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 Theory Cell 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