Cell Theory

- Outline the cell theory.

- Discuss the evidence for the cell theory.

Learning Objectives

O O O To summarize scientists’ contributions to the development of cell theory and the rejection of spontaneous generation.

To outline cell theory.

To discuss the evidence for cell theory.

Spontaneous Generation

O O O Early scientists based many of their theories on life without experimentation to test them.

Most scientists concluded that non-living things could be transformed into living things.

Abiogenesis (spontaneous generation) was widely accepted until the 17 th century.

Examples of Abiogenesis

O O Rotting meat will eventually turn into maggots A dirty shirt and wheat will be transformed into mice

O O O O O O O

What do we believe now?

Break into inquiry groups of seven.

I will number you from one to seven.

Based on your number, you will research a scientist who contributed to the development of cell theory.

You will become an expert on that scientist and his contributions.

As a group of experts develop a list of facts, a summary about your scientist.

You will use the class research for your homework.

Your homework: write a summary paragraph, describing how knowledge about the cell theory was developed from 1590 – 1855.

Scientist’s names

1.

2.

3.

4.

5.

6.

7.

Zacharias Jansen Robert Hooke Antonie van Leeuwenhoek Mathias Schleiden Theodor Schwann Jan Evangelista Purkinje Rudolf Virchow

What do we believe now?

Cell Theory Overview

Timeline leading to Cell Theory 1590 Jansen

- microscope

~~ 1665 Robert Hooke

- first person to use the term "cell" to describe a form of life

1675 Antonie Van Leeuwenhoek

- Discovered bacteria

~~ 1838 1839 1840 1855 Schleiden

- discovered / proved that all plants are made of cells

Theodor Schwann

- Discovered the digestive enzyme "pepsin"

Jan Purkinje

- "protoplasm"

Rudolph Virchow

- Statement of the cells in proposal of "the cell theory"

Onion Cells & Cheek Cells

O O O O You will prepare a wet mount of an onion cell and cheek cell.

Follow the lab instructions.

Make sure the microscope is on low power when you put the slide on.

Don’t use too much iodine!