Life Is Cellular

Section 7.1

Discovery of the Cell• Cells remained “out of

sight” until microscopes were invented.

• In the late 1500’s, eyeglass makers in Europe discovered that using several glass lenses in combination could magnify the smallest objects to make them easier to see.

Early Microscopes

• 1665-Robert Hooke used an early compound microscope to look at a nonliving slice of cork.

• He called the empty chambers “cells”

Early Microscopes (cont.)

• Anton van Leeuwenhoek used a single lens microscope to observe pond water and other things.

• Saw a fantastic tiny world of living things.

Electron Microscopes

• Two major types: Transmission and Scanning.

• Transmission- Form flat and 2-D images.

• Scanning- Produces 3-D images.

Exploring the Cell• Microscopes use lenses

to magnify the image of an object by focusing light or electrons.

Most familiar microscope:

Compound Light Microscope

• Using chemical stains or dyes help see the cell better.

The Cell TheoryCell Theory-1) All living things are made up of cells.

2) Cells are the basic units of structure and function in living things.

3) New cells are produced from existing cells.

Concept #1- A polar bear is made up of many cells.

Concept #3- All polar bears cells came from a single living cell. They divide and they grow to replace old dead cells.

Concept #2- Different cells in a polar bear’s body does different jobs. Example: Fat cells provide insulation and energy, white blood cells carry oxygen.

Prokaryotes and Eukaryotes• All cells are surrounded

by a thin flexible barrier called a Cell Membrane.

• Cells are divided into two categories: Prokaryotes and Eukaryotes

• The nucleus is a large membrane- enclosed structure that contains genetic material in the form of DNA.

Prokaryotes• Cells that do not

enclose DNA in nuclei.

• Mainly smaller and simpler than eukaryotic cells.

• Main examples are bacteria.

Eukaryotes• Cells that enclose their

DNA in nuclei.

• Mainly larger and more complex than prokaryotic cells.

• Most contain dozens of structures and internal membranes.

• Examples: Plant and Animal Cells