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Learn about the various cytoplasmic organelles found in cells and tissues, including mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, cytoskeleton, and cellular projections. Understand their functions and roles in cellular processes.
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Cells and Tissues Chapter 3
Learning Objectives • Structure and Function of the cytoplasmic organelles
Cytoplasmic Organelles • Mitochondria • “Powerhouses” of the cell • Change shape continuously • Carry out reactions where oxygen is used to break down food • Provides ATP for cellular energy
Cytoplasmic Organelles • Ribosomes • Made of protein and RNA • Sites of protein synthesis • Found at two locations • Free in the cytoplasm • As part of the rough endoplasmic reticulum
Cytoplasmic Organelles • Endoplasmic reticulum (ER) • Fluid-filled tubules for carrying substances • Two types of ER • Rough endoplasmic reticulum • Studded with ribosomes • Synthesizes proteins • Smooth endoplasmic reticulum • Functions in lipid metabolism and detoxification of drugs and pesticides
As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern. Ribosome mRNA Rough ER In the cistern, the protein foldsinto its functional shape. Shortsugar chains may be attachedto the protein (forming aglycoprotein). Protein The protein is packaged in atiny membranous sac called atransport vesicle. Transportvesicle buds off The transport vesicle buds fromthe rough ER and travels to theGolgi apparatus for furtherprocessing or goes directly tothe plasma membrane where itscontents are secreted. Protein insidetransport vesicle Rough Endoplasmic Reticulum
Questions • What is the function of the mitochondria? • Where are ribosomes found? • What is the function of ribosomes? • What are the two parts of the ER and how are they functionally different?
Cytoplasmic Organelles • Golgi apparatus • Modifies and packages proteins • Produces different types of packages • Secretory vesicles • Cell membrane components • Lysosomes
Secretion byexocytosis Rough ER Proteins in cisterna Lysosome fuses withingested substances Cisterna Membrane Transportvesicle Golgi vesicle containingdigestive enzymesbecomes a lysosome Pathway 3 Pathway 2 Golgiapparatus Secretory vesicles Pathway 1 Golgi vesicle containingmembrane componentsfuses with the plasmamembrane Proteins Golgi vesicle containingproteins to be secretedbecomes a secretoryvesicle Plasma membrane Extracellular fluid Figure 3.6
Cytoplasmic Organelles • Lysosomes • Contain enzymes that digest worn-out or nonusable materials within the cell
Cytoplasmic Organelles • Peroxisomes • Membranous sacs of oxidase enzymes • Detoxify harmful substances such as alcohol and formaldehyde • Break down free radicals (highly reactive chemicals) • Replicate by pinching in half
Questions • What is the primary function of the Golgi Apparatus? • What are the differences between lysosomes and perioxisomes?
Cytoplasmic Organelles • Cytoskeleton • Network of protein structures that extend throughout the cytoplasm • Provides the cell with an internal framework
Cytoplasmic Organelles • Cytoskeleton • Three different types of elements • Microfilaments (smallest) • Intermediate filaments • Microtubules (largest)
Cytoplasmic Organelles • Centrioles • Rod-shaped bodies made of microtubules • Direct the formation of mitotic spindle during cell division
Cellular Projections • Not found in all cells • Used for movement • Cilia move materials across the cell surface • Located in the respiratory system to move mucus • Flagella propel the cell • The only flagellated cell in the human body is sperm
Questions: • What is the function of the cytoskeleton? • What are the three elements that make up the cytoskeleton? • Which part is the largest? • What is the function of the centrioles? • What is the only human cell with a flagella?