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CHAPTER 4 Functional Anatomy of Prokaryotic and Eukaryotic Cells
Stem Cells
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DNA found in multiple chromosomes Histones with DNA
PROKARYOTES Greek “prenucleus” DNA not enclosed within a membrane DNA is usually a singular circularly chromosome DNA not associated with histones Lack membrane bound organelles Cell walls contain polysaccharide peptidoglycan Divide by binary fission EUKARYOTES “true nucleus” DNA in a nucleus DNA found in multiple chromosomes Histones with DNA Membrane bound organelles Cell walls chemically simple mitosis
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Prokaryote Characteristics
0.2 to 2.0 μm in diameter and 2 to 8 μm in length Shapes: coccus, bacillus, spiral
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ARRANGEMENTS OF COCCI Diplococci (remain in pairs)
Streptococci (remain in chain) Tetra (divide in 2 planes, remain in groups of four) Sarcinae (divide in 3 planes, remain in cube) Staphylococci (divide in multiple planes, remain in grapelike clusters)
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ARRANGEMENT OF BACILLI
Diplobacilli: appear in pairs Streptobacilli: appear in chains Coccobacilli: oval, look like cocci Palisades: picket fence
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ARRANGEMENT OF SPIRILIUM
Vibrios: curved rods Spirilla: helical shape, rigid bodies Spirochetes: helical and flexible
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External Structures sticky, gelatinous polymer outside the cell wall
GLYCOCALYX (sugar coat): sticky, gelatinous polymer outside the cell wall Composed of polysaccharide, polypeptide or both If condensed, tightly packaged -capsule Bacillus anthracis and Streptococcus pneumoniae If unorganized and loosely attached, considered a slime layer Contributes to bacterial virulence “invisible” to phagocytes Important component of biofilms Help attach to various surfaces, protects, facilitates communications Dental plaque (Streptococcus mutans) Cyanobacterium Capsule in olive green
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FLAGELLA Atichous: cell without flagella
Monotrichous: a single flagellum at one pole Lophotrichous: tuft of flagella from one or both poles Amphitrichous: single flagella at both poles Peritrichous: distributed over the entire cell
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FLAGELLA MOVEMENT file:///E:/Chapter_04/A_PowerPoint/a_Lecture_Outline/flagella_arrange.html (open disk with safari)
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Fimbriae and Pili Short, straight, thin hair-like appendages FIMBRIAE
occur at poles or evenly distributed Few to several hundred / cell Adhere to surfaces forming biofilms Neisseria gonorrhoeae - mucous membranes E. coli O157 - lining of small intestine PILI Usually longer Only one or two /cell Involved in motility (twitching and gliding motility) and DNA transfer (conjugation) Electron Micrograph of E. coli Geobacter sulfurreducens
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CELL WALL FUNCTION Responsible for shape
Prevents cell from rupturing from too much water Contributes to ability of some to cause disease STRUCTURE Peptidoglycan: repeating disaccharide attached by polypeptides forming a lattice Disaccharides: N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
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Peptidoglycan in Gram-Positive Bacteria
Linked by polypeptides Figure 4.13a
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Gram-Positive Bacterial Cell Wall
Figure 4.13b
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Gram-Negative Bacterial Cell Wall
Figure 4.13c
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Gram-positive Cell Wall
Gram-negative Cell Wall Gram-positive Cell Wall Thin peptidoglycan Periplasmic space Outer membrane Lipopolysaccharide Thick peptidoglycan Figure 4.13b–c
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Internal Structures: Plasma Membrane
Phospholipid bilayer Polar head: phosphate group and glycerol that is hydrophilic Nonpolar tails: hydrophobic fatty acids Proteins Peripheral proteins: lie at inner or outer surface Catalyze chemical rxn/support Integral proteins: inside membrane pores Glycoproteins: proteins attached to carbohydrates Glycolipids: lipids attached to carbohydrates Help protect/lubricate cell Role in certain infectious diseases Internal Structures: Plasma Membrane
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Selective permeability Breakdown of nutrients and production of energy
FUNCTION Selective permeability Breakdown of nutrients and production of energy Some have pigments and enzymes involved in photosynthesis Chromatophores or thylakoids file:///E:/Chapter_04/A_PowerPoint/a_Lecture_Outline/membrane_permeability.html
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Rhodospirillum rubrum
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PLASMID RIBOSOMES NUCLEOID CYTOPLASM
Single long, continuous circular thread of double-stranded DNA Attached to plasma membrane PLASMID Circular, double-stranded DNA Replicate independently 5 to 100 genes RIBOSOMES Site of protein synthesis CYTOPLASM 80% water, proteins, carbos, lipids, inorganic ions Thick, aqueous, semitransparent
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Inclusions (reserve deposits)
Metachromatic granules store phosphates for ATP ID: stain red with blue dyes Polysaccharide Granules Glycogen (reddish brown) and starch (blue) ID: iodine Sulfur Granules Store sulfur Lipid Inclusions Fatty acid reserve D: fat-soluable dyes Carboxysomes Enzyme ribulose 1,5-diphosphate carboxylase Use in carbon dioxide fixation Gas Vacuoles Maintain buoyancy Magnetosomes Iron oxide reserve, act as magnets
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Endospores Formed when essential nutrients are depleted Gram-positive
8 hours Gram-positive Very resistant to heat, chemicals, hard to kill Can be dormant for thousands of years 75000 Elk Lake, MN Gram positive bacteria Bacillus: anthrax, food poisoning Clostridium: gangrene, tetanus, botulism Core: DNA and protein Cortex: peptidoglycan (rigid protective) Spore Coat: protein Exosporium: protective layer Endospore formation in Bacillus subtilis.
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How bacteria communicate
TED: Bonnie Bassler 18 min
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http://student. ccbcmd
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