KEY CONCEPT Cells are the Basic unit of life.

1. KEY CONCEPT Cells are the Basic unit of life.

2. The cell theory grew out of the work of many scientists and improvements in the microscope. • Many scientists contributed to the cell theory.

3. The cell theory grew out of the work of many scientists and improvements in the microscope. • Many scientists contributed to the cell theory. • More was learned about cells as microscopes improved. • The cell theory is a unifying concept of biology.

4. Early studies led to the development of the cell theory. • The Cell theory has three principles. • All organisms are made of cells.

5. Early studies led to the development of the cell theory. • The Cell theory has three principles. • All organisms are made of cells. • All existing cells are produced by other living cells.

6. Early studies led to the development of the cell theory. • The Cell theory has three principles. • All organisms are made of cells. • All existing cells are produced by other living cells. • The cell is the most basic unit of life.

7. Prokaryotic cells lack a nucleus and most internal structures of eukaryotic cells. • All cells share certain characteristics.

8. cell membrane cytoplasm Bacterium (colored SEM; magnification 8800x) • Prokaryotic cells lack a nucleus and most internal structures of eukaryotic cells. • All cells share certain characteristics. • Cells tend to be microscopic. • All cells are enclosed by a membrane. • All cells are filled with cytoplasm.

9. nucleus organelles cell membrane cytoplasm • There are two cell types: eukaryotic cells and prokaryotic cells. • Prokaryotic cells do not have a nucleus. • Prokaryotic cells do not have membrane-bound organelles.

10. KEY CONCEPT Eukaryotic cells share many similarities.

11. Cells have an internal structure. • The cytoskeleton has many functions. • supports and shapes cell • helps position and transport organelles • provides strength • assists in cell division • aids in cell movement

12. Several organelles are involved in making and processing proteins. • The nucleus stores genetic information.

13. Several organelles are involved in making and processing proteins. • The nucleus stores genetic information. • Many processes occur in the endoplasmic reticulum.

14. Several organelles are involved in making and processing proteins. • The nucleus stores genetic information. • Many processes occur in the endoplasmic reticulum. • There are two types of endoplasmic reticulum. • rough endoplasmic reticulum • smooth endoplasmic reticulum

15. Several organelles are involved in making and processing proteins. (continued) • Ribosomes link amino acids to form proteins.

16. Several organelles are involved in making and processing proteins. (continued) • Ribosomes link amino acids to form proteins. • Vesicles are membrane-bound sacs that hold materials.

17. Other organelles have various functions. • Mitochondria supply energy to the cell.

18. Other organelles have various functions. • Mitochondria supply energy to the cell. • Vacuoles are fluid-filled sacs that hold materials.

19. Other organelles have various functions. • Mitochondria supply energy to the cell. • Vacuoles are fluid-filled sacs that hold materials. • Lysosomes contain enzymes to digest material.

20. Other organelles have various functions. • Mitochondria supply energy to the cell. • Vacuoles are fluid-filled sacs that hold materials. • Lysosomes contain enzymes to digest material. • Centrioles are tubes found in the centrosomes. • Centrioles help divide DNA. • Centrioles form cilia and flagella.

21. Plant cells have cell walls and chloroplasts. • A cell wall provides rigid support.

22. Plant cells have cell walls and chloroplasts. • A cell wall provides rigid support. • Chloroplasts convert solar energy to chemical energy.

23. KEY CONCEPT The cell membrane is a barrier that separates a cell from the external environment.

24. cell membrane • Cell membranes are composed of two phospholipid layers. • The cell membrane has two major functions. • forms a boundary between inside and outside of the cell • controls passage of materials outside cell inside cell

25. carbohydrate chain protein cell membrane cholesterol protein protein channel • Cell membranes are composed of two phospholipid layers. • The cell membrane is made of a phospholipid bilayer. • There are other molecules embedded in the membrane. • The fluid mosaic model describes the membrane.

26. Cell membranes are composed of two phospholipid layers. • The cell membrane is selectively permeable. Some molecules can cross the membrane while others cannot.

27. Chemical signals are transmitted across the cell membrane. • Receptors bind with ligands and change shape. • There are two types of receptors. • intracellular receptor

28. Chemical signals are transmitted across the cell membrane. • Receptors bind with ligands and change shape. • There are two types of receptors. • intracellular receptor • membrane receptor

29. 3.4 Diffusion and Osmosis KEY CONCEPT Materials move across membranes because of concentration differences.

30. 3.4 Diffusion and Osmosis Passive transport does not require energy input from a cell. • Molecules can move across the cell membrane through passive transport. • There are two types of passive transport. • diffusion • osmosis

31. 3.4 Diffusion and Osmosis Diffusion and osmosis are types of passive transport. • Molecules diffuse down a concentration gradient.

32. 3.4 Diffusion and Osmosis Diffusion and osmosis are types of passive transport. • Osmosis is the diffusion of water molecules across a semipermeable membrane.

33. 3.4 Diffusion and Osmosis Diffusion and osmosis are types of passive transport. • There are three types of solutions. • isotonic • hypertonic • hypotonic

34. 3.4 Diffusion and Osmosis Some molecules can only diffuse through transport proteins. • Some molecules cannot easily diffuse across the cell membrane. • Facilitated diffusion is diffusion through transport proteins.

35. 3.5 Active Transport, Endocytosis, and Exocytosis KEY CONCEPT Cells use energy to transport materials that cannot diffuse across a membrane.

36. 3.5 Active Transport, Endocytosis, and Exocytosis Active transport requires energy input from a cell and enables a cell to move a substance against its concentration gradient. • Passive transport requires no energy from the cell. • Active transport is powered by chemical energy (ATP). • Active transport occurs through transport protein pumps. • Cells use active transport to maintain homeostasis.

37. 3.5 Active Transport, Endocytosis, and Exocytosis A cell can import and export large materials or large amounts of material in vesicles during the processes of endocytosis and exocytosis. • Cells use energy to transport material in vesicles. • Endocytosis is the process of taking material into the cell. • Phagocytosis is a type of endocytosis.

38. 3.5 Active Transport, Endocytosis, and Exocytosis A cell can import and export large materials or large amounts of material in vesicles during the processes of endocytosis and exocytosis. • Cells use energy to transport material in vesicles. • Exocytosis is the process of expelling material from the cell.