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STRUCTURE AND FUNCTION OF PROKARYOTES-PART 1 DR NAZIA KHAN ASSISTANT PROFESSOR OBJECTIVES: 1. CLASSIFY AND DEFINE EUKARYOTES AND PROKARYOTES 2. DESCRIBE DIFFERENT STRUCTURES OF PROKARYOTE CELL AND THE FUNCTIONS OF EACH STRUCTURE 3. CLASSIFY BACTERIA AND BRIEFLY DISCUSS VARIOUS METHODS OF CLASSIFICATION WHAT ARE PROKARYOTES AND EUKARYOTES • BELONG TO KINGDOM PROTISTA WHICH IS DIVIDED INTO PROKARYOTES AND EUKARYOTES • DIFFERENCES BETWEEN PROKARYOTES AND EUKARYOTES examples Bacteria and alga fungi, higher plants, animals • PROKARYOTES DON’T HAVE A MEMBRANE-BOUND NUCLEUS • THREE FUNDAMENTAL CHARACTERISTICS ARE OFTEN CONSIDERED TO DISTINGUISH PROKARYOTES FROM EUKARYOTES: i. SMALL SIZE ii. ABSENCE OF A COMPLEX, ORGANELLE CONTAINING CYTOPLASM iii. ABSENCE OF A NUCLEAR MEMBRANE PROKARYOTES • PROKARYOTIC SMALLER THAN EUCARYOTIC CELLS • PROKARYOTES ARE VERY SIMPLE CELLS UNLIKE EUCARYOTIC CELLS • THE CYTOPLASM OF PROCARYOTIC CELLS IS NOT FILLED WITH INTERNAL MEMBRANES. THE CYTOPLASM IS SURROUNDED BY A CELL MEMBRANE, A CELL WALL (USUALLY), AND SOMETIMES A CAPSULE OR SLIME LAYER • BINARY FISSION—THE SIMPLE DIVISION OF ONE CELL INTO TWO CELLS, AFTER DNA REPLICATION AND THE FORMATION OF A SEPARATING MEMBRANE AND CELL WALL. 1. THE OUTER LAYER OR CELL ENVELOPE • CELL MEMBRANE • BACTERIAL CELL WALL 2. CELLULAR APPENDAGES: • GLYCOCALYX (SLIME LAYERS AND CAPSULES) • FLAGELLA • PILI (FIMBRIAE) 3. OTHER STRUCTURES: • CYTOPLASM • CYTOPLASMIC PARTICLES (RIBOSOMES) • CHROMOSOME • SPORES (ENDOSPORE CELL MEMBRANE, PLASMA, CYTOPLASMIC, OR CELLULAR MEMBRANE • ENCLOSES THE CYTOPLASM OF A PROKARYOTIC CELL • IT CONSISTS OF PROTEINS AND PHOSPHOLIPIDS. • IT IS FLEXIBLE AND SO THIN THAT IT CANNOT BE SEEN WITH A COMPOUND LIGHT MICROSCOPE. FUNCTION: 1. SELECTIVELY PERMEABLE 2. MANY ENZYMES ARE ATTACHED TO THE CELL MEMBRANE, AND VARIOUS METABOLIC REACTIONS TAKE PLACE THERE. 3. HOUSING MANY SENSORY AND CHEMOTAXIS PROTEINS 4. GENERATION OF CHEMICAL ENERGY 5. CELL MOTILITY 6. MEDIATION OF CHROMOSOMAL SEGREGATION DURING REPLICATION • INWARD FOLDINGS OF THE CELL MEMBRANES— CALLED MESOSOMES—(CELLULAR RESPIRATION TAKES PLACE). CHROMOSOME • THE PROCARYOTIC CHROMOSOME IS A SINGLE, LONG, SUPERCOILED, CIRCULAR DNA MOLECULE, FUNCTION: 1. SERVES AS THE CONTROL CENTER OF THE BACTERIAL CELL. 2. CAPABLE OF DUPLICATING ITSELF, GUIDING CELL DIVISION, AND DIRECTING CELLULAR ACTIVITIES. • THE DNA-OCCUPIED SPACE WITHIN A BACTERIAL CELL IS SOMETIMES REFERRED TO AS THE BACTERIAL NUCLEOID. • SMALL, CIRCULAR MOLECULES OF DOUBLE-STRANDED DNA