1. Basic Structure of a Cell
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2. CELL THEORY All living things are made of cells
Cells are the basic unit of structure and function in an organism (basic unit of life)
Cells come from the reproduction of existing cells (cell division)

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Number of Cells
Organisms may be:
Unicellular – composed of one cell
Multicellular- composed of many cells that may organize into tissues, etc.
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4. Typical cells range from 5 – 50 micrometers (microns) in diameter
CELL SIZE
Typical cells range from 5 – 50 micrometers (microns) in diameter

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How Big is a Micron ( µ ) ?
1 cm = 10,000 microns 1” = 25,000 microns
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6. Factors Affecting Cell Size
Surface area = L x W
Volume of a cell = L x W x H
Therefore, Volume increases FASTER than the surface area
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Cell Size
When the surface area is no longer great enough to get rid of all the wastes and to get in enough food and water, then the cell must divide
Therefore, the cells of an organism are close in size
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Cell Size
Question: Are the cells in an elephant bigger, smaller, or about the same size as those in a mouse?
About the same size, but …
The elephant has MANY MORE cells than a mouse!
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9. Multicellular Organisms
Cells in multicellular organisms often specialize (take on different shapes & functions)
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Cell Specialization
Cells in a multi-cellular organism become specialized by turning different genes on and off
This is known as DIFFERENTIATION
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11. Specialized Animal Cells
Muscle cells
Red blood cells
Cheek cells

12. Specialized Plant cells
Guard Cells
Pollen
Xylem cells
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Types of Cells
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14. Prokaryotes – The first Cells
Cells that lack a nucleus or membrane-bound organelles
Simplest type of cell
Single, circular chromosome
Includes bacteria
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Prokaryotes
Nucleoid region (center) contains the DNA
Surrounded by cell membrane & cell wall (peptidoglycan)
Contain ribosomes (no membrane) in their cytoplasm to make proteins
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Eukaryotes
Cells that HAVE a nucleus and membrane-bound organelles
More complex type of cells
Includes protists, fungi, plants, and animals
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Eukaryotic Cell
Contain 3 basic cell structures:
Nucleus
Cell Membrane
Cytoplasm with organelles
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Organelles
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Organelles
Very small (Microscopic)
Perform various functions for a cell
Found in the cytoplasm
May or may not be membrane-bound
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20. Animal Cell Organelles
Ribosome (attached)
Nucleolus
Ribosome (free)
Nucleus
Cell Membrane
Nuclear envelope
Mitochondrion
Smooth
endoplasmic
reticulum
Rough
endoplasmic
reticulum
Centrioles
Golgi apparatus
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Plant Cell Organelles
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1. Plasma Membrane
Composed of a constantly moving, double layer
Surrounds outside of ALL cells
Controls what enters or leaves the cell
We will discuss membranes a LOT after break
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains
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2. Cell Wall
Supports and protects cell
Found outside of the cell membrane
In most prokaryotes, plants, and fungi
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24. 3. Cytoplasm of a Cell Jelly-like substance enclosed by cell membrane
Provides a medium for chemical reactions to take place
Contains organelles to carry out specific jobs
Found in ALL cells

25. 4. The Control Organelle - Nucleus
Controls the normal activities of the cell
Contains the DNA in chromosomes
Bounded by a nuclear envelope (membrane) with pores
Usually the largest organelle
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26. Inside the Nucleus - The genetic material (DNA) is found here
DNA is condensed & wrapped around proteins forming
as CHROMOSOMES in dividing cells
DNA is spread out
And appears as CHROMATIN in non-dividing cells
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What Does DNA do?
DNA is the hereditary material of the cell
Genes that make up the DNA molecule code for different proteins
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5. Ribosomes
Made of PROTEINS and rRNA
“Protein factories” for cell 
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29. Be free (unattached) in the cytoplasm
Ribosomes
Can be attached OR
Be free (unattached) in the cytoplasm
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30. 6. Mitochondrion (plural = mitochondria)
“Powerhouse” of the cell
Site of CELLULAR RESPIRATION (burning glucose) that generates cellular energy (ATP)
More active cells like muscle cells have MORE mitochondria
All eukaryotic cells have mitochondria
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MITOCHONDRIA
Made of a DOUBLE membrane
Inner membrane is highly folded to increase surface area
Has its own DNA
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Interesting Fact ---
Mitochondria Come from cytoplasm in the EGG cell during fertilization
Therefore …
You inherit your mitochondria from your mother!
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7. Chloroplasts
Found only in producers (organisms containing chlorophyll)
Contains enzymes & pigments for Photosynthesis
Never in animal cells
Bacteria can be photosynthetic, but do not have chloroplasts
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Chloroplasts
Made of a DOUBLE membrane
Inner membrane highly folded to increase surface area
Contains its own DNA
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8. Cytoskeleton
Helps cell maintain cell shape
Also help move organelles around within the cell
Helps move the cell in environment
Made of proteins
Several sizes, like pipes, and
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Cytoskeleton
MICROTUBULES
MICROFILAMENTS
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Endomembrane System
Includes nuclear membrane connected to ER connected to cell membrane as well as Golgi apparatus and vesicles
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38. 9. Endoplasmic Reticulum - ER
Network of hollow membrane tubules
Connects to nuclear envelope & cell membrane
Functions in Synthesis of cell products & Transport
Two kinds of ER ---ROUGH & SMOOTH
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39. 9a. Rough Endoplasmic Reticulum (Rough ER)
Has ribosomes on its surface
Makes membrane proteins and proteins for EXPORT out of cell
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40. 9b. Smooth Endoplasmic Reticulum
NO ribosomes on its surface
Is attached to rough ER
Makes cell products that are USED INSIDE the cell, especially membrane pieces for organelles
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41. 10. Golgi Apparatus Stacks of flattened membrane sacs
Receive products from ER on receiving side (cis face)
Vesicles with modified proteins pinch off the ends of shipping side (trans face)
CIS
TRANS
Vesicle

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Golgi Apparatus
Modify, sort, & package
molecules from ER
for storage OR transport out of cell
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11. Vesicles
Membrane sacs designed to transport materials
Pinch or bud off other membranes
At destination, fuse with other membranes
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12. Vacuoles
Fluid filled sacks for storage
Small or absent in animal cells
Plant cells have a large Central Vacuole
No vacuoles in bacterial cells
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12a. Central Vacuoles
In plants, they store Cell Sap
Includes storage of sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes
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12b. Contractile Vacuole
Found in unicellular protists like paramecia
Regulate water intake by pumping out excess
Keeps the cell from lysing (bursting)
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47. 13. Lysosomes Contain digestive enzymes
Fuse with vesicles to break down food, bacteria, and worn out cell parts for cells
Programmed for cell death (AUTOLYSIS)