Chapter 3 Cells : The Basic Units of Life

1. Chapter 3 Cells : The Basic Units of Life

2. 5 Levels of Organization of All Living Things • 1. Cells – the basic unit of life • 2. Tissues – cells working together ( muscles, nerves, blood) • 3. Organs – tissues working together ( heart, kidneys, stomach, skin ) • 4. Organ Systems – Organs working together ( Circulatory, Nervous, Digestive)

3. 5. Organism – organ systems working together; (an entire living thing that carries out all the basic life functions)

4. Cell Theory • 1. All organisms are composed of one or more cells. • 2. The cell is the basic unit of life in all living things. • 3. All cells come from existing cells.

5. Two Types of Cells • 1. Prokaryotic cells – do not have a nucleus or any membrane covered organelles; the circular DNA is bunched up in the cytoplasm ( bacteria ) p. 66 • 2. Eukaryotic cells – have a nucleus and cell organelles (p. 67 )

6. The Cell Organelles

7. Cell Wall • Found only in plants • Allows the plant to maintain its shape • Helps to protect and support the structure of a plant • Is made of cellulose ( long chains of sugar molecules ) p. 69

8. Cell Membrane • Provides protection and support for the cell • Controls movement of materials into and out of the cell ( gate keeper of the cell ) • For an animal cell it forms the outer covering • For plant cells it is located just inside the cell wall • P. 68 - 69

9. Nucleus • Control center of the cell ( the brain ) • Chromosomes are located in the nucleus • Nuclear membrane – covering that protects the nucleus • Nucleolus – the dark area in the nucleus that is made up of protein and RNA • P. 69

10. Cytoplasm • Thick, jelly-like substance between the nucleus and the cell membrane • The cell organelles float around in the cytoplasm • P. 63

11. Endoplasmic Reticulum(ER) • Passageways that lead out from the nuclear membrane to the cell membrane and other parts of the cell • It creates some proteins • Helps keep the correct level of nutrients in the cell • Can be smooth ( no ribosomes attached ) • Can be rough ( ribosomes attached ) • P. 70

12. Ribosomes • Grain-like bodies attached to the endoplasmic reticulum or free floating in the cytoplasm • Protein builders of the cell • P. 70

13. Mitochondria • “Powerhouse” of the cell • Makes the energy known as ATP • The more mitochondria a cell has, the more active the cell is ( muscle cells have a lot ) • The only place where oxygen is combined with food to release energy • P. 71

14. Vacuoles • Water-filled sack floating in the cytoplasm • Storage tank for the cell ( may contain food, oil, waste ) • More important to the survival of a plant cell • Much larger in a plant cell • P. 73

15. Golgi Complex • Combines molecules that are to be sent out of the cell • Creates Lysosomes • P. 72

16. Lysosomes • Contains enzymes that digest food molecules and injured cell parts • Common in animal cells • Not often found in plant cells • P. 74

17. Chloroplast • The organelle of plant cells in which photosynthesis takes place • Contains green pigments called chlorophyll • P. 71 or p. 74

18. Cell Specialization • Each cell performs a specialized function • Occurs only in multicellular organisms

19. Division of Labor • Each part has a specific job to do