1. Basic Unit of All Living Things
Cells:
Basic Unit of All Living Things 1 3 2

2. Effect of Size on the Surface Area to Volume Ratio
As the size of a cell increases, its volume increases by the cube of the side, whereas the surface area only increases by the square of the side.
Therefore, as the cell size increases the surface area to volume ratio decreases.
There is less surface area per unit of volume in a larger cube.
(More total surface area total but increase in surface area is less than increase in volume)

4. Importance of Surface Area
Many substances have to be transported in or out of the cell.
For example, food molecules and oxygen have to be transported into the cell. Waste materials such as carbon dioxide have to be removed from the cell.
The cell needs to have an adequate amount of surface area per unit of volume to support the needs of the cell.

5. Cell Theory All organisms are composed of one or more cells.
The cell is the basic unit of organization in all organisms.
All cells come from preexisting cells.

6. 2 Basic Cell Types Prokaryotic cells-
Cells lack membrane-bound organelles (organelles= is a part of a cell that is specialized to perform a specific function).
DNA is not separated from the rest of the cell.
Bacteria are made of prokaryotic cells.
Maximum size is of bacteria cells is about 0.001mm
(= 1 micrometer which is abbreviated µm)

7. Cell Types Cont.
Eukaryotic Cell:
Cell that contains membrane-bound organelles, including a nucleus.
Internal organization (specialized organelles) improves the efficiency of the cell.
Maximum size is x larger than prokaryotes, up to 0.1 mm (100 µ m)
Examples:
Plants
Animals
Fungi
Protists (unicellular eukaryotes)

8. Thin, flexible layer that surrounds all cells.
Parts of a Cell
Plasma (Cell) membrane:
Thin, flexible layer that surrounds all cells.
Controls what can enter/exit the cell.

9. Cytoskeleton: A network of proteins inside the cell that provide structure and support. Constantly changes to meet the needs of the cell. (Cyto = cell)
Cytoplasm= The gel-like substances that fills the cell. It contains enzymes, other organic molecules, organelles, water…

10. Cell wall:
Rigid layer outside of plasma membrane found in some cells.
Provides support.
Plants have cell walls made of cellulose.

11. Nucleus: The “control center” of the cell
Nucleus: The “control center” of the cell. Contains the DNA, which encodes the information to build proteins. Ribosomes: Site of protein synthesis. Ribosomes are present in both prokaryotic and eukaryotic cells (not a membrane-bound organelle).

12. Chloroplast:
Site of photosynthesis.
Contains a green pigment called chlorophyll.
Chloroplasts are found only in plant cells and some photosynthetic protists.

13. Mitochondria:
The “powerhouse” of the cell.
Site of cellular respiration, the process in which sugars (and other food molecules) are broken down into carbon dioxide and water.
The energy that is released is used to produce ATP which is the “energy currency” of the cell.
Mitochondria are present in all eukaryotic cells.

14. Structure of Mitochondria
Fold inner membrane creates greater surface area for the many enzymes involved in cellular respiration.

15. Endoplasmic reticulum (ER):
A network of folded membranes in the cell.
Smooth ER:
Site of lipid synthesis.
Rough ER:
ER that is studded with ribosomes.
Proteins produced by the ribosomes
are folded and transported.

16. Golgi apparatus: Flattened membrane sacs where proteins transported from the rough ER are chemically modified, and repackaged for their final destination.

17. Vesicles:
Small membrane-bound sacs that separate substances from the rest of the cell and also for transporting substances.
Vesicles are short-lived and are formed and recycled as needed.
Vacuole:
Storage compartment in the cell.
Many plants cells have a large central vacuole that store fluids and help provide support when filled with water.

18. Lysosome:
Digestive compartment that contains enzymes that break-down worn-out cell parts and foreign material (such as viruses).
The enzymes in the lysosomes must be separated from the rest of the cell.

19. Organelles for Cell Movement
Cilia: Short, numerous hair-like projections, that move the cell or move fluid over the cell surface. Example: Paramecium Flagellum (plural- flagella): Longer projection that move in a whip-like motion. Often a single tail or present in fewer numbers than cilia. Example: Sperm

20. Click image to start

21. Relative Sizes of Cells, Organelles, Viruses, Molecules and Atoms:

22. Unicellular: An organism made of only one cell
Unicellular: An organism made of only one cell. Example: Diatom Multicellular: An organisms made of many cells. The average human has approximately 100 trillion cells.

23. Levels of Organization
Tissue: A group of similar cells that work together. Example: Muscle tissue Organ: A group of different types of cells that work together for a specific function. Example: The heart Organ System: A group of organs that work together. Example: The circulatory system

24. Applying the Concepts
Some cells have a large number of mitochondria. What type of cell might it be and why? A cell with high energy needs since mitochondria provide usable energy for the cell. Example: Muscle cells

25. Applying the Concepts
Name 3 differences between plant cells and animal cells. Plant cells have cell walls, and typically have chloroplasts and a large central vacuole.