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BU BIOL 118 - Tour of the Cell

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Bio 118 1st Edition Lecture 6 Outline of Last Lecture a. Lipids: What is a Lipid?b. The Importance of Cell Membranesc. Three Types of Lipids Found in Cellsd. Fats & Oils (Triglycerides)e. Sterolsf. Phospholipidsg. Phospholipids & Waterh. Phospholipid Bilayersi. Selective Permeability of Lipid Bilayersj. Many Factors Affect Membrane Permeabilityk. Bond Saturation and Membrane PermeabilityOutline of Current Lecture I. Tour of the Cella. All Cells Haveb. Grouping Cellsc. Prokaryotic Cells- Structural Overviewd. Prokaryotic Cells- Genetic Informatione. Prokaryotic Cells- Internal Structuref. Prokaryotic Cells- External Structureg. An Introduction to Eukaryotesh. Eukaryotic Cellsi. Eukaryotes and Prokaryotes Comparedj. The Nucleusk. Rough Endoplasmic Reticuluml. Smooth Endoplasmic Reticulumm. Golgi Apparatusn. Ribosomeso. Peroxisomesp. Lysosomesq. How are materials delivered to lysosomesr. Vacuoless. Mitochondriat. Chloroplastsu. The Cell Wallv. CytoskeletonThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.w. Cell Systems 1: Nuclear Transportx. Cell Systems 2: The Endomembrane Systemy. The Signal Hypothesisz. How are products shipped from the Golgi?aa. Cell Systems 3: The Dynamic Cytoskeletonbb. Three Types of Cytoskeletal ElementsCurrent LectureAll Cells Have- Nucleic acids: store and transmit information- Proteins: perform most of the cell’s functions- Carbohydrates: chemical energy, carbon, support, identity- Plasma Membrane: selectively permeable membrane barrierGrouping Cells- According to morphology, there are two broad groupings of life:o Prokaryotes: lack a membrane-bound nucleus (nucleoid)o Eukaryotes: Have a nucleus- According to phylogeny, or evolutionary history, there are 3 domans:o Bacteriao Archaeao EukaryaProkaryotic Cells- Structural Overview- All prokaryotes lack a membrane bound nucleus- Recent advances in microscopy reveal complexity in prokaryotic structure- Archaeal cell structure is relatively poorly understood- Bacterial cells vary greatly in size & shape, but most bacteria contain several similaritieso Plasma membrane o A single chromosomeo Ribosomes, which synthesizes proteinso Stiff cell wallProkaryotic Cells- Genetic Information- Most prokaryotic species have one supercoiled circular chromosomes found in the nucleoid region of the cello The chromosome contains a long strand of DNA and a few supportive proteinso In addition to the large chromosome, many bacteria contain plasmidso Small, supercoiled, circular DNA moleculeso Plasmids usually contain genes that help the cell adapt to unusual environmental conditionsProkaryotic Cells- Internal Structure- In addition to the nucleoid chromosome and plasmids, other structures are contained within cytoplasm:o All prokaryotic cells contain ribosomes, consisting of RNA molecules and protein, for protein synthesiso Many prokaryotes have internal photosynthetic membraneso Some prokaryotes have membrane-enclosed organelleso The inside of many prokaryotic cells is supported by a cytoskeleton of long, thin protein filamentsProkaryotic Cells- External Structure- Some prokaryotes have tail-like flagella on the cell surface that spin around to move the cell- Most have a cell wallo Bacterial and archaeal cell walls are a tough, fibrous layer that surrounds the plasma membrane- Many species have an additional layer outside the cell wall composed of glycolipidsAn Introduction to Eukaryotes- Eukaryotes range from microscopic algae to 100 meter tall redwood trees- Many eukaryotes are multicellular, others are unicellular- Most eukaryotic cells are larger than most prokaryotic cellsEukaryotic Cells- The relatively large size of the eukaryotic cell makes it difficult for molecules to diffuse across the entire cello This problem is partially solved by breaking up the large cell volume into several smaller membrane-bound organelles- The compartmentalization of eukaryotic cells offer two primary advantages o Separation of incompatible chemical reactionso Increasing the efficiency of chemical reactionsEukaryotes and Prokaryotes Compared- Four key differences between eukaryotic and prokaryotic cells have been identified:o Eukaryotic chromosomes are found inside a membrane-bound compartment called a nucleuso Eukaryotic cells are often much largero Eukaryotic cells contain extensive amounts of internal membraneo Eukaryotic cells feature a diverse and dynamic cytoskeletonThe Nucleus- The Nucleus is large and highly organized- STRUCTURE:o The nucleus is surrounded by a double-membrane nuclear envelopeo The nucleus has a distinct region called the nucleolus- FUNCTION:o Information storage and processing Contains the cell’s chromosomeso Ribosomal RNA synthesis (in the nucleolus)Rough Endoplasmic Reticulum- STRUCTURE:o The rough endoplasmic reticulum is a network of membrane-bound tubes and sacs studded with ribosomes The interior is called the lumeno The rough ER is continuous with the nuclear envelope- FUNCTION:o Ribosomes associated with the Rough ER synthesize proteinso New proteins are folded and processed in the Rough ER lumenSmooth Endoplasmic - STRUCTURE:o The smooth endoplasmic reticulum lacks the ribosomes associated with the rough ER- FUNCTION:o Enzymes within the smooth ER may synthesize fatty acids and phospholipids, or break down poisonous lipidso Reservoir for Ca 2+ ionsGolgi Apparatus- STRUCTURE:o The golgi apparatus is formed by a series of stacked flat membranous sacs called cisternaeo Cis- Closer to ERo Trans- faces the cell membrane- FUNCTION:o Processes, sorts, and ships proteins synthesized in the Rough ERo Membranous vesicles carry materials to and from the organelleRibosomes- STRUCTURE:o Non-membranous not considered organelleso Have large and small subunits, both containing RNA molecules and proteino Ribosomes can be attached to the rough ER or free in the cytosol, the fluid part of the cytoplasm- FUNCTION:o Protein synthesisPeroxisomes- STRUCTURE:o Globular organelles bound by a single membrane- FUNCTION:o Center of oxidation reactionso Specialized peroxisomes in plants called glyoxysomes are packed with enzymes that oxidize fats to form a compound that can be used to store energy for the cellLysosomes- STRUCTURE:o Lysosomes are single membrane-bound structures containing approximately 40 different digestive enzymeso Lysosomes are found in animal cells- FUNCTION:o Lysosomes are used for


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