1. Cell Features

2. Cell Theory 1. All living things are made of one or more cells.
2. Cells are the basic unit of structure and function in organisms.
3. All cells arise from existing cells.

3. Small cells function more efficiently than large cells
Small cells can exchange substances more rapidly than large cells because small objects have a higher surface area to volume ratio.
Substances don’t need to travel as far to reach the center of a small cell.

4.
Cells must be small as larger cells find it difficult to bring in enough food, and export enough wastes to keep the cell alive.
As cell size increases, the ratio of cell volume to cell surface area decreases. At some point as cells increase in size, there isn't enough cell membrane to adequately supply the cell interior with enough oxygen, water, and food. When this happens, the cell dies.

5. Common features of cells
Cell membrane – encloses the cell, regulates what enters and leaves the cell
Cytoplasm- interior of a cell
Cytoskeleton- system of microscopic fibers
Ribosomes-make proteins
DNA-instructions for making proteins, regulates cellular activities and reproduction

6. Prokaryotes Smallest and simplest
Single-celled organism that lacks a nucleus and other organelles.
Bacteria
Cell wall –provides structure and support
Flagella- long threadlike structures used for movement

7. Eukaryotic Cells Has a nucleus and membrane bound organelles
Organelle- structure that carries out specific activities in the cell.
Cilia and flagella move some cells through their environment.
Cilia-short hairlike structures

8. Eukaryotic Cells Paramecium Plant Cell
Plant Cell
White Blood Cell and Bacteria ( a prokaryote)

9. Cell Membrane Lipid bilayer Selectively permeable

10. Homework
Read Chapter 3 Section
Answer Questions 1-5