea of spontaneous generation (the belief that life could arise from non-living matter).

Louis Pasteur’s Experiment

• He used swan-neck flasks filled with broth.

• The flasks were boiled to kill any existing microbes (sterilization).

• The unique swan-neck shape allowed air in but prevented microbes from reaching the broth.

• As long as the flask remained upright and unbroken, no microbial growth occurred.

• If the flask was tilted or the neck broken, microbes entered and growth occurred.

Louis Pasteur’s Conclusion

Microorganisms come from other microorganisms in the environment, not from non-living matter. This strongly supported the idea that cells only come from other cells, aligning with Cell Theory.

Cell biology is a multidisciplinary science that studies cells and how they function. It combines:

• Biochemistry – Study of chemical processes in cells (like enzymes, proteins, metabolism).

• Cytology – Study of cell structure and appearance (usually under a microscope).

• Genetics – Study of DNA, heredity, and how traits are passed on through cells.

Light microscopes

allowed early scientists to see cells.

Electron microscopes

(developed in the 20th century) revealed much more detail, like organelles and even viruses.

Staining techniques

Help visualize structures within cells.

DNA sequencing, CRISPR, fluorescence microscopy, and live cell imaging

Modern technologies that let scientists observe and manipulate cells at the molecular level.