1. Cell Overview Cells are the basic unit of life.
Cells are classified as prokaryotes or eukaryotes
Cells
Prokaryote
Eukaryote

2. Prokaryotes Oldest cells – probably the first life on earth
Very simple cells composed of 2 main parts
Cell Membrane – the outer boundary of the cell
Cytoplasm – jelly-like interior of the cell
The name prokaryote comes from the Greek pros meaning “before” and karyon meaning “nut”, referring to the nucleus
Most prokaryotes are single celled organisms
Example: bacteria

3. Eukaryote More advanced cells Found in plants and animals
Eukaryotic cells are composed of 4 main parts:
Cell Membrane – the outer boundary of the cell
Cytoplasm – jelly-like interior of the cell
Nucleus – the control center of the cell which contains the cell’s genetic material (DNA)
Organelles – structures that carry out cell functions
Organisms can be single-celled or multicellular

4. Eukaryotes Plant cell Animal cell Examples: Single Celled – algae
Multicellular - onion
Examples:
Single Celled: Amoeba, Protozoan
Multicellular: Human

5. Eukaryotes Organelles – membrane-bound compartments within a cell
Allow different internal environments within a single cell
Allow many different chemical reactions to take place without disturbing each other
Allow specialized functions
Almost all Eukaryotic cells have the same basic set of organelles
Some organelles are only found in plant cells, others are only found in animal cells

6. Cell (plasma) membrane
Defines the boundary of the cell
Regulates what comes in and goes out (selectively permeable)
Composed of proteins and special lipids called phospholipids
Outer side is hydrophilic
Inner side is hydrophobic
Molecules are fluid-like, not locked in place

7. Cytoplasm
The entire region of the cell between the nucleus and the plasma membrane
Consists of various organelles suspended in fluid
Cytoskeleton is a network of fibers throughout the cytoplasm that give the cells shape

8. Nucleus Houses the cell’s DNA that directs all cellular activity
DNA is attached to proteins in long fibers called chromatin
Enclosed by a membrane (nuclear membrane)
Contains nucleolus
Nucleolus makes ribosomes

9. Chromatin & Chromosomes
Most of the time, the DNA
exists as a mass of very long,
thin fibers called chromatin
The instructions in the
chromatin can be “read” so
that the cell can produce proteins.
When the cell is getting ready to divide, the chromatin condenses into compact chromosomes.
Chromosomes are easier to move, but the instructions can’t be “read” to make proteins.

10. Ribosomes Ribosomes onstruct proteins
Use instructions in the DNA to build proteins
Ribosomes are found on the Endoplasmic Reticulum
Make proteins for membranes and export outside the cell
Ribosomes are also found suspended in the cytoplasm
Make enzymes and proteins for use inside the cell

11. Endoplasmic Reticulum
A network of membranes in the cytoplasm.
Two types: rough ER and smooth ER
Synthesize proteins (rough ER)
Proteins can be secreted by the cell, or packaged and sent out of the cell to other cells
Synthesize lipids (smooth ER)
Example: hormones

12. Golgi Bodies
Takes products from the ER and modifies, stores, and routes to next destination
Enzymes in the golgi bodies refine and modify the ER products
Example: fold proteins into their final shape

13. Lysosomes
Contain digestive enzymes that can break down macromolecules such as proteins, nucleic acids, and polysaccarides
Digest food to nourish the cell
Help destroy harmful bacteria
Recycle damaged organelles to make molecules available for construction of new ones.

14. Chloroplasts Photosynthetic organelles found in some plants and algae
Convert light energy from the sun to the chemical energy stored in sugars and other organic compounds

15. Mitochondria Powerhouse of the cell Site of cellular respiration
Releases energy from sugars and other organic molecules into an energy source the cell can use
The energy that a cell uses is called ATP. We will learn about it in the next chapter.

16. Vacuoles Large membrane- bound sacs
Store undigested nutrients or chemicals
Many plants have a large central vacuole
Vacuoles in flower petals may contain pigments

17. Cell Wall Protects the plant cell and maintains its shape
Located outside the plasma membrane
only plant cells and prokaryotes have cell walls
Animal cells do not
Made of cellulose

18. Cytoskeleton A network of fibers extending throughout the cytoplasm
Microtubules – straight tubes of protein that give rigidity and shape to the cell.
Organelles can move along microtubules
Microfilaments – thin solid rods of protein that slide past each other to enable the cell to change shape
Looks like an oozing movement (ex. Amoeba or white blood cells)

19. Centrioles Pair of tubular structures
Important in cell division of animal cells and protists

20. Cilia & Flagella
Flagella are long, thin, whip-like structures that enable some cells to move
Wave in an S-shaped motion that propels the cell
Cilia are short, hair-like structures that surround a cell
Have a back and forth motion that moves the cell
Can also be found on stationary cells in a multicellular organism
Example: the cells lining your windpipe have cilia that move mucus out of your lungs

21. Multicellular Organisms
Each organelle performs basically the same functions in all cell types
Organelles vary in amount and properties by cell type.
Allows cells to perform specialized functions
All cells carry on the basic activities of life
In a multicellular organism, each cell type also takes on specialized functions
A group of cells with the same specialization works together to perform a function
Tissues, organs, systems

22. R&C #1 p. 277
Explain why it is important for all cells to have a cell membrane. Why might it be beneficial?

23. #2 a. Prokaryotes Vs. Eukaryotes

24. #2 b. Plant Cells vs. Animal Cells

25. R&C #4 p. 277
What differences are likely to exist between single- celled organisms and the cell of a multicellular organism?

26. R&C #5 p. 277
Build a concept map using the following words: atoms, carbohydrates, cells, elements, lipids, nucleic acids, organic molecules, and organism.