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.
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Discovery of Discovery of CellsCells
First to View CellsFirst 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 LeeuwenhoekAnton 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 THEORYCELL THEORY•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)
NEED TO KNOW!!! NEED TO KNOW!!!
Cell ClassificationCell Classification
• Prokaryotes– NO Membrane
bound organelles
– NO nucleus– Bacteria
• Eukaryotes– Most cells– True nucleus– Membrane
bound organelles
– Plants, fungi, animals
ProkaryotesProkaryotes• Simplest type of cell
• Lack a nucleus or membrane bound organelles
• Single, circular chromosome
• Bacteria and Archaebacteria
ProkaryotesProkaryotes• DNA located in the
center
• Cell membrane AND cell wall
• Ribosomes to make proteins
• May have cilia/pilli/flagella to aid in movement
EukaryotesEukaryotes
• HAVE a nucleus and membrane bound organelles
• Protists, fungi, plants, and animals
• Larger and more complex type of cells
EukaryoticEukaryotic CellCell
• Nucleus that contains DNA
• Cell membrane
• Specialized organelles– Where chemical
reactions occur
Number of Cells• Unicellular Organisms
– Organism is only one single cell
• Multicellular Organisms– Complex organisms with cells
organized into tissues, organs, systems
Looking at Cells 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
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