Lecture 2: Eukaryotic Cells & The Cytoplasm (PDF)

9/11/2017 Lecture 2 : Eukaryotic Cells & The Cytoplasm At the end of this lecture, students should be able :  To distinguish the general features of prokaryotic and eukaryotic cells.  To discuss the cytoplasm and the organelles.  To descr...

9/11/2017 Lecture 2 : Eukaryotic Cells & The Cytoplasm At the end of this lecture, students should be able :  To distinguish the general features of prokaryotic and eukaryotic cells.  To discuss the cytoplasm and the organelles.  To describe cell surface specializations and tell how they help cells survive.  To explain the two basic varieties of cells. 1  9/11/2017  Have a nucleus and other organelles  Larger and generally more complex  Eukaryotic organisms  Plants  Animals  Protistans  Fungi Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. cell flagella Prokaryotic cell: simple Eukaryotic cell: complex internal structure internal structure 2  9/11/2017 Animal cell (eukaryotic) DNA in nucleus cytoplasm plasma membrane Fig. 2.2c,  Have a system of internal membrane-bounded structures  DNA in nucleus; forms multiple chromosomes linear and complexed with proteins  Nucleus bounded by the nuclear envelope  Eukaryotes have 80S ribosomes, each consisting of a small (40S) and large (60S) subunit. 3  9/11/2017 N UC LEU S C YTO SK ELETO N R IB O S O M E S M IT O C H O N D R IO N ROUGH ER SM OOTH ER C E N T R IO L E S GOLGI BODY PLASM A LYSO SO M E M EM BR AN E 4  9/11/2017  Viscous fluid containing all cell organelles except the nucleus  Means living gel (plasm) of the cell (cyto)  Major components are : cytosol, organelles and inclusions  Fluid part : 75% water and 25% proteins  The proteins (enzymes, structural proteins) make the cytoplasm viscous  Nonprotein molecules (ions, ATP)  The nucleus and ribosomes  Organelles of endomembrane system  The energy-related organelles  The cytoskeleton 5  9/11/2017  A control center of the cell that encloses the chromosomes and 1 or more nucleoli  Spherical structure bounded by a double membrane  The nucleus is a highly specialized organelle that serves as the information processing and administrative center of the cell 6  9/11/2017 Functions :  Keeps the DNA molecules of eukaryotic cells separated from metabolic machinery of cytoplasm / Stores the cell's hereditary material (DNA)  Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells  Coordinates the cell's activities Nuclear envelope Nuclear pore Nucleolus Chromatin 7  9/11/2017  Two outer membranes (lipid bilayers)  Innermost surface has DNA attachment sites  Pores span bilayer one of two lipid bilayers (facing nucleoplasm) nuclear pore (protein complex one of two lipid bilayers NUCLEAR that spans both lipid bilayers) (facing nucleoplasm) ENVELOPE  Permit passage of ribosomal subunit and mRNA out of the nucleus into the cytoplasm and passage of proteins from cytoplasm into the nucleus 8  9/11/2017  Dense mass of material in nucleus  May be one or more  To synthesis and assembly of ribosomes  Visible when cell is not dividing  Contains RNA for protein manufacture  Subunits must pass through nuclear pores to reach cytoplasm  Cell’s collection of DNA and associated proteins  Chromosome is one DNA molecule and its associated proteins  Shortened, thickened structures that formed by DNA associated with protein as a cell begins to divide.  Appearance changes as cell divides  Sites of heredity information. 9  9/11/2017 Components Functions Nuclear envelope Outer boundary of the nucleus Nuclear pores Allows substances to move in and out of the nucleus Nucleolus Produces ribosomal subunits Chromatin Becomes chromosomes and contains DNA, organized into genes 10  9/11/2017  Group of related organelles in which lipids are assembled and new polypeptide chains are modified  Products are sorted and shipped to various destinations  Endoplasmic reticulum  Golgi bodies  Vesicles 11  9/11/2017  In animal cells, continuous with nuclear membrane  Extends throughout cytoplasm  Two regions: Rough ER and Smooth ER  Arranged into flattened sacs  Ribosomes on surface give it a rough appearance  Some polypeptide chains enter rough ER and are modified  Cells that specialize in secreting proteins have lots of rough ER 12  9/11/2017  No ribosomes on surface  A series of interconnected tubules  Lipids assembled inside tubules  Smooth ER of liver inactivates wastes, drugs  Golgi apparatus  Stack of flattened saccules  Transfer station  Receives vesicles from ER  Modifies molecules  Sorts and repackages for new destination ▪ Some are lysosomes  Lysosomes  Vesicles that digest molecules or portions of the cell  Digestive enzymes 13  9/11/2017 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. rough ER smooth ER transport vesicle transport vesicle lysosomes Golgi apparatus secretory incoming vesicle vesicle Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer. 14  9/11/2017  Membranous sacs that move through the cytoplasm ▪ Lysosomes ▪ Peroxisomes ▪ Central Vacuole 15  9/11/2017  ATP-producing powerhouses  Double-membrane system  Carry out the most efficient energy- releasing reactions  These reactions require oxygen  Outer membrane faces cytoplasm  Inner membrane folds back on itself  Membranes form two distinct compartments  ATP-making machinery is embedded in the inner mitochondrial membrane 16  9/11/2017  Convert sunlight energy to ATP through photosynthesis  Chloroplasts ▪ Use solar energy to synthesize carbohydrates ▪ Only in plants ▪ Three-membrane system ▪ Double membrane enclosing stroma  Thylakoids formed from third membrane ▪ Thylakoid membrane contains pigments that capture solar energy. 