Chapter 2: Cells Aim: How are all cells alike?

Cell Traits Have an outer covering called a cell membrane Cytoplasm-contains hereditary material that controls life of cell Cell come in many sizes and shapes Two groups: 1.Prokaryotic: no membrane-bound structures 2.Eukaryotic: membrane-bound structures

Aim: What are the functions of each part of a cell?

1. Cell Wall Found in plants, algae, fungi, and most bacteria Tough, rigid outer covering Protects the cell Gives it shape Made up of cellulose Lignin-makes cell wall rigid

2. Cell Membrane Protective layer around all cells Regulates interactions between the cell and environment Water moves freely through it Food particles enter through it Wastes leave through it

3. Cytoplasm Gelatin-like substance Constantly flowing inside cell membrane Important chemical reactions occur in it Cytoskeleton-enables cells to move Life processes occur here Eukaryotic cells have organelles in cytoplasm

4. Nucleus Directs all cell activities Separated from cytoplasm by a membrane Contains DNA Nucleolus

5. Chloroplast Only in plants Food is made here Contains chlorophyll Chlorophyll uses the Sun’s energy to make glucose (sugar)

6. Mitochondrion Stores energy from food Releases energy by breaking down foods into CO 2 & H 2 O Active cells have more mitochondrion ◦ Example: muscle cells

7. Ribosomes Makes protein for the cell Not-membrane bound Some float in cytoplasm Some attached to endoplasmic reticulum Made in the nucleolus Receive directions from hereditary material on when and how to make proteins

8. Endoplasmic Reticulum(ER) Extends from the nucleus to the cell membrane Series of folded membranes Materials are processed and moved around in the cell Takes up a lot of space Smooth ER-no ribosomes attached Rough ER-ribosomes attached

9. Golgi Bodies Stacked flatten membranes Sort proteins and other substances and package them into vesicles Vesicles deliver these substances to areas inside the cell Also carry substances to the cell membrane that need to be released

10. Vacuole Temporary storage for materials Stores water, waste products, food and other materials Plant cells-vacuole very large 11. Lysosomes Contain digestive chemicals that break down food molecules, cell wastes, and worn out cell parts Membrane keeps chemicals from leaking into cytoplasm and destroying the cell

Aim: What is the difference between tissue, organs and organ systems?

Aim: What is the Cell Theory?

Cell Theory Summarizes conclusions made by Rudolf Virchow and other scientists 1. All organisms are made up of one or more cells 2. The cell is the basic unit of organization in organisms 3. All cells come from cells-cell division

Aim: How do viruses multiply?

Viruses Nonliving particles No nucleus or other organelles Lack cell membrane Discovered with electron microscope Variety of shapes Can only make copies of itself Examples: ◦ Cold sores ◦ AIDS ◦ Colds ◦ Flu

Multiplying of Viruses Need a host cell Acts in 2 Ways: 1. Active Viruses: ◦ Causes host cell to make new viruses ◦ Figure Latent Viruses ◦ Virus enters the cell and its hereditary material becomes part of the cell’s hereditary material ◦ As the host cell reproduces so does the virus

Virus can be latent for many years Environmental factors can activate the virus ◦ Example: cold sores

Viruses affect on Organisms Attack animals, plants, fungi, protists and all prokaryotes Some viruses only infect specific cells ◦ Ex: potato leafroll virus Some affect a range of hosts ◦ ex: rabies Attaches to the host cell by the wind or inhaled by an animal Virus and attachment site of host cell must match exactly Bacteriophages-viruses that infect bacteria ◦ Differ from other viruses-enter and release DNA differently

Aim: Why are vaccines important?

Vaccines Used to prevent diseases Made from weakened virus particles that can cause disease Made for measles, mumps, smallpox, chicken pox, polio and rabies Edward Jenner developed first vaccine in 1796-smallpox Antibiotics treat only bacterial infections Viral infections can be fought by making interferons

Public health measures for preventing viral diseases: ◦ Vaccinating people ◦ Improving sanitary conditions ◦ Quarantining patients ◦ Controlling animals that spread disease Through research scientists are discovering helpful uses of some viruses