1. 4-1 Introduction to the Cell

2. Important events in the discovery of the cell and the development of the cell theory…..

3. 1665 – Robert Hooke Coined the term "cells”. Observed cells in cork.
Cork Cells

4. 1673- Anton van Leeuwenhoek
Created a powerful microscope

5. Robert Brown
-noticed that pollen grains in water jiggled around called “Brownian motion”
-discovered the nucleus
Nucleus
Human Cheek Cell

6. A botanist who concluded that all plants are made of cells.
Matthias Schleiden
A botanist who concluded that all plants are made of cells.
Typical Plant Cell

7. 1839 - Theodor Schwann A zoologist who concluded that all animals
are made of cells.
Nerve Cells

8. 1855 - Rudolph Virchow A physician who did
research on cancer cells and concluded
“Omnis cellula e cellula”.
“All cells are from other
pre-existing cells.”

9. The Cell Theory
1. All living things are composed of one or more cells.
2. Cells are the basic units of structure and function in an organism.
3. Cells come only from existing cells.

10. both in size, shape, and internal organization.
Cells are Diverse…
both in size, shape, and internal organization.

11. Why Are Cells So Small?
Transport- Cell volume to surface area ratios favor small size.
Control- Nucleus to cytoplasm consideration.
Metabolic requirements-
……..we’ll come back to this later.

12. Note: 1.0 mm = one millionth of a meter
How small can a cell be?
Mycoplasmas - bacteria that are 0.1 to 1.0 mm (1/10 the size of regular bacteria).
Note: 1.0 mm = one millionth of a meter

13. All cells have…… Plasma (cell) Membrane Nucleus (eukaryotes only)
Cytoplasm (an area)
Organelles (structures with
specialized functions)

14. Cell Types
Prokaryotes- simple cells that do not have internal membranes
example = bacteria
Eukaryotes- more complex cells that do have internal, membrane-bound structures
examples = plants and animals

15. Eukaryotic Organisms: include protists, fungi, plants and animals
Timeline
Prokaryotic
Organisms:
First appeared 3.5 BYA
include bacteria
and cyanobacteria
Eukaryotic Organisms:
First appeared 2.0 BYA
include protists, fungi, plants and animals

16. Key Differences: Eukaryotes Prokaryotes
Have a nucleus and other membrane bounded structures.
Have large ribosomes
DNA is organized into chromosomes
Flagella are made of microtubules and have a 9+2 structure
Cell walls are made of cellulose
Prokaryotes
Lack a nucleus and other membrane bounded structures.
Have small ribosomes
DNA is not organized into chromosomes
Flagella are not made of microtubules and does not have a 9+2 structure
Cell walls are made of peptidoglycan, not cellulose

17. Examples
Prokaryotic
Eukaryotic
Nucleus

18. Eukaryotic
Prokaryotic