3.1 Cell Theory LEQ: How do enzymes help cells perform chemical reactions? LEQ: What is the cell theory? Reading: 3.1, 3.3 Activator: Cells carousel List one fact about a cell and pass the paper to the next group member. First letter of the name earliest in alphabet A-Z goes first! Key terms – cell, eukaryote, prokaryote

3.1 Cell Theory UNIT CONCEPT Cells are chemical systems with emergent properties.

3.1 Cell Theory The Cell theory has three principles. – –1) All organisms are made of at least one cell. – –2) All existing cells are produced by other living cells. – –3) The cell is the most basic unit of life. Nothing simpler is considered a living system

3.1 Cell Theory All cells have a common origin in the history of life. All cells share certain characteristics. – –*most are microscopic. – –enclosed by a membrane. – –filled with cytoplasm. – –DNA – –Ribosomes: Molecular organelle that makes proteins Bacterium (colored SEM; magnification 8800x) cell membrane cytoplasm

3.1 Cell Theory Cells can be categorized based on the presence of certain structures. Eukaryotic cells have a nucleus: –(Greek): –karuon – “kernel” –eu – “true” nucleus cell membrane organelles

3.1 Cell Theory Cells can be categorized based on the presence of certain structures: prokaryotic cell types do not have a true nucleus. –pro – “before” Obsolete term? nucleus cell membrane organelles

3.1 Cell Theory Questions: How do prokaryotic and eukaryotic cells differ?

3.1 Cell Theory Answers: Eukaryotic cells have a nucleus and membrane-bound organelles; prokaryotic cells generally do not.