Cell Theory

And its exceptions

Background

• Invention of microscope by van Leeuwenhoek

• 1665 – Robert Hooke– Viewed cork – saw cell walls– Named them “Cells”

• Robert Brown – Saw large dark staining

structure in middle of cells– Named the “nucleus”

Cell Theory – 3 parts1. Living things are made of cells2. Cells are the basic unit of structure and function of living things– Schleiden worked with plants– Schwann worked with animals

3. Cells come from other cells–Virchow saw cells dividing

under the microscope

Exceptions1. If ALL cells come from other cells – where did the

first cell come from??????????????

2. What about viruses????- Not made of cells- Don’t do GRRSNERT- NOT living

Last Exception3. Mitochondria and Chloroplasts

- Have their own DNA (separate from nucleus)- Can reproduce independently from the rest of the

cell- Did they once live on their own????

Cells Vary in Shape because they vary in Function – made of

different proteins

Why are Cells small?Smaller is more efficient

Larger requires more ENERGY