1. CELLS
Structure

2. Cell Membrane
Surrounds the cell to separate it from its external environment; it gives support and protection to the cell
Composed of a double layer of phospholipids called the lipid bilayer; it also has proteins embedded in it
The membrane acts as a selective barrier by controlling what substances enter and leave the cell

3. Cell Walls Found outside the cell membrane
Function to give support and protection to the cell
Found in plants, algae, fungi, and several prokaryotes

4. Cell Interior
The cell has two major divisions:
Cytoplasm
Nucleus

5. Cytoplasm
A semi-fluid substance in which all of the cell’s organelles are suspended
Located between the nucleus and the cell membrane
Contains the cytoskeleton, a network of microtubules that support the cell and give it shape

6. Nucleus
The control center of the cell and where the cell’s DNA is located; is divided into 3 parts:
Nuclear Membrane: Separates the nucleus from the cytoplasm and contains pores so that substances may enter or leave the nucleus
Nucleolus: structure within the nucleus that is responsible for making rRNA
Nucleoplasm: similar to the cytoplasm, it is a semifluid substance in which the DNA and nucleolus are suspended

7. Organelles Endoplasmic reticulum (ER): Extensive network of membranes
There are 2 types:
Rough ER: contains ribosomes that make proteins destined to leave the cell
Smooth ER: makes lipids, steroids, and is involved in detoxification; important in cells that are responsible for ridding the body of toxic substances (i.e. liver)

8. Organelles (cont.) Ribosomes:
Structures involved in protein synthesis
Found attached to the RER or suspended in the cytoplasm
Mitochondria: take the energy stored in food and transforms it into chemicals the cell can use
Golgi apparatus:
Series of flat membrane-bound sacs
Packages proteins made from the RER and sends them in membrane-bound vesicles to their destination

9. Organelles (cont.) Lysosome:
Membrane-bound organelles filled with enzymes
These enzymes are used to break down lipids, carbohydrates, and proteins for use by the cell
They also break down old organelles that no longer function

10. Organelles (cont.) Vacuole:
Membrane-bound compartment that serves many functions (i.e. absorbs water, stores proteins, stores wastes, etc.)
Plant cells have one large central vacuole
Animal cells contain several small vacuoles

11. Organelles (cont.)
Chloroplasts: plant cells have these organelles that absorb the energy from sunlight and transform it into chemical energy through the process of photosynthesis