LO12 - Cells_Eukaryotes(1).docx

NANYANG TECHNOLOGICAL UNIVERSITY Hello and Welcome In this online session,you will learn about Cells -Eukaryotes School of Biological Sciences At the end of the session,you should be able to: Define eukaryotic cell; Describe the cellular structures which are common to animal and plant cells; De...

NANYANG TECHNOLOGICAL UNIVERSITY Hello and Welcome In this online session,you will learn about Cells -Eukaryotes School of Biological Sciences At the end of the session,you should be able to: Define eukaryotic cell; Describe the cellular structures which are common to animal and plant cells; Describe how genetic materials (chromosomes)of eukaryotes are structured or packaged;and Explain the functions of main organelles like nucleus,ER system, Golgi apparatus,mitochondria,chloroplasts and the cytoskeletal system. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Eukaryotic cells are larger and more complex than prokaryotic cells. The size range among eukaryotic cells is much wider because of the diversity (from protists like paramecium to different NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Plasma membrane Cytoplasm NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Its internal membranes form compartments called organelles. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences The cytoplasm is contains a network of Cytoplasm (semi-fluid,with scaffold of cytoskeleton) Many organelles are immediately conspicuous under the microscope. Rough endoplasmic reticulum Nucleus Endomembrane System It gives rise to the internal membranes found in the cell and each compartment Nuclear envelope can provide specific Smooth endoplbsmic reticulum Secretory Vesicle Lysosome Nudeus Plasma membrane NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Not all eukaryotic cells are alike: The plasma membrane of animal cells contains cholesterol (but not those of e.g.,plant cells). The cells of plants,fungi,and many protists have a cell wall beyond the plasma membrane. All plants and many protists contain organelles called chloroplasts. Plants contain a central vacuole. Only animal cells contain centrioles. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Copyright The McGraw-Hill Companies,ine. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Cytoskeleton Microtubule- Intermediate filament Actin filament Cytoplasm Chloroplast Smooth endoplasmic reticulum Golgi complex Nucleus Nucleolus -Nuclear envelope Nuclear pore Rough endoplasmic reticulum Ribosomes Mitochondrion Peroxisome Plasmodesmata Plasma membrane Cell wall Adjacent cell wall Central vacuole Tonoplast Copyright The McGraw-Hill Companies,Inc, Which of the following does not have a cell wall? There may be more than one correct option.Please select all options that you think are correct,and then submit. A Animal cell B Plant cell C Bacterial cell Fungal cell D E Archaea cell Chloroplasts may be found in cells. There may be more than one correct option.Please select all options that you think are correct,and then submit. animal D B plant C D fungal protist E none of the above Only animal cells contain . There may be more than one correct option.Please select all options that you think are correct,and then submit. A vacuoles B lipopolysaccharide C centrioles D chloroplasts E endomembrane system NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences It is the command and control centre of the cell. It also stores hereditary information. The nuclear surface is bound by a double-membrane called the nuclear envelope. — Groups of proteins form openings called nuclear pores that permit proteins and ribonucleic acid (RNA)to pass in and out of the nucleus. containing membrane membrane chromatin Copyright The McGraw-Hill Companies,Inc. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences The DNA of eukaryotes is packaged into linear chromosomes. Chromosomal DNA is organised into nucleosomes which consist of a portion of DNA wrapped around proteins called histones. Copyright The McGraw-Hill Companies,Inc. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences When the cell is not dividing,the chromosomes exist as threadlike strands called chromatin. Whether the tails of histones are methylated (-CH₃ )or acetlyated (-COCH₃ )determines whether the chromatin exists as heterochromatin (more densely compacted)or euchromatin (less densely compacted)respectively. Chromosome Territories Nucleus Chromatin DNA me me Nucleosome deacetylated histone tails DNA Heterochromatin Methylated DNA acetylated histone tails nucleosome Euchromatin Unmethylated DNA NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences A region of the nucleus called the nucleolus is the site where ribosomes are assembled. Ribosomes are structures that build up proteins and consist of ribosomal RNA and several different kinds of proteins. Nucleolus - Ribosomes are assembled here Copyright The McGraw-Hill Companies,Inc. The genomic DNA of eukaryotes are organised into chromosome(s). There may be more than one correct option.Please select all options that you think are correct,and then submit. B circular C linear D unwound E none of the above refers to more densely compacted chromosomes while refers to less densely compacted ones. There may be more than one correct option.Please select all options that you think are correct,and then submit. C Histones;chromatin D Heterochromatin;euchromatin E Euchromatin;heterochromatin NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences The endomembrane system refers to the collection of internal membranes in the cell that make up organelles such as endoplasmic reticulum,Golgi complex,lysosomes and vacuoles. Some of the membranes form channels and interconnections. Other portions become isolated spaces enclosed by membranes,known as vesicles. