1. Happy Friday!
I have placed notecards on all the tables. Please take one and put your name on it. Hold onto it until the end of class.
Copy down the following homework in your calendars/planners:
Chapter 4, Sections 1 & 2 Outline due Monday, 9/18
Chapter 4, Sections 3 & 4 Outline due Friday, 9/22
Today: -Quick overview of Unit 1 Test
-Cell History/Prokaryotes vs. Eukaryotes

2. Cell History/Prokaryotes vs. Eukaryotes
Objectives
After today’s lesson you will be able to…
Identify the five scientists who contributed to our understanding of cells and the specific contributions of each
State the components of the cell theory
Distinguish between prokaryotic and eukaryotic cells by comparing and contrasting their structures

3. But First… Let’s talk about the test Your class average
Commonly-missed questions

4. Early Contributors
Robert Hooke - The first person to see cells, he was looking at cork and noted that he saw "a great many boxes.” (1665) *Interesting story of why he called them “cells”
Anton van Leeuwenhook - Observed living cells in pond water, which he called "animalcules" (1673)
Theodore Schwann - zoologist who observed that the tissues of animals had cells (1839)
Mattias Schleiden - botanist, observed that the tissues of plants contained cells ( 1845)
Rudolf Virchow - also reported that every living thing is made of up vital units, known as cells. He also predicted that cells come from other cells.

5. THE CELL THEORY
1. Every living organism is made of one or more cells. 2. The cell is the basic unit of structure and function. It is the smallest unit that can perform life functions. 3. All cells come from preexisting cells.

6. Cell Features Cells vary greatly in their size and shape.
However, all cells share common structural features, including a cell membrane, cytoplasm, ribosomes, and DNA.
Cell membrane (plasma membrane) - the outer layer that covers a cell’s surface and acts as a barrier between the outside environment and the inside of the cell.
Cytoplasm - region of the cell that is within the plasma membrane and includes fluid, the cytoskeleton, and organelles (function is to hold all those components)

7. Ribosomes - cellular structures that make proteins.
DNA – macromolecule (nucleic acid) that provides instructions for making proteins and contains all of an organism’s genes

8. Two Basic Types of Cells
Cells may be prokaryotic or eukaryotic.
Prokaryotes
Eukaryotes
Bacteria
Animals
Archaea*
Plants
Fungi
Protists**
*Archaea are a group of organisms who typically love extreme environmental conditions (i.e., very salty, very hot, highly acidic). You don’t need to know much about these right now, but do know they are a type of prokaryote.
**Protists can be multicellular OR unicellular. Examples include amoeba and paramecium. Just know these are types of eukaryotes.

10. Prokaryotic Cells Prokaryotes are/have: Very simple cells
Plasma membrane (sometimes a cell wall)
Cytoplasm
Circular “loop” of DNA
Ribosomes
Unicellular
Prokaryotic cells do not contain membrane-bound organelles or nucleus
The word "prokaryote" means "before the nucleus"

11. (b) A thin section through the
bacterium Bacillus coagulans
(TEM)
Pili: attachment structures on
the surface of some prokaryotes
Nucleoid: region where the
cell’s DNA is located (not
enclosed by a membrane)
Ribosomes: organelles that
synthesize proteins
Plasma membrane: membrane
enclosing the cytoplasm
Cell wall: rigid structure outside
the plasma membrane
Capsule: jelly-like outer coating
of many prokaryotes
Flagella: locomotion
organelles of
some bacteria
(a) A typical
rod-shaped bacterium
0.5 µm
Bacterial chromosome

12. KEY POINTS Prokaryotic cells
Do not contain a nucleus or other membrane-bound organelles
Have their circular DNA located in a region called the nucleoid
Unicellular
Smaller and simpler than eukaryotic cells

13. EUKARYOTIC CELLS The eukaryotic cell is composed of 4 main parts:
1. Cell Membrane - outer boundary of the cell
2. Cytoplasm - jelly-like fluid interior of the cell
3. Nucleus - the "control center" of the cell, contains the cell's DNA (chromosomes)
4. Membrane-Bound Organelles – specialized "little organs" that carry out cell functions

14. KEY POINTS Eukaryotic cells
Contain a nucleus and other membrane-bound organelles
Have their linear DNA located in the nucleus
Can be multicellular (plants, animals, some fungi) OR unicellular (protists, some fungi)
Larger than prokaryotic cells