Eukaryotic Cell Composition
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Explore the structure and function of eukaryotic cells, including the nucleus, organelles, and cytoskeleton. Learn about the roles of key components such as mitochondria, lysosomes, and endoplasmic reticulum.
Eukaryotic Cell Composition
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Presentation Transcript
7.2 Eukaryotic Cell Structure • Objectives: • Describe the function of the nucleus • Describe the functions of the major cell organelles • Identify the main roles of the cytoskeleton
7.2 Eukaryotic Cell Structure • Cell organization • Organelles • “little organs” • the specialized structures within the cell that perform a function
Cytoplasm • Description • The fluid that fills the entire cell • The portion of the cell outside of the nucleus • Function • Makes up about 70% of the cells volume. • Most of the cells chemical reactions occur here
The Nucleus • Function • “Control center” of the cell • Contains nearly all of the cell’s DNA (the coded instructions for making proteins & other important molecules)
Nuclear Envelope • Description • Envelope or layer around nucleus • Made of 2 membranes • Function: • Allows for materials (like RNA, proteins, & other molecules) to come in and out through pores
Inside the Nucleus • Chromatin • Description: • Looks like granular material • Usually spread throughout the nucleus • Function: • During cell division, it condenses to form chromosomes • Made of DNA bound to protein • Chromosomes • Description: Threadlike structures, often in X shape • Function: Contain genetic information
Inside the Nucleus Chromosome
Inside the Nucleus • Nucleolus • Description: Small, dense area in nucleus • Function: Directs the formation of ribosomes
Ribosomes • Description: • Small dots • Found throughout cytoplasm • Pieces of RNA & protein • Function: • Proteins are assembled on these • Build proteins based on instructions from DNA
Endoplasmic reticulum – “ER” • Description • folded membranes • Surrounds nucleus • Function • Makes lipids for the cell membrane • Makes proteins & other materials that are exported from the cell • Two types- rough and smooth
Rough ER • Description: Has ribosomes on its surface • Function: • Modifies proteins • Produces proteins that will eventually be secreted out of the cell
Smooth ER • No ribosomes • Has enzymes that carry out certain tasks, like making membrane lipids & the detoxification of drugs • Liver cells usually contain large amounts of smooth ER
Golgi Apparatus • Description: • Stack of flat discs • NOT surrounding nucleus • Function: • Modifies, sorts, & packages proteins & other materials from the ER for storage in the cell or release outside the cell
Lysosomes • Description: • Small balls or membrane ‘pockets’ • Function: • The “clean-up crew” • Filled with enzymes that break down • Lipids • Carbohydrates • Proteins • Cellular debris
Lysosomes (cont) • Have been linked to diseases, such as Tay Sach’s • Tay Sach’s is a disorder that is caused by a genetic defect that prevents the formation of an essential enzyme that breaks down lipids • These lipids build up in the body and can cause nerve damage; prognosis is not good
Peroxisome • Description: • Looks like lysosomes – small balls or membrane ‘pockets’ • Function: • Contains enzymes such as catalase • Hydrogen peroxide is broken down here
Vacuoles • Description: • Large sac-like, membrane enclosed structures • Function: • Store water, salts, proteins, & carbohydrates • Pressure allows plants to support heavy structures
Mitochondria • Description: • Oval with folded membrane inside • Function: • “Powerplant” of the cell • Changes the chemical energy stored in food into compounds that are more convenient for the cell to use (ATP)
Chloroplast • Description • 2 membranes surround the organelle • Stacks of membranes inside- grana • Green
Chloroplasts • Function: • Capture energy from the sun & convert it into chemical energy – photosynthesis! • Contains chlorophyll- green pigment
Cytoskeleton • Description: • a framework of filaments throughout the cell • Function: • Helps cells keep its shape • Helps the cell move • Made up of microfilaments and microtubules
Microfilaments • Description: • Branching threadlike structures • Function: • Help cell maintain shape & allow it to move • Assembly and disassembly cause amoeboid movement • Made up of a protein called actin
Microtubules • Description: • Hollow tubes in cytoskeleton • made up of proteins known as tubulins • Function: • Help cells maintain shape • Helps separate chromosomes in cell division • Builds projections from the cell surface - cilia & flagella
Centrioles • Description: • Located near the nucleus • A pair of short cylinders • Function: • Help organize cell division • Only in animal cells