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences The endoplasmic reticulum (ER)is an extensive system of internal membranes. The portion of the ER dedicated to protein synthesis is called the rough ER. The surface of this region looks pebbly. The rough spots are due to embedded ribosomes. The portion of the ER that aids in the manufacture of carbohydrates and lipids is called the smooth ER. Rough endoplasmic reticulum Smooth endoplasmic reticulum Copyright The McGraw-Hill Companies,Inc. The surface of this region looks smooth because embedded ribosomes are scarce. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences After synthesis in the ER,the newly-made molecules are passed to the Golgi bodies. Golgi bodies are flattened stacks of membranes scattered through the cytoplasm. Their numbers vary depending on the cell. Their function is to collect,package, and distribute molecules manufactured in the cell. The Golgi bodies of a cell are collectively called the Golgi complex. Copyright The McGraw-Hill Companies,Inc. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences The Golgi complex also gives rise to lysosomes. These membrane-bound structures contain enzymes that the cell uses to break down macromolecules. - The worn-out cell parts are broken down and their components recycled to form new parts. The particles that the cell has ingested are also digested. possibly ysosomes Transport vesides (a)Secretory vesides (b) Veside 0.57μm Copyright The McGraw-Hill Companies,Inc. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Vacuole Vacuoles are membrane-bound storage compartments. In plants,the central vacuole stores water and dissolved substances. In some protists,the contractile vacuole is found near the cell surface of some protists and accumulates excess water from inside the cell that it then pumps out. Central vacuole Which of the following is/are not part of the endomembrane system? There may be more than one correct option.Please select all options that you think are correct,and then submit. C Nucleosomes reticulum D Rough endoplasmic E Ribosomes What is/are the difference(s)between a rough and a smooth endoplasmic reticulum? There may be more than one correct option.Please select all options that you think are correct,and then submit. A The chemical nature of the membranes. Only the rough endoplasmic reticulum is interconnected. Newly synthesized molecules are passed from the endoplasmic reticulum to the There may be more than one correct option.Please select all options that you think are correct,and then submit. A nucleolus B ribosomes C membrane D Golgi bodies E none of the above NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Eukaryotic cells contain energy harvesting organelles that contain their own sets of DNA. These organelles appear to have been derived from ancient bacteria that were taken up by other prokaryotic cells,which may then have evolved to become eukaryotic cells. They include mitochondria and chloroplasts. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Mitochondria Mitochondria are cellular powerhouses. They are the sites for chemical reactions called oxidative metabolism. The organelle is surrounded by two membranes (inner and outer membranes). Outer membrane Inner membrane Crista Matrix Copyright The McGraw-Hill Companies,Inc. Chloroplast (found only in photosynthetic organisms) Chloroplasts are the sites of photosynthesis. The organelle is also surrounded by two membranes (inner and outer membranes). Outer membrane Inner membrane Granum Thylakoid Stroma Copyright The McGraw-Hill Companies,Inc. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Both mitochondria and chloroplasts possess their own molecule of circular DNA. They cannot be grown free of the cell. Totally dependent on the cells within which they occur. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences The Theory of Endosymbiosis States that some organelles evolved from a symbiosis in which one cell of a prokaryotic species was engulfed by and lived inside of a cell of another species of prokaryote (that was a precursor to eukaryotes). The engulfed species provided their hosts with advantages because of special metabolic activities. The modern organelles of mitochondria and chloroplasts are believed to have evolved from these endosymbiotic prokaryotes. Mitochondrion is the site for whereas chloroplast is the site for . There may be more than one correct option.Please select all options that you think are correct,and then submit. D oxidative metabolism;photosynthesis E vesicular transport;protein synthesis What is/are the feature(s)common to mitochondria and chloroplasts? There may be more than one correct option.Please select all options that you think are correct,and then submit. E None of the above Which of the following features suggest(s)the endosymbiotic origin of mitochondria and chloroplasts? There may be more than one correct option.Please select all options that you think are correct,and then submit. A The organelles have folded inner membrane. D The organelles are small. E None of the above NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences The cytoskeleton is comprised of an internal framework of protein fibres that: —Anchors organelles to fixed locations; —Supports the shape of the cell;and —Helps organise ribosomes and enzymes needed for synthesis activities. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences The cytoskeleton is comprised of three different types of protein fibres: Intermediate filaments Thick ropes of intertwined Microtubules Hollow tubes made up of the protein tubulin. Microfilaments Long,slender microfilaments made up of the protein actin. