Discovery of Cells

First to View Cells In 1665, Robert Hooke used a microscope to examine a thin slice of cork What he saw looked like small boxes so he called them “cells”

Anton van Leeuwenhoek In 1673, Leeuwenhoek was first to view organisms under a microscope He looked at pond water & plaque he scraped from his teeth

Development of Light Microscope Leeuwenhoek was the first scientist to describe living cells as seen through a simple microscope Simple Light Microscope - One lens and uses natural light Compound Light Microscope - More than one lens to magnify Magnifies up to 1500 times.

CELL THEORY All living things are made of cells NEED TO KNOW!!! NEED TO KNOW!!! All living things are made of cells Cells are the basic unit of structure and function in an organism (basic unit of life) Cells come from the reproduction of existing cells (cell division)

Cell Classification Prokaryotes Eukaryotes NO Membrane bound organelles NO nucleus Bacteria Eukaryotes Most cells True nucleus Membrane bound organelles Plants, fungi, animals

Prokaryotes Simplest type of cell Lack a nucleus or membrane bound organelles Single, circular chromosome Bacteria and Archaebacteria

Prokaryotes DNA located in the center Cell membrane AND cell wall Ribosomes to make proteins May have cilia/pilli/flagella to aid in movement

Eukaryotes HAVE a nucleus and membrane bound organelles Protists, fungi, plants, and animals Larger and more complex type of cells

Eukaryotic Cell Nucleus that contains DNA Cell membrane Specialized organelles Where chemical reactions occur

Number of Cells Unicellular Organisms Multicellular Organisms Organism is only one single cell Multicellular Organisms Complex organisms with cells organized into tissues, organs, systems

Looking at Cells A cell’s shape reflects its function Can be long and flat, branched, round, etc Cell size is limited by the cell’s surface area to volume ratio The larger the cell, the more nutrients it needs and waste it produces