17  9/11/2017  Both mitochondria and chloroplasts resemble bacteria  Have own DNA, RNA, and ribosomes 18  9/11/2017  Present in all eukaryotic cells  Basis for cell shape and internal organization  Allows organelle movement within cells and, in some cases, cell motility (flagella, cilia) intermediate filament microtubule microfilament 19  9/11/2017  Attach to tubulin and actin  Motor proteins  Crosslinking proteins  Microtubules  Small, hollow cylinders  Assembly controlled by centrosome  Help maintain cell shape and act as trackways  Intermediate filaments  Intermediate in size  Ropelike assembly  Runs from nuclear envelope to plasma membrane 20  9/11/2017 Microtubules Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. microtubule centrosome nucleus Actin filaments 2 chains of monomers twisted in a helix Forms a dense web to support the cell microvilli actin filaments nucleus 21  9/11/2017  Motor proteins  Instrumental in allowing cellular movements  Myosin ▪ Interacts with actin ▪ Cells move in amoeboid fashion ▪ Muscle contraction  Kinesin and dynein ▪ Move along microtubules ▪ Transport vesicles from Golgi apparatus to final destination Figure 4.18 Motor proteins Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. vesicle kinesin ATP receptor kinesin microtubule vesicle moves, not microtubule b. Kinesin 22  9/11/2017  Centrioles  Made of 9 sets of microtubule triplets  Two centrioles lie at right angles  In animal cells, not present in plant cells Figure 4.19 Centrioles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. one microtubule triplet centrosome one pair of centrioles in a centrosome Courtesy Kent McDonald 23  9/11/2017  Eukaryotes  For movement of the cell or fluids past the cell  Similar construction in both ▪ 9+2 pattern of microtubules  Cilia shorter and more numerous than flagella Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 4.20 Cilia and flagella cilia in bronchial wall flagella of sperm a. Flagellum cross section Flagellum central microtubules microtubule doublet dynein side arms TEM 350,000 plasma membrane TEM 101,000 triplets Basal body Basal body b. cross section a(cilia): © Manfred Kage/Peter Arnold; (sperm): © David M. Phillips/Photo Researchers, Inc.; b: (flagellum, basal body): © William L. Dentler/BPS 24  9/11/2017  Some free-living cells, such as amoebas, form pseudopods (“false feet”)  These temporary, irregular lobes project from the cell and function in locomotion and prey capture  Pseudopods move as microfilaments elongate inside them – motor proteins attached to the microfilaments drag the plasma membrane with them 25  9/11/2017 Centrioles  Pairs of cylindrical microtubular structures found in the cytoplasm of animal cells that play a role in cell division.  Eukaryotic cell walls  Matrixes between animal cells  Cell junctions 26  9/11/2017 Plasma membrane  Structural component that wraps around the plasma membrane  Occurs in plants, some fungi, some protistans Primary cell wall of a young plant  Animal cells have no cell walls  Some are surrounded by a matrix of cell secretions and other material 27  9/11/2017 Two major subcompartments :  Interstitial Fluid (ISF) surrounds the cells, but does not circulate. It comprises about 3/4 of the ECF.  Plasma circulates as the extracellular component of blood. It makes up about 1/4 of the ECF. Two minor subcompartments :  Transcellular fluid is a set of fluids that are outside of the normal compartments. These 1 - 2 liters of fluid make up the digestive juices, mucus, etc.  Lymph is a clear fluid circulates around the body tissues, containing lymphocytes. Originated from blood plasma. 28  9/11/2017  Plants  Plasmodesmata  Animals  Tight junctions  Adhering junctions  Gap junctions fre e s u rfa c e o f e p ith e lia l tis s u e (n o t a tta c h e d to a n y o th e r tis s u e ) e x a m p le s o f p ro te in s th a t m a k e u p tig h t ju n c tio n s gap ju n c tio n s a d h e rin g ju n c tio n b a s e m e n t m e m b ra n e 29  9/11/2017  Junctions between cells  Adhesion junctions ▪ Internal cytoplasmic plaques joined by intercellular filaments ▪ Sturdy but flexible sheet of cells 30  9/11/2017 Figure 4.23 Junctions between cells of the intestinal wall Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. plasma membranes cytoplasmic plaque filaments of cytoskeleton intercellular filaments intercellular space a. Adhesion junction a. From Douglas E. Kelly, Journal of Cell Biology, 28 (1966:51). Reproduced by permission of The Rockefeller University Press Plasma membrane proteins attach to each other Zipperlike Cells of tissues that serve plasma as barriers membranes tight junction proteins intercellular space b. Tight junction Figure 4.23 continued Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 31  9/11/2017 plasma membranes Gap junctions Allow cells to membrane channel communicate through plasma membrane channels Lends strength while allowing small molecules and ions to pass through Intercellular space c. Gap junction Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Figure 4.23 continued Junction Structure Function Gap Two identical plasma Allows small membranes join molecules and ions together, lined by pass through them. membrane channel proteins Tight Plasma membrane  Hold the cells together attach to each other  Barrier functions, produce zipperlike example-hold urine in fastening kidney tubules Adhesion Internal cytoplasmic plaques They hold cardiac joined by intercellular muscle cells tightly together filaments as the heart expands and contracts. They hold epithelial cells together. 32  9/11/2017  Body cells  By mitosis; differentiated into special cell types  Arrangements of the elements in cells varied so that they can carry out various jobs such as digestion, energy storage or oxygen transport to your tissues  Sex cells  Specialized cells that are used for reproduction.  Sexual reproduction combines genetic material from two organisms and requires meiosis. 33