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Download Lecture 4 - Pasadena City College
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Cell Structure and Function Kandinsky (1866-1944) Early Observations • Santiago Ramon y Cajal (1852-19340 Early Discoveries • Mid 1600s - Robert Hooke cells in cork • Late 1600s - Antony van Leeuwenhoek, microorganisms Early Discoveries • 1820s - Robert Brown observed nucleus in plant cells Microscopes • Light microscopes Figure 4.1B LM 1,000 • Magnify to 1,000X Electron Microscope Figure 4.1C TEM 2,800 SEM 2,000 • Greater magnification Figure 4.1D Cell Size 10 m 100 mm (10 cm) Length of some nerve and muscle cells Chicken egg Unaided eye 10 mm (1 cm) Frog egg 1 mm 100 m Most plant and animal cells 10 m Nucleus Light microscope Most bacteria 1 m 100 nm Mitochondrion Mycoplasmas (smallest bacteria) Viruses Ribosome 10 nm Proteins Lipids 1 nm Small molecules 0.1 nm Atoms Electron microscope • Cells vary • Surface area - limits Human height 1m Cell Size – Ratio of surface area to volume 10 m 30 m 30 m Figure 4.2B Surface area of one large cube 5,400 m2 10 m Total surface area of 27 small cubes 16,200 m2 Cell Theory 1) Every organism is composed of cells 2) Cell is smallest unit of life 3) Continuity of life from cells growth + division Structure of Cells • Two types • Prokaryotic bacteria – No nucleus – DNA? Prokaryotic flagella Ribosomes Capsule Cell wall Plasma membrane Nucleoid region (DNA) Pili Structure of Cells • Eukaryotic – plants, animals, fungi – DNA? Structure of Cells Colorized TEM 15,000 Prokaryotic cell Nucleoid region Nucleus Eukaryotic cell Organelles Eukaryotic Cells • Nucleus and organelles Rough endoplasmic reticulum Smooth endoplasmic reticulum Nucleus Flagellum Not in most plant cells Lysosome Ribosomes Centriole Peroxisome Microtubule Cytoskeleton Golgi apparatus Plasma membrane Intermediate filament Mitochondrion Microfilament Plant Cell Features Nucleus Rough endoplasmic reticulum Ribosomes Smooth endoplasmic reticulum Golgi apparatus Not in animal cells Microtubule Central vacuole Intermediate filament Chloroplast Microfilament Cell wall Mitochondrion Peroxisome Plasma membrane Cytoskeleton Components of the Nucleus Chromatin Nucleolus Nucleus Two membranes of nuclear envelope Pore Rough endoplasmic reticulum Ribosomes Smooth ER Smooth ER Rough ER Nuclear envelope Ribosomes Figure 4.7 Rough ER TEM 45,000 Smooth ER Rough ER Transport vesicle buds off 4 Ribosome 3 Secretory (glyco-) protein inside transport vesicle Sugar chain 1 2 Glycoprotein Polypeptide Rough ER Golgi Apparatus Golgi apparatus Golgi apparatus Transport vesicle from ER New vesicle forming “Shipping” side of Golgi apparatus Transport vesicle from the Golgi TEM 130,000 “Receiving” side of Golgi apparatus Vesicles • Lysosomes • Vacuoles Vesicles – Central vacuole – Contractile vacuole Nucleus Nucleus Colorized TEM 8,700 Central vacuole Contractile vacuoles LM 650 Chloroplast Mitochondria Mitochondrion Outer membrane Inner membrane Cristae Matrix TEM 44,880 Intermembrane space Chloroplasts Chloroplast Inner and outer membranes Granum Intermembrane space Figure 4.14 TEM 9,750 Stroma Figure 4.17A LM 600 Colorized SEM 4,100 Flagella and Cilia Figure 4.17B Flagella and Cilia Flagellum Electron micrographs of cross sections: Outer microtubule doublet TEM 206,500 Central microtubules Radial spoke Dynein arms Flagellum Figure 4.17C Basal body (structurally identical to centriole) TEM 206,500 Plasma membrane Basal body Cytoskeletal Elements Tubulin subunit Actin subunit Fibrous subunits 25 nm 7 nm Microfilament 10 nm Intermediate filament Microtubule Microtubules tubulin subunit • Involved in plant/ animal interactions Figure 4.21 Page 71 Microfilaments • Muscle contraction actin subunit Intermediate Filaments one polypeptide chain Plant Cell Walls • Primary cell wall = outer • Secondary cell wall – Rigid – Cellulose and lignin • Middle lamella joins cells together Plant Cell Walls Secondary cell wall (3 layers) Primary cell wall Plant Cell Walls plasmodesmata plasma membrane middle lamella primary cell wall Figure 4.27b Page 74 Slide 35 Animal Cell Junctions • Tight junctions – Link cells of most body tissues – Waterproof • Adhering junctions – Link cells prone to stretching • Gap junctions – Link cytoplasm - rapid signals Animal Cell Junctions tight junctions adhering junction gap junction Question of the Day What is the role of the smooth ER in increasing drug tolerance?
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