Chapter 4: Cell Structure

1. Chapter 4: Cell Structure Topics you are not responsible for: Bacterial cell walls and the Archaea Cell-to-cell interactions End of Chapter questions: Understand: all Apply: all Synthesize: 1, 3, 4 Do all mQuiz questions Inner Life of The Cell TEM of Platinum/Carbon replicas of HeLa cell cytoplasm showing clathrin-coated vesicles and microtubules Cell Structure

2. What happens to Ab after it forms? External Amyloid plaques Internal Neurofibrillary tangles -- Tau protein “Trafficking” of membrane components Exportto cell surface -- APP, secretases, etc. Import into cell Questions Do plaques and/or tangles cause Alzheimer’s Dis.? Why do neuro. tangles form? Cell Structure

3. B A C Fluorescence Light Microscopy (A-C) Bright Field DIC DIC Video Electron Microscopy E D Confocal 3D imaging TEM SEM Cell Structure

4. Examples of Light Microscopy A. Standard Bright Field Microscopy of Histological section of brain stained to show Neurofibrillary Tangles (>) and Aβ plaques (*). http://www.microscopy-uk.org.uk/mag //artsep06/mc-Alzheimer.html B. DIC (Differential Interference Microscopy) of Neocortical neurons in primary culture. Note accentuation of edges and 3D-like appearance Adapted from http://www.ipmc.cnrs.fr/cgi-bin/standard.cgi?descriptif=mantegazza.txt&dossier1=equipes&dossier2=mantegazza&site=inter&menu=1&ssmenu=14&lang=uk C. Fluorescence Microscopy of fibroblast cell culture stained for proteins of the nucleus, mitochondria, and peroxisomes, as well as the filamentous actin and intermediate filaments.http://learn.hamamatsu.com/galleries/ digitalimages/muntjac/muntjaclarge10.html Examples of Electron Microscopy D. TEM (Transmission Electron Microscopy) of neurons (cross-section) showing internal cellular structures. ttp://visualsunlimited.photoshelter. com/image/I00005SIGjGWwl9U E. SEM (Scanning Electron Microscopy) of neurons showing external surface structures. http://www.med.nus.edu.sg/ant/histonet/txt/nervsem/nerv03.sem.html Cell Structure

5. Eukaryotic cell cytoplasm How do Eukaryotic cells differ from Prokaryotic cells? Prokaryotes = bacteria Eukaryotes = everything else Size Cytoplasm organization Structure of chromosomes We will discuss other differences later Cell Structure

6. How big are cells? Why are cells so small? Surface to volume (S/V) ratio How Big is It? Question Cell Structure

7. What are some functional regions of cells? Cytoplasm Cell membrane (plasma membrane) Extracellular structures Cell wall Cilia & flagella EC matrix Cell Structure

8. What are the components of eukaryotic cytoplasm? Membrane bound compartments -- Cytoplasm vs “cytosol” Molecular building blocks Proteins/enzymes -- Cytoskeleton Ribosomes Cell Structure

9. What is the structure of the nucleus? Large nuclear pores -- two membranes Chromosomes Nucleolus Cell Structure

10. How do molecules move through the cell? Diffusion through cytosol Endomembrane transport system What is transported? Where to? Molecular Diffusion Know this! Rev Question Cell Structure

11. What is the structure and function of the ER? Beginning of endomembrane transport Rough ER Protein: -- synthesis (Ribosomes) -- folding -- modifications (glycosylation) Smooth ER Lipid synthesis Ca++ storage Transport to Golgi Transport vesicles Cell structure Cell Structure

12. Cis Face Trans Face What is the structure & function of the Golgi? Protein glycosylation Packaging Transport to: Lysosomes Cell membrane Cell exterior (secretion) View these animation Virtual cell -- Protein Trafficking Virtual cell – Protein modification Links on Class resource page Question Cell Structure

13. What is the function of lysosomes? Breakdown of: Intracellular materials Extracellular materials How are materials transported to lysosome? Hydrolases from Golgi Materials from inside and outside the cells Cell Structure

14. Mutations to lysosome function underlie some genetic diseases? • I-cell diseases • Mental retardation • Metabolic abnormalities • Fatal • Mucolipidosis II • Accumulation of lysosomes • Hydrolase targeting incorrect • - Secreted to cell exterior • Tay-Sacks disease • Deficiency in a lipase • ganglioside GM2 (lipid) accummulates Lymphocytes of Mucolipidosis II Question Cell Structure

15. What are functions of chloroplasts and mitochondria? What are distinctive properties Double membrane Presence of DNA What is the origin of these organelles? “Endosymbiosis” 70S vs 80S ribosomes Endosymbiosis Cell Structure

16. What proteins comprise the cell cytoskeleton? • Intermediate filaments • Microtubules • Actin filaments • How is the “cytoskeleton” different • from a animal skeleton? • Organization and function • of Intermediate filaments • Mechanical strength Cell Structure

17. What are the organization and functions of microtubules? cytoplasmic transport chromosome movements movements of flagella and cilia -- “9+2” structure Bacterial flagella are different Cytoplasmic streaming Closer view on microtubules Flagella Cilia Cell Structure

18. What are the organization and • functions of actin filaments? • Various types of cell movements • Membrane contractions • muscle contraction • Crawling motions • Interacts with “myosin” Membrane ruffling Heart Cell Cell Structure

19. How do plant cells differ from animal cells? Chloroplasts Cell Wall Vacuole Cell Structure

20. How are viruses different from cells? Much smaller Protein coat – ‘capsid’ Often no membrane No metabolism Rev. Question Cell Structure