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 thatmakes 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): (Greek): – karuonkaruon – “kernel” – “kernel”– eueu – “true” – “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.– propro – “before” – “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.