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Part 1: The Cell Theory
Photo Credit: © Quest/Science Photo Library/Photo Researchers, Inc.
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2. The Discovery of the Cell
In 1665, Robert Hooke used an early microscope to look at a thin slice of cork, a plant material.
Cork looked like thousands of tiny, empty chambers.
Hooke called these chambers “cells.” (THINK PRISON CELLS)
Cells are the basic units of life.
Hooke’s Drawing of Cork Cells
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3. Anton van Leeuwenhoek used a microscope to observe tiny organisms (microorganisms) in pond water

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The Cell Theory
In 1838, Matthias Schleiden concluded that all plants were made of cells.
In 1839, Theodor Schwann stated that all animals were made of cells.
These conclusions led to the first two parts of the cell theory:
1) All living things are composed of cells
2) Cells are the basic unit of structure and function in living things
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5. The Cell Theory In 1855, Rudolph Virchow concluded that new cells
were created only from division of existing cells.
This led to the third part of the cell theory:
3) New cells are produced from existing cells

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Exploring the Cell
Electron Microscopes
Electron microscopes reveal details 1000 times smaller than those visible in light microscopes.
Electron microscopy can be used to visualize only nonliving, preserved cells and tissues.
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Exploring the Cell
Transmission electron microscopes (TEMs)
Used to study cell structures and large protein molecules
Specimens must be cut into ultra-thin slices
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Exploring the Cell
Scanning electron microscopes (SEMs)
Produce three-dimensional images of cells
Specimens do not have to be cut into thin slices
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Exploring the Cell
Scanning Electron Micrograph of Neurons
Photo Credit: © Dr. Dennis Kunkel/Phototake
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10. Prokaryotes and Eukaryotes
Cells come in a variety of shapes and sizes.
2 Types: Prokaryotic and Eukaryotic
All cells:
are surrounded by a barrier called a cell membrane.
at some point contain DNA.
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11. Prokaryotes and Eukaryotes
Cells are classified into two categories, depending on whether they contain a nucleus.
The nucleus is a large membrane-enclosed structure that contains the cell's genetic material in the form of DNA.
The nucleus controls many of the cell's activities. (The Brain of the Cell!)
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Eukaryotes are cells that contain nuclei.
Prokaryotes are cells that do not contain nuclei.
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What are the characteristics of prokaryotes and eukaryotes?
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Prokaryotes 
Prokaryotic cells have genetic material that is not contained in a nucleus.
Prokaryotes do not have membrane-bound organelles (cell parts surrounded by membrane).
Prokaryotic cells are generally smaller and simpler than eukaryotic cells.
Example Organism: Bacteria
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Eukaryotes 
Eukaryotic cells contain a nucleus in which their genetic material is separated from the rest of the cell.
Eukaryotic cells generally contain dozens of cell parts (organelles) and internal membranes
They are generally larger and more complex than prokaryotic cells.
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17. Cells contain internal structures called organelles
Organelles carry out specific functions for the cell (like organs in the body!)

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Many eukaryotic cells are highly specialized (Ex: leaf cells in plants, nerve cells, muscle cells)
Example Organisms: Plants, animals, fungi, and protists are eukaryotes.
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19. Just for Fun Guess the cell type for each cell: Options are:
plant cell, neuron (nerve cell), skin cell, sperm cell, bone cell, bacterium, blood cell, muscle cell

20. #2 #1 #3

21. #4 #5 #6

22. #7 #8

23. How are Cells Different From Each Other?
Size
Shape
Internal Organization
Fun Fact: In the human body, there are at
least 200 different cell types!

24. Size Big Enough for the Unaided Eye?
Example: Giraffe Nerve Cells (2 Meters)
Small Enough to Need a Microscope?
Examples:
1) Plant / Animal Cells ( Micrometers)
2) Bacteria (0.2 Micrometers)

25. Shape Remember: Form Follows Function!
Question: How does the shape of these cells help them perform their functions?

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Part 2: Eukaryotic Cell Structures
Photo Credit: © Quest/Science Photo Library/Photo Researchers, Inc.
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27. Review
Organelle: A cell component that performs specific functions for the cell
Cell biologists divide the eukaryotic cell into two major parts: the nucleus and the cytoplasm.
The Cytoplasm is the portion of the cell outside the nucleus.

28. Cytoplasm
Definition: The region of a cell between the cell membrane and the nucleus
Contains a variety of organelles in a jelly-like, watery fluid called the cytosol

30. Cell Membrane Also called the plasma membrane
A barrier that surrounds the cytoplasm
Separates the inside of cells from the outside environment
Regulates passage of materials into and out of the cell
Found in both plant and animal cells

32. Nucleus The nucleus is the control center of the cell.
The nucleus contains nearly all the cell's DNA and with it the coded instructions for making proteins and other important molecules.

33. Red = Nucleus
Green = Nucleolus

34. Ribosomes
One of the most important jobs carried out in the cell is making proteins.
Proteins are assembled on ribosomes.
Ribosomes are small particles of RNA and protein found throughout the cytoplasm.

36. Endoplasmic Reticulum
A system of membranous tubes and sacs
Used to make proteins and as a “highway for cell materials”

37. Rough ER
Smooth ER
Structure
Has Ribosomes
No Ribosomes
Function
Makes Protein
Regulates calcium level in muscle, makes steroids in glands, breaks down toxins in liver

39. Golgi Apparatus
Function: the processing and packaging organelle; works with the ER; modifies proteins to be sent out of the cell
Structure:
1) System of membranes
2) Flattened sacs

42. Lysosomes
Structure: small, spherical organelles that enclose hydrolytic enzymes within single membranes
Function: these enzymes can digest carbs, lipids, DNA, RNA, old organelles, viruses, bacteria
Not found in plant cells or prokaryotes
Role of lysosomes in development?

45. Mitochondria Function: powerhouse of the cell; produces energy!
Structure: 2 membranes, have their own DNA
Question: In what types of cells would mitochondria be the most numerous?

47. Chloroplasts
Function: the organelles in a plant cell in which the energy of sunlight is converted into chemical energy (photosynthesis)
Structure: 2 membranes, contains DNA, chlorophyll (green color!)

49. Vacuole Found in plants and animals
Large central vacuole in plant cells
Function: fluid-filled organelle that stores enzymes and wastes

51. Cell Wall Not found on animal cells; on plant cells and bacteria
Function: supports and protects the cell
Structure: cellulose, pores

53. Cytoskeleton
Function: a structure to maintain the shape and size of cells (like our skeletons!)
Structure: a network of long protein strands located in the cytosol; 2 types
1) Microfilaments (thinner)
2) Microtubules (thicker)

55. Cilia / Flagella
Structure/Function: hair-like organelles that extend from the surface of the cell, where they assist in movement
Made of microtubules!
Differences between cilia and flagella