Discovery Cells Chapter 2, Section 3 Mrs. Fletcher’s 7 th Grade Life Science

An Overview of Cells  Cells are the basic units of structure and function in living things.

Cells and Structure  What is a cell made of and how are its parts put together?  The structures of living things are determined by the amazing variety of ways in which cells are put together.  Examples: Tree bark is different than the inside trunk (wood) or leaves because of the different ways the cells are put together.

Cells and Function  Functions are the processes that take place inside a cell to enable (help) it to stay alive and reproduce.  Some different types of functions include getting food, getting oxygen, getting rid of waste, and growing.

Many and Small  No one knew cells existed until the late 1600’s.  They were not visible with just the eye. (Too small to see).  Now we know that everything we are, everything that makes up a living organism is made of cells working together - in some cases, many, many, many cells.

First Observations of Cells  The invention of the microscope made it possible for people to discover and learn about cells.  Microscope: An instrument that makes small objects look larger. (Makes things visible that cannot be seen by the naked eye).

Robert Hooke  English scientist and inventor – built his own compound microscope in  One of the first people to observe cells looking at a thin slice of cork (a thin slice of bark from the cork tree).  He referred to the tiny empty spaces he saw as “cells” which means “small rooms.”  I guess you could say he discovered them and named them.

Anton van Leeuwenhoek  A Dutch businessman who sold clothes.  He also built simple microscopes  his simple microscope which used only one lens could magnify a specimen up to 266 times.  He viewed drops of lake water, scrapings from teeth and gums, and water from rain gutters. He discovered many different kinds of unicellular organisms which could move around. He called them “animalcules” meaning little animals.

Development of The Cell Theory  Schleiden, Schwann, and Virchow  1838 – Matthias Schleiden concluded that all plants were made of cells.  1839 – Theodore Schwann concluded that all animals are also made up of cells. This lead to all living things are made up of cells.  In 1855, Rudolf Virchow proposed that new cells are formed only from cells that already exist. “All cells come from cells.”

What the Cell Theory Says  Cell Theory – a widely accepted explanation of the relationship between cells and living things.  Cell Theory states:  All living things are composed of cells.  Cells are the basic structure and function in living things.  All cells are produced from other cells.

Summary: Complete a timeline for you binder which shows the following: 1. When the first microscope was invented and by whom. 2. Who was Robert Hooke? What did he do and when? 3. Who was Anton Van Leeuwenhook? What did he do and when? 4. Who was Matthias Schleiden, Theodor Schwann, and Rudolf Virchow? What did they do and when? 5. Due tomorrow at the beginning of class.