Week 4 Notes
Week 4 Notes Bio 208
Popular in Fundamentals of Cell Biology
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This 6 page Class Notes was uploaded by Kylie McLaughlin on Wednesday September 23, 2015. The Class Notes belongs to Bio 208 at Northern Illinois University taught by Dr. Ed Draper in Fall 2015. Since its upload, it has received 17 views. For similar materials see Fundamentals of Cell Biology in Biological Sciences at Northern Illinois University.
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Date Created: 09/23/15
Week 4 Chapter 5 cont a proteins is dependent on its overall Lysozyme an enzyme can kill bacteria by destroying their cell walls but only if the enzyme is in its quotnative conformationquot Protein Structure the 3 orders of structure for all proteins 1 2 and 3 structure and a 4th order for some proteins 4 structure Primary Structure order or sequence of amino acids every protein has precise chain length and a speci c amino acid at each position number of possible sequences 20quotn is the number of letters in the amino acid quotalphabetquot is the number of amino acids in the chain Secondary Structure 2 structure is due to Hbonds between portions of the peptide backbone two types of 2 structures 1 Alpha helix 2 Beta pleated sheet Tertiary Structure 3 structure is in uenced by all of the following 1 1 structure 2 2 structure 3 Interactions between Rgroups Interactions between Rorouos 1 Hbonds between polar residues within proteins and with water on the protein surface 2 Hydrophobic interactions commonly on the inside of proteins 3 lonic bonds between an acidic negative charge Rgroup and a basic positive charge Rgroup 4 Disul de bridges covalent bonds between sulfhydryl groups SH of two cysteine residuals Quaternarv Structure some functional proteins contain 2 or more polypeptides they interact with each other in the same ways as do Rgroups within a polypeptide Sickle cell disease results from the change in one amino acid out of 146 in P hemoglobin Protein Conformation a protein is only functional in its native conformation which requires normal pH temperature and salt concentration change conditions gt protein unfolds and is nonfunctional restore conditions gt protein may refold and may become active again Chaperonins help proteins fold properly newly made proteins and some unfolded proteins get unfolded with the help of chaperonins Prions are normal cellular proteins that can unfold into an abnormal con guration that causes other normal proteins to refold into the bad con guration causing large aggregations of tightly packed beta sheets to form Nucleic Acids are Composed of Nucleotides have to have phosphate group pentose sugar and nitrogenous base 1 Nitrogenous base cytosine C thymine T in DNA uracil U in RNA 2 Sugars deoxyribose in DNA ribose in RNA 3 Phosphate groups phosphodiester bonds covalently link nucleotides bonds involve the 539 phosphate of one nitrogenous base with the 3 hydroxyl of another nitrogenous base next nitrogenous base is added to the 339 end sugar phosphate backbone is repeating structure poarity 539 phosphate end and 339 hydroxyl end bases are attached to sugars any order or sequence of bases is possible DNA Double Helix two strands of DNA sugarphosphate backbones face outward bases face inward and form speci c base pairs held together by Hbonds A and T 2 H bonds C and G 3 Hbonds DNA double helix consists of complementary base pairs which are held together by Hbonds AT base pairs and CG base pairs Ex Strand 1 AAGCTAG Strand 2 TI39CGATC Polarity of DNA Strands phosphate group at 539 end hydroxyl group at the 339 end a DNA molecule has 539 to 339 polarity the 2 DNA strands in a double helix are antiparallel they point in opposite directions RNA 1 Sugar is ribose RNA instead of deoxyribose DNA 2 Uracil U replaces T and can form UA base pairs RNA also can form CG base pairs 3 RNA is usually single stranded RNA can form base pairs with DNA another RNA or itself 4 The sequence of RNA is complementary to one strand of the DNA double helix 5 Specialized types of RNA include mRNA tRNA and rRNA Chapter 6 A Tour of the Cell Cell theory a cell is the smallest and simplest unit that displays all properties of life Order Evolutionary adaptation Response to the environment Regulation and homeostasis Get and use energy metabolism Cell division growth and development Reproduction NP P PP N Cell dimensions prokaryotic ce about 110 pm eukaryotic cell about 10100 um Resolution is the minimum distance two points can be separated and still be distinguished as separate points microscopes were invented in 1590 Microscopes Parameters 1 Magnification ratio of an objects image size to its actual size After a certain point images lose clarity with additional magni cation 2 Resolution measure of clarity of an image Minimum distance between two objects at which they can be distinguished as two objects 3 Contrast difference in brightness between the light and dark areas of an image Contrast can be enhanced by staining or abeing ce components Electron microscopy have to use dead material Scan electron microscope shows cell surfaces transmission electron microscope show details of internal structures Cell fractionation yields quotfractionsquot enriched in various organelles or structures P1 nuclei cell debris P20 mitochondria chloroplasts lysosomes P80 microsomal membranes P150 ribosomes 5150 cytosol proteins amino acids ions small cells have a high surface area to volume ratio there is a lower and upper limit to cell size arge organisms are made from many small cells not a few large cells This allows ef cient transport of materials into and out of the cell ipid bilayer with embedded proteins encoses with cytoplasm interfaces with the environment controls what enters and leaves the cell good in bad out Prokarvotic Cells are structurally simple but can be physiologically complex major components are Plasma membrane permeability barrier Cytoplasm salts small molecules macromolecule subunits enzymes DNA is a nucleoid one circular chromosome Ribosomes protein synthesis Cell wall protection prevents osmotic rupture Flagella movement Pili and cap sole interaction with other cells and the environment Usually not organelles Uquot39gt quot 39 Euka ryotes protists kingdom plantae kingdom fungi kingdom animalia Animal and Plant Cells nuceus ribosome pasma membrane endopasmic reticulum gogi apparatus mitochondria Animals Onlv lysosome agellum centrioe Plant Cells Only choropast cell wall centra vacuole pasmodesmata LNucleus chromatin DNA protein inear chromosomes condensed mitosis vs decondensed interphase pair of homologous chromosomes 2 Nuclear Envelope NE doube membrane connected to RER nucear pore complexes regulate transport into and out of nucleus 3 Nucleolus rRNA transcription and ribosome assembly Ribosomes carry out protein synthesis translation sequence of NT39s in mRNA gt sequence of AA39s in a polypeptide are large and complex the large subunits has about 50 proteins and 2 rRNA39s the small subunits has about 30 proteins and 1 rRNA transating ribosomes consist of 1 large and 1 small subunit free in the cytoplasm bound to ER gt rough ER or RER the endomembrane system synthesis modi es and delivers proteins to their proper locations 1 Ribosomes associate with RER and NE proteins are made 2 Proteins are transported to gain vesicles 3 Proteins are processed in GA then transported to their proper destinations in vesicles Rough Endoplasmic Reticulum RER parallel sheets of interconnected membranes or cisternae 1 Translation always starts on free ribosomes if they remain free gt 1 cytoplasmic proteins 2 Some ribosomes attach to ER 2a luminal proteins pass through the ER 2b integral membrane proteins remain in the ER proteins maybe glycosylated this begins in the ER and is continued through the GA SER membrane tubules are interconnected with RER but no ribosomes are attached to SER Functions of SER in various types of cells 1 Lipid synth most cells 2 Steroid synth adrenal glands testes ovaries 3 Breakdown of toxins liver 4 Store ions Ca in sarcoplasmic reticulum of muscle
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