The Cell

Discovery of the Cell In 1665, an English scientist named Robert Hooke looked at a thin piece of cork. He observed that it was made of thousands of tiny empty chambers. They looked like rooms in a monastery, called cells. So, the term cell was given to describe these tiny units in living matter.

Other Scientists With Similar Findings Anton van Leewenhoek of Holland observed pond water, and found tiny living organisms. German biologists Matthias Schleiden and Theodor Schwann concluded that plants and animals were made of cells in the mid 1800’s. Rudolph Virchow concluded that new cells could only be produced from existing cells. These findings led the science community to form a theory. What is this theory called?

The Cell Theory States that: All living things are composed of cells. Cells are the basic units of structure and function in living things. New cells are produced from existing cells.

Exploring the Cell Today scientists use highly technical methods to observe the cell. Confocal light microscopy- scans with a laser beam. High resolution video technology can show cells growing and dividing. Electron microscopes can magnify images up to 1000 times those of light microscopes.

Basic Cell Structure Cells are all different sizes and shapes, but all have 2 things in common: 1. Contain a cell membrane 2. Contain DNA which carries genetic information.

Two Categories of Cells Cells are divided into 2 groups depending on if they have a nucleus or not. The nucleus is a membrane enclosed structure that contains DNA The 2 groups are: Prokaryotes – contain no nucleus. Eukaryotes – contain a nucleus.

Eukaryotic Cell Structure The eukaryotic cell can be compared to a factory, with many structures that perform different jobs, and whose overall purpose is, sustaining life. The eukaryotic cell is divided into 2 main parts: the nucleus and the cytoplasm.

The Nucleus The nucleus is the control center of the cell, in the way the main office controls the factory. It contains DNA with coded instructions for making proteins and other important molecules.

The Cytoplasm A jelly-like substance containing all organelles including: Ribosomes Endoplasmic Reticulum(rough & smooth) Golgi Apparatus Lysosomes Vacuoles Mitochondria Chloroplasts Cytoskeleton Centrioles

Each organelle has a specific function, just like a factory has many different kinds of machines that each perform different jobs.