Entry cell section

1. Biology Opening Poll
All living things are composed of ______.
A. Cells
B. Tissues
C. Membrane- Bound Organelles
This session will be recorded for learning purposes. Learning purposes include: a lesson review for students who are
absent, students who want to review for a test, etc.

2. Science Fact of the Day
 There are 37.2 trillion cells in your body
 50,000 cells have died and been replaced while you read this science fact

3. Standards and Objectives
 B.1.5 Develop and use a model to illustrate the hierarchical organization of
interacting systems (cell, tissue, organ, organ system) that provide specific
functions within multicellular organisms.
 Students will be able to
 Compare and contrast organisms that are unicellular and multicellular.
 Compare and contrast prokaryotic cells and eukaryotic cells.
 Explain how cells were discovered and how the cell theory was developed.

4. Cells
LESSONS 3.01, 3.02 AND 3.04

5. Structural
Organization

6. History of Cells
 First compound microscope was created in 1590 by Zacharias
Janssen
 Robert Hooke discovered cells in 1665
 Examined the bark of a cork tree using a compound microscope
 Anton van Leeuwenhoek observed first living cells in 1674
 In 1838 Matthias Schleiden proposed all plants were made of
cells
 In 1839 Theodor Schwann recognized that animals were made
of cells
 In 1855 Rudolf Virchow declared that all living cells only come
from other living cells

7. Modern Cell Theory
All organisms are
made of one or
more cells.
The cell is the basic
unit of structure
and function of
living things.
All cells come from
other living cells.
 Cells contain genetic information that is passed on to the next generation of cells.
 Cells are chemically very similar.
 The flow of energy in living things occurs in cells.

8. Cell
Characteristics
 Basic unit of structure and
function of ALL living things
 Arise from existing cells
 Division or Union

9. Unicellular
 Unicellular
 Composed of a single cell
 All the characteristics of life happen
within the cell
 Ex.) Bacteria

10. Multicellular
 Multicellular
 Composed of many cells
 Each type of cell performs a specific job
(differentiated)
 Same basic internal structures
 Ex.) Humans

11. Prokaryotic Cells
 Cell that does NOT contain a nucleus or membrane
bound organelles
 DNA usually exists as a looped molecule
 Earliest life- forms on earth
 Stromatolites – fossilized rock formations of prokaryotes
dating back 3.5 billion years
Cell Membrane
DNA
Cytoplasm
Cell Wall

12. Eukaryotic Cells
 Cell contains a nucleus and other membrane
bound organelles
 DNA is contained with the nucleus
 Can be unicellular or multicellular

13. Learning Check
True or False
Prokaryotic cells ALWAYS contain a nucleus

14. Unicellular Eukaryotes
 Some eukaryotes are single celled organisms
 Ex.) yeast, amoeba, paramecium, diatom

15. Example
Classify the following organism
An amoeba is a single celled organism that contains a nucleus and membrane bound organelles.
Answer: Unicellular and eukaryotic
Archaea is a domain of single celled organisms that do NOT contain a nucleus or membrane bound
organelles.

16. Endosymbiotic Theory
 Eukaryotes arose from prokaryotes
 One prokaryotic cell may have engulfed another forming a union in which both
cells worked cooperatively
 Mitochondria and chloroplasts contain their own DNA
 Organelle DNA share many traits with bacterial DNA

17. Assignment
 10.2 Exit Ticket