1. Cell Theory

2. Cell Theory Understanding of cells required Improvement of microscopes
Hundreds of years of research and observations
The Cell Theory states
All living things are made of cells
Cells are the basic units of structure and function in living things
Cells come from pre-existing cells

3. Exceptions to cells theory
Where did the first cell come from?
Viruses: non-living genetic material; need to act as parasites to reproduce
Mitochondria and chloroplasts have their own DNA; partially reproduce on their own

4. Cell Theory Timeline
1590s: Zacharias Janssen worked with his father and invented the first compound microscope 1665: Robert Hooke observes cork under a microscope and names the tiny boxes he saw “cells” 1673: Anton von Leeuwenhoek observed single-celled organisms and blood cells

5. Cell Theory Timeline
1801: Robert Brown discovers the nucleus of the cell
1838: Matthias Schleiden (ShLY-dun) says all plants are made of cells
Theodor Schwann says all animals are made of cells
1855: Rudolph Virchow (FUR-koh)says cells only come from other cells

6. Cell scale
cell scale

7. Levels of organization
Cells: Smallest structural and functional unit of an organism
E.g. Skin cells, Nerve cells
Tissues: a group of similar cells that perform particular functions
E.g. Nerve, muscle, connective, epithelial
Organs: groups of tissues working together
E.g. Heart, Kidney
Organ systems: a group of organs working together
E.g. Digestive system, nervous system

8. Basic Cell Structure
The cell membrane: A thin, flexible barrier around the cell.
Cell wall: Many cells also have a strong layer around the cell membrane.
Cell membranes and cell walls support and protect cells, while allowing them to interact with their surroundings

9. Basic Cell Structures
Nucleus (plural: nuclei): A large structure that contains the cell’s genetic material and controls the cell’s activities.
The cytoplasm: The material inside the cell membrane but not including the nucleus. The cytoplasm contains many important structures.

10. Two basic cell types
1. Prokaryotic (Pro=before, karyon=nucleus) a. no nucleus or organelles except ribosomes b. unicellular (one-celled) c. e.g. bacteria
Anthrax
Strep throat
E. coli

11. Two basic cell types
2. Eukaryotic (True nucleus) a. have a nucleus and organelles b. unicellular and multicellular c. e.g. animals, plants, fungi, protists
yeast
Ameba, a protists

13. Prokaryotic Vs. Eukaryotic