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3.5 Active Transport, Endocytosis, and Exocytosis

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

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3.5 Active Transport, Endocytosis, and Exocytosis

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  1. 3.5 Active Transport, Endocytosis, and Exocytosis • KEY CONCEPT Cells use energy (ATP) to transport materials that cannot diffuse across a membrane.

  2. 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. • Synthesize: In what ways are active transport proteins similar to enzymes?

  3. 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 (ATP) to transport material in vesicles. • Endocytosis is the process of taking material into the cell. • Phagocytosis is a type of endocytosis in which the cell membrane engulfs large particles. Sometimes is called “cell eating”. • During endocytosis, the cell membrane folds inward and fuses together surrounding the substance in a pocket . • The vesicle fuses with a lysosome, or a similar vesicle, where enzymes break down the membrane and its contents. • The pocket pinches off inside the cell, forming a vesicle.

  4. 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 (ATP) to transport material in vesicles. • Exocytosis is the process of expelling material from the cell. • The cell forms a vesicle around material that needs to be removed or secreted. • The vesicle membrane fuses with the cell membrane and releases the contents. • The vesicle is transported to the cell membrane.

  5. Examples of Endocytosis and Exocytosis • Endocytosis – plays a role in the human immune system. • White blood cells called macrophages help your body fight infection by engulfing and destroying materials that do not belong in your body like bacteria cells. • Exocytosis/Endocytosis – plays a role in the human nervous system. • Vesicles within nerve cells carry and release chemicals to other cells to transmit nerve impulses that for example, will cause your muscles to contract. • Hypothesize: What might happen if vesicles in your neurons were suddenly unable to fuse with the cell membrane?

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