Unit One Notes

CELLS – THEORY

Unit One Notes

THE FIRST OBSERVED CELLS Robert Hooke (1665) – a British

scientist who used a homemade microscope

Hooke looked at a piece of cork from the bark of an oak tree

It looked like the small rooms monks lived in at that time, so he named them Cellulae, which means “little room” in Latin

He could not see animal cells because they did not have a cell wall

Interesting fact – all known portraits of Hooke were destroyed in part because of an ongoing fued with Isaac Newton

SEEING CELLS IN OTHER LIFE FORMS

LEEUWENHOEK – IN 1673, THIS DUTCH MERCHANT WHO WAS INSPIRED BY HOOKE LOOKED AT POND SCUM UNDER THE MICROSCOPE. HE ALSO LOOKED AT GOOP SCRAPED OFF OF TEETH.

HE WAS THE 1ST PERSON TO SEE BACTERIA (CALLED THEM WEE BEASTIES), AND REALIZE THAT ANIMAL CELLS WERE DIFFERENT FROM PLANT CELLS

Cell Theory

A fundamental idea of modern biology:

The three principles of the cell theory state:1. All living organisms are

composed of one or more cells2. Cells are the basic unit of

structure and organization of all living organisms (basic unit of life)

3. Cells arise only from existing cells, with cells passing copies of their genetic material on to their daughter cells. (cells make more cells)

Two Types of Cells

Cells come in different shapes and sizes based on the function they perform.

Cells have been grouped into 2 broad categories based on their internal structures:

Prokaryotic Eukaryotic (these are

generally 1-100x larger)

Prokaryotic Eukaryotic

Cells without a nucleus

Example: Bacteria

Cells with a nucleus and other membrane bound structures. (Plant and animal cells)

Two Major Types of Cells

Plant Cells Animal Cells

Have Cell WallsA Large VacuoleChloroplasts

Have a Cell Membrane

Small VacuolesNo Chloroplasts

Eukaryotic Cells

Eukaryotic Cells cont. Eukaryotic cells are larger and

more complex Have specialized internal

structures – called organelles (like a nucleus)

Most multicellular organisms are eukaryotes (although some unicellular organisms like yeast are eukaryotes)

Eukaryotic cells have specialized functions (you have over 200 types of cells)

Believed to have evolved from prokaryotes; has led to cell diversity that helps organisms better adapt to their environments.

Inner Life of a Cell

The Inner Life of the Cell (full version).mp4 [www.keepvid.com].3gp