The Cell Theory

Obj: 1. Identify the 3 parts of the cell theory

2. Explain how a specific scientist contributed to the cell theory

What is a Cell?

• Smallest basic unit of all living things• Organisms are either:– Unicellular—made of one cell such as bacteria or

amoebas– Multicellular—made up of many cells such as

plants and animals

The Cell Theory

• All living things are made of cells• Cells are the smallest basic unit of life• All cells arose from pre-existing cells

Contributors

• Robert Hooke– Discovered cells in cork in 1665

• Anton van Leuwenhoek– Father of microscopy– Discovered single organisms (in pond water) in 1673

• Schleiden and Schwann (1838 and 1839)– Schleiden—plants are made up of cells– Schwann—animals are made up of cells

• Rudolf Virchow (1855)– All cells came from other cells

Prokaryotes

• Pro—before• Kary—nucleus• Prokaryotes=before a true nucleus– No membrane bound organelles (just ribosomes)– No nucleus– Smaller than eukaryotic cells– Came before eukaryotes– Single stranded and circular DNA– All bacteria are prokaryotes

Eukaryotes

• Eu—true• Kary—nucleus• Eukaryotes=have a true nucleus– Nucleus with a nuclear envelope– Bigger and more complex than prokaryotes– Have membrane bound organelles– Double stranded DNA in form of chromosomes– Can be uni or multicellular– Examples: animals, plants, fungi

Similarities

• Contain all 4 biomolecules (carbs, lipids, proteins and nucleic acids)

• Ribosomes• DNA• Metabolism• Can be unicellular• Have plasma membrane or cell wall