Topic 3: The Incredible Cell

What is a cell? Very smallest unit of living matter Are building blocks Cells work together to build more complicated organisms

Cell theory 1. Cell is the basic unit of life 2. All living organisms are composed of cells 3. Cells come from pre-existing cells 4. Heredity information is passed on from cell to cell 5. All cells have the same basic chemical composition 6. Energy flow occurs within cells

A Cell’s Internal Structures Organelles Internal structures that perform specific functions 8 common organelles to ALL cells

1. Cell membrane Thin layer that surrounds the cell Keeps all of the other organelles inside Gateway Allows required materials in and wastes out Selectively permeable Only some materials move in and out

2. Cytoplasm Medium (substance) that holds the organelles in place Contains water, minerals, vitamins, salts, and other chemicals ‘Kitchen’ of the cell Where all of the reactions happen

3. Nucleus Command center of the cell Directs all activities that occur within the cell Contains DNA Serves as a blueprint

4. Mitochondria Powerhouse of the cell Produces energy Site where sugar is converted into a usable form called ATP

5. Vacuole Storage room for nutrients, water and other materials

6. Endoplasmic reticulum (ER) Network of folded membranes 2 jobs: Produces proteins, lipids (fats), steroids Acts as an assembly and packaging system

7. Golgi apparatus Network of folded membranes & bubble-like vesicles Packaging and transport system

8. Lysosomes 2 jobs: Digestion machines Garbage disposal Contains enzymes that digest (break down) materials

Type specific organelles Animal cells Have the 8 organelles common to all cells Vacuoles are small Generally circular in shape

Plant cells Vacuoles are large If little water is stored, plant is limp If lots of water is stored, plant is rigid

Have the 8 organelles common to all cells + 2 additional organelles 9. Cell wall Frame of the cell (outside the membrane) Provides strength and support 10. Chloroplast “Solar panel” of the cells Collects sunlight Where photosynthesis occurs Contain chlorophyll (green pigment)

Movement of Substances in Cells

All cells need to take in materials & get rid of wastes It is the cell membrane that allows this happen Tiny openings that allow SOME particles (eg. oxygen, water) are allowed to pass through Cell membrane = selectively permeable

Diffusion Movement of particles from an area of high concentration to an area of low concentration Continues until the concentration of particles is the same everywhere

Osmosis Diffusion of water The amount of water inside the cell must stay approximately the same as the amount outside Why?

Cells & Organisms Unicellular Made of only a single cell Amoeba Paramecium http://www.youtube.com/watch?v=pvOz4V699gk

Advantages of being unicellular? Disadvantages of being unicellular?

Multicellular Made of 2 or more cells Cells are specialized Each cell type performs a specific job Cells within the organism interact with one another

Advantages of being multicellular? Disadvantages of being multicellular?