lecture 2-08

lecture 2-08 - 1. Lecture 2 Microbial Cell Biology 2....

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1. Lecture 2 Microbial Cell Biology
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2. Reading for Today’s Lecture Microbial Cell Biology Chapter 3 Website: http://www.microbelibrary.org/microbelibrary/files/ccImages/Articlei mages/keen/Gramstainkeen.htm
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3 Microbial Cell Biology Organization Cell Surface
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3. Bacterial Cell Organization Features found in most bacteria: Internal Structures Nucleiod Bacterial Envelope Cell Wall Membrane(s) *
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4. Bacterial Cell Organization Features found in most bacteria: Internal Structures Cytoplasm composition Nucleiod Bacterial Envelope Cell wall Membrane(s) Other Features (not found in all cells) : Internal Structures Gas vessicles External Structures Capsule Flagellum, Pili Developmental Structures Endospore Stalk
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5. Composition of the cytoplasm: Prokaryotic cytoplasm: All cellular components inside the cell membrane. Components Water is the major component (~80%) Nucleoid or nuclear region Ribosomes, DNA and RNA Polymerases Macromolecules Low molecular weight compounds and ions Intracellular reserve materials or storage polymers (optional) Gas vesicles (optional)
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6. Nucleoid or Nuclear region NOT surrounded by a membrane Amorphous Body located roughly in the center of the cell Constitute ~10% of the cells’ volume Chromosome Size Example: E. coli , which is 2-3 μm in length, has a chromosome approximately 1400 μm long.
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7. Nucleoid (DNA condensation) DNA condensation required Histone-like proteins bind to the DNA The DNA is supercoiled into around 50 chromosomal domains and making it more compact. http://student.ccbcmd.edu/courses/bio141/lecguid e/unit1/prostruct/u1fig12.html
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8. Nucleoid Chromosomal DNA Most bacteria have a single circular, double-stranded, supercoiled, DNA chromosome Exceptions: Some have linear chromosomes: Streptomyces Some have multiple chromosomes: Rhodobacterium spherodes has two circular chromosome
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9. Bacterial Ribosomes Bacteria have 70S ribosomes composed on two subunits (S=Svedberg units) 50S Large subunit: 31 proteins 23S rRNA and 5S rRNA 30S Small subunit: 21 proteins 16S rRNA - sequence used for evolution studies
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10. Bacterial Envelopes Critically important structure Confers shape & protection from lysis Bacteria are classified based on their reaction in a Gram stain Gram-positive bacteria Gram-negative bacteria
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11. Gram stains
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12. Gram stain
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13. Gram stain
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14. What is the cause of this differential staining? Gram-stain animation website: The animation explains why structural differences in Gram-positive and Gram-negative bacteria are responsible for the differential staining http://www.microbelibrary.org/microbelibrary/files/ccI mages/Articleimages/keen/Gramstainkeen.htm
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15. Bacterial Envelopes Comparison of the Bacterial Envelopes of Gram- positive and Gram-negative bacteria
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16. Gram positive versus Gram
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lecture 2-08 - 1. Lecture 2 Microbial Cell Biology 2....

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