History of Cell Theory

People

• Robert Hooke (1665)- Came up with word "cells" after looking at a cork under a microscope.
• Anton van Leeuwenhoek (1667)- made microscopes; looked at animalcules from pound water.
• Schleiden (1838)- "plants are made out of cells"
• Schwann (1839)- "animals are made out of cells"
• Virchow (1855)- "cells only come from pre-existing cells"

1. All organisms are composed of cells
2. Cells are the basic unit of life
3. Cells arise only from pre-existing cells

Cell size is limited by diffusion time.

Surface area-to-volume ration.

Prokaryotic- 1-10 nanometers

Eukaryotic- 10-100 nanometers

Membrane-bound structures

Types:

Large central vacuole in plant cells

Contractile Vacuole in some protists

Food or storage vacules

Mitochondrion

[image]

Site of cellular respiration (ATP)

In almost all eukaryotic cells

Contain their own DNA and Ribosomes

Chloroplasts

[image]

Site of photosynthesis

in cells of green plants and some protists (algae)

Contains their own DNA and ribosomes

• Eukaryotic organelles evolved through symbiotic relationships
• One cell engulfed a smaller cell
• Mitochondria and choroplasts

Actin filaments- cellular contractions, crawling, "pinching"

Microtubules- organization and moves materials

Intermediate filaments- Structural stability

Crawling movement- Actin/myosin

Flagella and cilia

• Microtubules
• undulation. not rotation

Function is to support and protect

Plants- cellulose

Fungi- chitin

Protist- variable or absent

Animals- none

Bacteria- peptidoglycan

Surrounds animal cell

glycoproteins and fibrous proteins such as collagen

connected to cytoskeleton via membrane proteins