Discovery of the Cell

1590: Zacharias Janssen

• First compound microscope

1665: Robert Hooke

• Looked at cork under the microscope

• Called the empty chambers he saw ‘cells’

1674: Matthias Schleidon

• All plants are made from cells

1839: Theodor Schwann

• All living things are made of cells

1855: Rudolf Virchow

• New cells only come from existing cells

Cell Theory

• All living things are made of 1 or more cells

• Cells are the smallest units of function and structure in life

• New cells are produced from existing cells

All cells have 4 things in common:

• Cell membrane

• DNA

• Cytoplasm

• Ribosomes

Types of Cells

Prokaryotes

• Do NOT contain a membrane-bound nucleus/organelles

• Have genetic information, but it isn’t stored in the nucleus.

• Have the 4 things in common

  • Unicellular

Example: Bacteria (only remaining prokaryote)

Eukaryotes

• Have a nucleus (contains the DNA)

• Have organelles (little organs)

  • Unicellular or Multicellular

Examples: Plants, animals, fungi, and protists

Cell Specialization

• a cell’s shape (structure) relates to what it does

Example: White blood cells change shape (fit through tight spaces and engulf invaders)

Cell Organization

Cell → Tissues → Organ → Organ System → Organism

Example: Muscle cell → smooth muscle → tissue → stomach organ → digestive system

Cell Membrane

Cell Membrane Structure

Phospholipid bilayer

Glycerol head and 2 fatty acid tails

2 layers

Cholesterol - Prevents fatty acid tails from sticking together, maintains flexibility

Carbohydrates - identify chemical signals