1. Cells: The Basic Units of Life
Section 1: The Diversity of Cells

2. What is a cell?
The smallest unit that can perform all the processes necessary for life.
Brainstorm with your neighbor what you think some of those processes are?
Why do you think cells weren’t discovered until the mid-1600’s
Possibilities: growing, reproducing, taking in nutrients, getting rid of waste, performing specialized functions (heart cells, nerve cells)
Answer: That was when the microscope was invented.

3. Scientists who first discovered and defined cells
First person to describe cells First person to discover single-celled organisms, different blood cells and bacteria. People who wrote the 3 parts of the cell theory
Robert Hooke
Anton van Leeuwenhoek
Schleiden/Schwann/Virchow

4. Robert Hooke Drawing

5. The Cell Theory All organisms are made of cells
The cell is the basic unit of all living things
All cells come from existing cells

6. Cell Size Most cells are small.
Big cell example: chicken egg yolk
The surface area-to-volume ratio limits size
If cell volume is too big then the surface area will be too small for sufficient nutrient and waste transfers.
Equation: Surface area ÷ volume
Challenge question: What is the surface area-to-volume ratio of a cube whose sides are 2 cm long?

7. Cell parts
All cells have the following even though they have different functions and different shapes
Cell Membrane
Cytoplasm
Organelles
Genetic material

8. Cell Membrane & Cytoplasm
Protective layer that covers the cell’s surface
Acts as a barrier
Controls materials going in and out of the cell
Cytoplasm
The fluid inside the cell

9. Organelles Structures that have specific functions in the cell.
Different types of cells have different organelles
Examples: nucleus, ribosomes, mitochondria, endoplasmic reticulum, chloroplasts

10. Genetic Material All cells have DNA (deoxyribonucleic acid)
Genetic material passed from parent to new cells
Contains information needed to make new cells
Controls the activities of the cell
Is enclosed in the nucleus is some cells

11. Two Basic types of cells
Prokaryotes: cells without a nucleus
Eukaryotes: cells with a nucleus

12. Prokaryotes Two groups Eubacteria(or just plain bacteria)
Most common
World’s smallest cells
Archaebacteria
Same in many ways to bacteria
Some organelles are different
Can live where no other organism can (hot springs or deep ocean volcanic vents)

13. Eukaryotes All living things that are not prokaryotes are eukaryotes
Are the largest cells (10x larger than bacteria)
Have a nucleus
Can be single-celled organisms
Examples: amoebas and yeasts
Often are multicellular organisms
Examples: animals or plants

14. Review question 1 Who was the first person to describe cells?
Louis Pasteur
Charles Darwin
Robert Hooke
Isaac Newton

15. Review question 2
Which of the following is NOT part of the cell theory?
All organisms are made of cells
The cell is the basic unit of all living things
All cells are the same shape
All cells come from existing cells

16. Review question 3 Which cell part acts as a protective barrier?
Cell Membrane
Cytoplasm
Organelles
Genetic material

17. Review question 4 Which type of cell has a nucleus? Prokaryote
Eukaryote