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Centrioles are complex structures that assemble microtubules in animal cells and the cells of most protists. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Cellular motion is associated with the movement of actin microfilaments and/or microtubules. Some cells "crawl"by coordinating the rearrangement of actin microfilaments. Some cells swim by coordinating the beating of microtubules grouped together to form flagella or cilia. Flagella and Cilia Copyright The McGraw-Hill Companies,Inc. NANYANG TECHNOLOGICAL UNIVERSITY Which of the following is/are cytoskeleton? There may be more than one correct option.Please select all options that you think are correct,and then submit. A Chromatin B Actin filaments C Microtubules D Lysosome E Intermediate filaments Both flagella and cilia are composed of physical arrangement differs. , although their A tubulin B chromatin C centriole D endoplasmic reticulum E none of the above NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Summary:Eukaryotic cell organelles and their functions Structure Structural Elements Cell Wall Cytoskeleton Flagella and cilia Plasma Membrane and Plasme membrane Endoplasmic reticulum Nucleus Description Outer layer of cellulose or chitin absent in animal cells Network of protein filaments Cellular extensions with certain arrangement of pairs of microtubules Endomembrane System Organelles Lipid bilayer in which proteins are embedded Network of internal membranes Structure (usually spherical) that contains chromosomes; surrounded by double membrane Protection;support Structural support;cell movement Mobility or moving fluids over surfaces Regulates what passes into and out of cell;cell-to-cell recognition Forms compartments and vesicles; participates in protein and ipid synthesis Control center of cell;directs protein synthesis and cell reproduction V NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Summary:Eukaryotic cell organelles and their functions Stacks of flattened vesicles Vesicles derived from Golgi complex that contain hydrolytic digestive enzymes Organelles Bacteria-like elements with double membrane Bacteria-like organelles found in plants and algae;complex inner membrane that consists of stacked vesicles of Gene Expression Long threads of DNA that form a complex with protein Nucleolus Site of genes of rRNA synthesis Assembles ribosomes Ribosomes Small,complex assembles of protein and RNA,often bound to endoplasmic reticulum Sites of protein synthesis ▼ NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences In this section on Eukaryotic cells,you need to take home the following messages: 1.Eukaryotic cells are larger and more complex than prokaryotic cells. 2.Not all eukaryotic cells are alike,e.g.,there are differences between animal and plant cells,between plant and fungal cells etc. 3.A eukaryotic cell has a membrane-bound nucleus,and the linear chromosomes are organised into densely packed nucleosomes. 4.The endomembrane system consists of the rough and smooth endoplasmic reticulum,Golgi complex and associated vesicles and vacuoles.These are the sites of biosynthesis and molecular trafficking. NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences In this section on Eukaryotic cells,you need to take home the following messages: 5.Eukaryotic cells contain energy harvesting organelles that contain their own DNA-mitochondria that process chemical energy through oxidative metabolism,and chloroplasts that process light energy. 6.The cytoskeleton system acts as the interior framework of a cell. 馋章卷 NANYANG TECHN OLOGICAL UNIVERSITY Self-Assessment Cells:Eukaryotes Total number of questions:8 BEGIN TEST Cholesterol can be found in the plasma membrane of cells but not in that of cells. A plant; fungal B animal; plant C fungal; animal D E plant; animal fungal; plant School of Biological Sciences Self-Assessment The tails of histones are modified through and in order to regulate the compacting status of chromatin. There may be more than one correct option.Please select all options that you think are correct,and then submit. C acetylation;methylation ribosomes;membranes D E cell walls;centrioles NANYANG TECHNOLOGICAL UNIVERSITY School of Biological Sciences Self-Assessment There is a high concentration of assembled at the nucleolus. There may be more than one correct option.Please select all options that you think are correct,and then submit. A chromatin B nucleosomes C membranes D histones E ribosomes School of Biological Sciences Self-Assessment Which of the following correctly depict(s)the flow of synthesized molecules within a cell? There may be more than one correct option.Please select all options that you think are correct,and then submit. D Rough ER→Golgi complex →lysosome E none of the above School of Biological Sciences Self-Assessment The of plant cells stores water and solutes. There may be more than one correct option.Please select all options that you think are correct,and then submit. A cell wall B chloroplast C central vacuole Golgi complex D E Mitochondria Label the following components shown in the figure: Drag the options into the correct category,and then submit. Mitochondrion School of Biological Sciences Self-Assessment Match the correct option to the figures below: Drag the options into the correct category,and then submit. Process Chloroplast Cells that crawl generally achieve that by of . There may be more than one correct option.Please select all options that you think are correct,and then submit. A movement;flagella B coordination;cilia C rearrangement;actin microfilaments D E coordination;ribosomes none of the above School of Biological Sciences Self-Assessment Youve completed the Self-Assessment. Your score is 75%