LS2 Lec 2 Cell (4 Slides)

LS2 Lec 2 Cell (4 Slides) - What Are Cells Made of? Life...

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Unformatted text preview: What Are Cells Made of? Life Sciences 2 Cells: The Working Units of Life Chapter 5 Dr. Joseph Esdin The Basic Unit of Life • Life requires a structural compartment separate from the external environment in which macromolecules can perform unique functions in a relatively constant internal environment • These “living compartments” are cells Robert Hooke • Hooke’s Law: F = -Kx • Most famous for his study of thin slice of cork under the microscope 1 Robert Hooke • Celluae • The term “cells” Cell Theory Antoni van Leewenhoek • Known as the father of microbiology • Improved the microscope • First to report single celled organisms • animalcules Cell Theory • Matthias Schleiden observed plant cell and made the first statement of the cell theory • All organisms are composed of cells • Theodor Shwann reported the same in animal cells • All cells come from preexisting cells • Cells are the fundamental units of life 2 Multicellular Organisms • Division of labor • Cells Must stick together Cell Size • Resolution .2 mm • Unaided eye: • Light Microscopy • Cells must communicate with each other .2µm • Electron Microscopy .5 nm What Limits Cell Size? What Limits Cell Size? Spheres 1µ m 2 µm 4 µm Surface area 4 ! r2 3.14 µ m2 12.56 µm2 28.26 µm2 Volume 4/3 ! r3 0.52 µ m3 4.19 µ m3 14.18 µm3 6:1 3:1 2:1 Surface areato-volume ratio smaller means that it c an exchange with its environment more than it can process so more effi cient 3 Eukaryotes • • • • Membrane-Nucleus Membrane-organelles Unicellular/Multicellular Larger What Functions Are Required to Ensure Cells Survival? • Obtain energy • Express genetic material (proteins synthesis) • Process biochemical reactions • Eliminate waste products Prokaryotes • Prokaryotes • No nucleus • No membraneorganelles • Unicellular • Smaller Rough endoplasmic reticulum Eukaryotic Cells Nucleus Microfilament Plasma membrane Smooth endoplasmic Reticulum Lysosome Mitochondrion Endocytotic vesicle Centriole Golgi complex Microtubule Ribosomes Cytosol Exocytotic vesicle 4 Plasma Membrane Plasma Membrane (Extra cellular fl uid) • Continuous • Lipid bilayer • Proteins ECF (water) Lipid bilayer Polar heads (hydrophilic) Lipid bilayer Nonpolar tails(hydrophobic) Intracellular fluid Polar heads (hydrophilic) ICF (water) Extracellular fluid Plasma Membrane Plasma Membrane Glycoproteins Choline Choline Phosphate Phosphate - Glycerol glycerol Fatty acid fatty acid Cholesterol Proteins 5 Plasma Membrane Integral proteins Peripheral proteins The Endomembrane System • Endoplasmic reticulum (ER) • Golgi apparatus Functions of the Plasma Membrane • Acts as a selectively permeable barrier • Is an interface for cells where information is received from adjacent cells and extracellular signals • Allows cells to maintain a constant internal environment • Has molecules that are responsible for binding and adhering to adjacent cells Rough Endoplasmic Reticulum • Membrane-bounded flattened sacs • Fluid filled vesicles • Functions in protein synthesis • Attached to nucleus • Studded with ribosomes • Lumen where protein synethesis occurs 6 Smooth Endoplasmic Reticulum • Lacks ribosomes • Contains enzymes important for lipid synthesis • Important in metabolism of drugs and alcohol • Hydrolysis • Storage of ions transport v esicles from ER cis The Golgi Apparatus • Consists of flattened membranous sacs and small membrane-enclosed vesicles • Receive proteins from the ER and further modify them • Concentrate, package, and sort proteins before they are sent to their destinations • Some polysaccharides for plant cell walls are synthesized Golgi Apparatus Golgi Apparatus ECF docking Docking at at 4 plasma plasma membrane Plasma membrane membrane cisternae Golgi complex 3 Uncoating uncoating Budding from 2 budding from Golgi Nucleus finished product Cytosol golgi Secretory secretory 1 vesicle v esicle Formation Golgi lumen Membrane of outermost Golgi sac formation 7 Cnidarians Physalia physalia Nematocyst Tentacles Cnidocytes Cnidocytes class hydrozoa colonized polyps Jellyfish Stylets Nematocyst toxins are peptides Fate of Proteins • Proteins are made in the RER • Shipped to Golgi for modification and packaging • Proteins are sent to the cell membrane or cytosol Ubiquitintagged protein E1 E2-E3 Individual amino acids Fragments of various lengths Summary of the Process proteasome break peptide bonds