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

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.

3.1 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. More was learned about cells as microscopes improved.

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. More was learned about cells as microscopes improved. The cell theory is a unifying concept of biology.

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.

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.

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.

3.1 Cell Theory Prokaryotic cells lack a nucleus and most internal structures of eukaryotic cells. All cells share certain characteristics.

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. Bacterium (colored SEM; magnification 8800x)

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. Bacterium (colored SEM; magnification 8800x) cell membrane

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. Bacterium (colored SEM; magnification 8800x) cell membrane cytoplasm

3.1 Cell Theory There are two cell types: eukaryotic cells and prokaryotic cells.

3.1 Cell Theory There are two cell types: eukaryotic cells and prokaryotic cells. Eukaryotic cells have a nucleus. nucleus cell membrane

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

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

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 cell membrane organelles cytoplasm

3.2 Cell Organelles KEY CONCEPT Eukaryotic cells share many similarities.

3.2 Cell Organelles Cells have an internal structure.

3.2 Cell Organelles Cells have an internal structure. The cytoskeleton has many functions.

3.2 Cell Organelles Cells have an internal structure. The cytoskeleton has many functions. – –supports and shapes cell

3.2 Cell Organelles Cells have an internal structure. The cytoskeleton has many functions. – –supports and shapes cell – –helps position and transport organelles

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

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

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

3.2 Cell Organelles Several organelles are involved in making and processing proteins.

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

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.

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.

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

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. – –RER - rough endoplasmic reticulum – –SER - smooth endoplasmic reticulum

3.2 Cell Organelles Several organelles are involved in making and processing proteins. (continued)

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

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.

3.2 Cell Organelles Other organelles have various functions.

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

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

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. Lysosomes contain enzymes to digest material. Centrioles are tubes found in the centrosomes.

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.

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.

3.2 Cell Organelles Plant cells have cell walls and chloroplasts.

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

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

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

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers.

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers. The cell membrane has two major functions. cell membrane

3.3 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 cell membrane outside cell inside cell

3.3 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 cell membrane outside cell inside cell

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers.

3.3 Cell Membrane cell membrane Cell membranes are composed of two phospholipid layers. The cell membrane is made of a phospholipid bilayer.

3.3 Cell Membrane 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. protein cholesterol protein carbohydrate chain protein channel

3.3 Cell Membrane 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. protein cholesterol protein carbohydrate chain protein channel

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers.

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.

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.

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.

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

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

KEY CONCEPT Materials move across membranes because of concentration differences. 3.4 Diffusion and Osmosis 59

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. osmosis diffusion 3.4 Diffusion and Osmosis 60

Diffusion and osmosis are types of passive transport. Molecules diffuse down a concentration gradient. 3.4 Diffusion and Osmosis 61

Diffusion and osmosis are types of passive transport. Osmosis is the diffusion of water molecules across a semipermeable membrane. 3.4 Diffusion and Osmosis 62

Diffusion and osmosis are types of passive transport. There are three types of solutions. isotonic 3.4 Diffusion and Osmosis hypotonic hypertonic 63

Some molecules can only diffuse through transport proteins. Some molecules cannot easily diffuse across the cell membrane. Facilitated diffusion is diffusion through transport proteins. 3.4 Diffusion and Osmosis 64

KEY CONCEPT Cells use energy to transport materials that cannot diffuse across a membrane. 3.5 Active Transport, Endocytosis, and Exocytosis 65

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). 3.5 Active Transport, Endocytosis, and Exocytosis Cells use active transport to maintain homeostasis. Active transport occurs through transport protein pumps. 66

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. 3.5 Active Transport, Endocytosis, and Exocytosis Phagocytosis is a type of endocytosis. 67

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. 3.5 Active Transport, Endocytosis, and Exocytosis 68

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