3.1 Cell Theory. KEY CONCEPT Cells are the Basic unit of life.

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1 3.1 Cell Theory KEY CONCEPT Cells are the Basic unit of life.

2 3.1 Cell Theory The cell theory grew out of the work of many scientists and improvements in the microscope. Many scientists contributed to the cell theory.

3 3.1 Cell Theory Early studies led to the development of the cell theory. The Cell theory has three principles. All organisms are made of cells.

4 3.1 Cell Theory 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.

5 3.1 Cell Theory 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.

6 3.1 Cell Theory 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. cell membrane cytoplasm Bacterium (colored SEM; magnification 8800x)

7 3.1 Cell Theory There are two cell types: eukaryotic cells and prokaryotic cells. Eukaryotic cells have a nucleus. Prokaryotic cells do not have membranebound organelles. nucleus organelles cell membrane

8 3.1 Cell Theory 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. nucleus organelles cell membrane cytoplasm

9 3.2 Cell Organelles KEY CONCEPT Eukaryotic cells share many similarities.

10 3.2 Cell Organelles 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

11 3.2 Cell Organelles Several organelles are involved in making and processing proteins. The nucleus stores genetic information.

12 3.2 Cell Organelles 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

13 3.2 Cell Organelles Several organelles are involved in making and processing proteins. (continued) Ribosomes link amino acids to form proteins.

14 3.2 Cell Organelles 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.

15 3.2 Cell Organelles Other organelles have various functions. Mitochondria supply energy to the cell.

16 3.2 Cell Organelles Other organelles have various functions. Mitochondria supply energy to the cell. Vacuoles are fluid-filled sacs that hold materials.

17 3.2 Cell Organelles 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.

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

18 3.2 Cell Organelles 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.

19 3.2 Cell Organelles Plant cells have cell walls and chloroplasts. A cell wall provides rigid support.

20 3.2 Cell Organelles Plant cells have cell walls and chloroplasts. A cell wall provides rigid support. Chloroplasts convert solar energy to chemical energy.

21 3.3 Cell Membrane KEY CONCEPT The cell membrane is a barrier that separates a cell from the external environment.

22 3.3 Cell Membrane 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. cell membrane carbohydrate chain protein cholesterol protein protein channel

23 3.3 Cell Membrane Cell membranes are composed of two phospholipid layers. The cell membrane is selectively permeable. Some molecules can cross the membrane while others cannot.

24 3.3 Cell Membrane 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

25 3.4 Diffusion and Osmosis KEY CONCEPT Materials move across membranes because of concentration differences.

26 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

27 3.4 Diffusion and Osmosis Diffusion and osmosis are types of passive transport. Molecules diffuse down a concentration gradient.

28 3.4 Diffusion and Osmosis Diffusion and osmosis are types of passive transport. Osmosis is the diffusion of water molecules across a semipermeable membrane.

29 3.4 Diffusion and Osmosis Diffusion and osmosis are types of passive transport. There are three types of solutions. isotonic hypertonic hypotonic

30 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.

31 3.5 Active Transport, Endocytosis, and Exocytosis KEY CONCEPT Cells use energy to transport materials that cannot diffuse across a membrane.

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.

32 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.

3.5 Active Transport, Endocytosis, and Exocytosis A cell

of material in vesicles during the processes of

Cells use energy to transport material in vesicles.

33 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.

large amounts of material in vesicles during the

34 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.

3.2 Cell Organelles. KEY CONCEPT Eukaryotic cells share many similarities.

3.2 Cell Organelles. KEY CONCEPT Eukaryotic cells share many similarities. KEY CONCEPT Eukaryotic cells share many similarities. ! Cells have an internal structure. ! Cells have an internal structure. The cytoskeleton has many functions. ! Cells have an internal structure. The