between amino acids that the cell can use 8 Question? Nucleus • How are proteins different from other macromolecules? • When do proteins become nonfunctional? Nuclear envelope Nucleolus Chromatin Nuclear Pores Nucleus • • • • Genetic Information Houses the genetic material (DNA) Double layered nuclear membrane Membrane contains nuclear pores Contains fluid called nucleoplasm that contains – Nucleolus: Where ribosomes are synthesized – Chromatin: DNA and proteins Nuclear Lamina 9 Lysosomes Lysosomes Inside of cell Golgi apparatus Plasma membrane Food particles taken in by phagocytosis • Originates from the Golgi apparatus • Contains lots of enzymes • Breakdown of food and foreign material brought into the cell by phagocytosis • Forms secondary lysosomes • Sites where digestion of spent cellular components occurs (autophagy) Outside of cell Organelles and Medicine Mitochondria • Tay-Sachs Disease: – Lipid accumulate in lysosomes of nerve cells in the brain – Genetic disease – Gangliosides (fatty acid derivative) – Hexosaminidase A Intermembrane space Cristae Outer Membrane Inner membrane Cristae Matrix Proteins of electron transport system where energy is formed 10 Mitochondria • Convert the potential chemical energy of fuel molecules into a form that the cell can use (ATP) • The production of ATP is called cellular respiration Mitochondria • Elongated fluid filled sacs • Can reproduce • Double membrane • Extensive folding of inner membrane own circular DNA Organelles that Process Energy • Chloroplasts, the sites where photosynthesis occurs, are one type of plastid Other Organelles • Peroxisomes, also called microbodies, are small organelles that are specialized to compartmentalize toxic peroxides and break them down • Glyoxysomes are structurally similar organelles found in plants 11 The Cytoskeleton • Maintains cell shape and support • Provides the mechanisms for cell movement • Acts as tracks for “ motor proteins” that help move materials within cells. • Three major types: – Microfilaments – intermediate filaments – microtubules Cytoskeleton Plasma membrane Ribosome on RER Free ribosomes Endoplasmic reticulum Microfilament The Cytoskeleton • Microfilaments: – Cell contraction – Structure to the plasma membrane Mitochondrion Microtubule Intermediate filaments The Cytoskeleton • Intermediate filaments: – Stabilize and resist tension 12 The Cytoskeleton Microtubules • Hollow Cylinders – Tracks Dynein Kinesin Microtubules Microtubules 9+2 arrangement Flagella cilia 13 Extracellular Structures Extracellular Structures • Multicellular animals have an extracellular matrix composed of fibrous proteins, such as collagen, and glycoproteins • The plant cell wall is composed of cellulose fibers embedded in a matrix of other complex polysaccharides and proteins – – – – – Holds cells together in tissues Contributes to physical properties of tissue Helps filter material passing between tissues Helps orient cell movements Plays a role in chemical signaling • Epithelial cells, which line the human body cavities, have a basement membrane of extracellular material called the basal lamina Plant Cell – Provides a rigid structure for the plasma membrane under turgor pressure, giving important support – Acts barrier to many fungi, bacteria, and other organisms Other Organelles • Vacuoles, found in plants and protists, are filled with an aqueous solution and are used to store wastes and pigments • Vacuoles may develop turgor pressure, a swelling that helps the plant cell maintain support and rigidity resist change of shape vacuoles- storage structure pigments(reproduction) Digestion poison 14 Prokaryotic Cells • Have a plasma membrane • Contain a region called the nucleoid where the DNA is concentrated • The cytoplasm (the plasma-membrane enclosed region) consists of the nucleoid, ribosomes, and a liquid portion called the cytosol Prokaryotic Cells Prokaryotic Cells • May have a cell wall just outside the plasma membrane • May have another membrane outside the cell wall, a polysaccharide-rich phospholipid membrane • May have a capsule – outermost slimy layer made of polysaccharides Flagella • Some bacteria, including cyanobacteria, can carry on photosynthesis. The plasma membrane is infolded and has chlorophyll • May have flagella, locomotory structures shaped like a corkscrew 15 Pili • May have pili, threadlike structures that help bacteria adhere to one another during mating or to other cells for food and protection 16 ...
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