Endocytosis and Exocytosis PDF

# Objectives * **SWBAT** describe active transport. * **SWBAT** distinguish among endocytosis, exocytosis, and phagocytosis. ## Main Ideas * Proteins can transport materials against a concentration gradient. * Endocytosis and exocytosis transport materials across the cell membrane in vesicles. #...

# Objectives * **SWBAT** describe active transport. * **SWBAT** distinguish among endocytosis, exocytosis, and phagocytosis. ## Main Ideas * Proteins can transport materials against a concentration gradient. * Endocytosis and exocytosis transport materials across the cell membrane in vesicles. # Vocabulary Section 3.5 * Endocytosis (endocitosis) * Exocytosis (exocitosis) * Phagocytosis (fagocitosis) * Active transport (transporte activo) * ATP (adenosine triphosphate) # Endocytosis * "Inside" (going inside the cell) # Exocytosis * "Outside" (going outside the cell) # Endocytosis * Is a type of active transport that moves particles, such as large molecules, parts of cells, and even whole cells, into a cell. # Endocytosis can be further subdivided into the following categories: * Phagocytosis * Pinocytosis * Receptor-mediated endocytosis # Phagocytosis * Is the process by which large particles, such as cells or relatively large particles, are taken in by a cell. * Literally: "Cell eating" # Pinocytosis * Is a form of endocytosis in which a cell takes in small amounts of extracellular fluid. * Literally: "Cell drinking" # Receptor-mediated endocytosis * Is a form of endocytosis in which receptor proteins on the cell surface are used to capture a specific target molecule. The receptors, which are transmembrane proteins, cluster in regions of the plasma membrane known as coated pits. # Exocytosis * Is a form of bulk transport in which materials are transported from the inside to the outside of the cell in membrane-bound vesicles that fuse with the plasma membrane. # Two Types of Transport * There are two ways of transporting materials across a cell membrane. They are: * **Passive Transport** - We have already looked at this. * **Active Transport** - Actively drives molecules across the cell membrane from a region of lower concentration to a region of higher concentration. Requires energy input. # Passive transport * Diffusion * Facilitated diffusion # Active Transport * ATP # Active Transport * Energy # ATP (Adenosine Triphosphate) * Passive transport * Active transport * Diffusion * Facilitated diffusion # Chemiosmosis A diagram shows the steps of chemiosmosis: * **Intermembrane space:** contains H+ ions which are pumped across the inner mitochondrial membrane * **Inner mitochondrial membrane:** * **ADP + Pi** * **ATP synthase** * **H+ ** * **ATP** (ATP is created via diffusion through protein channel) * **Mitochondrial matrix:** contains the **proton pump** # Endocytosis * Endocytosis - the process of taking liquids or fairly large molecules into a cell by engulfing them in a membrane. * The cell membrane makes a pocket around the substance. # Endocytosis A diagram shows how receptor-mediated endocytosis works: * **Receptor-mediated endocytosis** * **Receptor** * **Coat protein** * **Coated vesicle** * **Coated pit** * **Specific molecule** * **Plasma membrane** * **Coated pit** * **Material bound to receptor proteins** # Endocytosis A diagram shows how lysosomes work: * **Lysosomal enzymes** break down the vesicle membrane and the vesicle's contents are release into the cell. # Phagocytosis * They are your body's enforcers. # Exocytosis A diagram shows how exocytosis works: * **ER** (includes transmembrane glycoproteins) * **Secretory protein** * **Glycolipid** * **Golgi apparatus** * **Vesicle** * **Plasma membrane**: * **Cytoplasmic face** * **Extracellular face** * **Secreted protein** * **Transmembrane glycoprotein** * **Membrane glycolipid** # Exocytosis in Neuron A diagram shows a neuron releasing neurotransmitters into the synapse: * **Axon** * **Neurotransmitter released into synapse** * **Neurotransmitter attached to receptor** * **Dendrite** * **Neurotransmitter stored in vesicles** * **Enzyme that destroys neurotransmitter** # Exocytosis - Neuron to Muscle A diagram shows a neuron releasing acetylcholine into the synapse: * **Neuron** * **Endocytosis ** * **Synaptic vesicles** * **Exocytosis active zone** * **Acetylcholine receptors** * **Muscle** * **Acetylcholine** * **Neuropeptide modulators** # Questions * How do endocytosis and exocytosis differ from one another? * List one function that exocytosis carries out in the human body? * List one function that endocytosis carries out? * What might happen if vesicles in your neurons were suddenly unable to fuse with the cell membrane? * How do endocytosis and exocytosis differ from diffusion?