THAT ARE NOT PART OF THE CHROMOSOME (REFERRED TO AS EXTRACHROMOSOMAL DNA OR PLASMIDS) CYTOPLASM • IT IS SEMILIQUID • CONSISTS OF WATER, ENZYMES, DISSOLVED OXYGEN (IN SOME BACTERIA), WASTE PRODUCTS, ESSENTIAL NUTRIENTS, PROTEINS, CARBOHYDRATES, AND LIPIDS CYTOPLASMIC PARTICLES • RIBOSOMES • OFTEN OCCURRING IN CLUSTERS CALLED POLYRIBOSOMES OR POLYSOMES . • FUNCTION—THE SITES OF PROTEIN SYNTHESIS. • A 70S PROCARYOTIC RIBOSOME IS COMPOSED OF A 30S SUBUNIT AND A 50S SUBUNIT. • CYTOPLASMIC GRANULES OCCUR IN CERTAIN SPECIES OF BACTERIA. THESE MAY BE STAINED BY USING A SUITABLE STAIN, AND THEN IDENTIFIED MICROSCOPICALLY. THE GRANULES MAY CONSIST OF STARCH, LIPIDS, SULFUR, IRON, OR OTHER STORED SUBSTANCES. BACTERIAL CELL WALL • FUNCTIONS—PROVIDING RIGIDITY, STRENGTH, PROTECTION AND DEFINES THE SHAPE OF BACTERIAL CELL • COMPOSED OF PEPTIDOGLYCAN (MUREIN), CONSISTING OF MANY POLYSACCHARIDE CHAINS LINKED TOGETHER BY SMALL PEPTIDE • GRAM-POSITIVE BACTERIA( EG: STAPHYLOCOCCUS) -THICK LAYER OF PEPTIDOGLYCAN WITH TEICHOIC ACID AND LIPOTEICHOIC ACID MOLECULES. • GRAM-NEGATIVE BACTERIA(EG: E.COLI) -MUCH THINNER LAYER OF PEPTIDOGLYCAN, COVERED WITH A COMPLEX LAYER(OUTER MEMBRANE) OF LIPID MACROMOLECULES • MYCOPLASMA HAS NO CELL WALL • SOME BACTERIA LOSE THEIR ABILITY TO PRODUCE CELL WALLS, TRANSFORMING INTO TINY VARIANTS OF THE SAME SPECIES, REFERRED TO AS L-FORM OR CELL WALL DEFICIENT (CWD) BACTERIA. • SOME CWD BACTERIA ARE RESPONSIBLE FOR CHRONIC DISEASES SUCH AS LYME DISEASE, RHEUMATOID ARTHRITIS, AND SARCOIDOSIS. GLYCOCALYX (SLIME LAYERS AND CAPSULES • GLYCOCALYX LOCATED OUTSIDE THEIR CELL WALL. • SLIME LAYER, IS NOT HIGHLY ORGANIZED AND IS NOT FIRMLY ATTACHED TO THE CELL WALL. EXAMPLE: PSEUDOMONAS PRODUCE A SLIME LAYER • THE OTHER TYPE OF GLYCOCALYX, CALLED A CAPSULE( USUALLY A POLYSACCHARIDE), IS HIGHLY ORGANIZED AND FIRMLY ATTACHED TO THE CELL WALL. • EX; HAEMOPHILUS INFLUENZAE, KLEBSIELLA PNEUMONIAE, NEISSERIA MENINGITIDIS, AND STREPTOCOCCUS PNEUMONIAE. • NEGATIVE STAIN/INDIA INK STAINING:. OR . ANTIGEN–ANTIBODY TESTS ENCAPSULATED BACTERIA -SMOOTH, MUCOID, AND GLISTENING COLONIES; THEY ARE REFERRED TO AS SCOLONIES. NONENCAPSULATED BACTERIA TEND TO GROW AS DRY, ROUGH COLONIES, CALLED R-COLONIES. • FUNCTIONS OF CAPSULE 1. VIRULENCE FACTOR 2. PROTECTION OF THE CELL WALL 3. IDENTIFICATION AND TYPING OF BACTERIA MOTILITY ORGANELLES(FLAGELLA) FLAGELLA (SING. FLAGELLUM) ARE THREADLIKE, PROTEIN APPENDAGES • FUNCTION: ENABLE BACTERIA TO MOVE. • FLAGELLATED BACTERIA -MOTILE, NONFLAGELLATED BACTERIA -NONMOTILE. • 10 TO 20 NM THICK; CANT BE SEEN WITH THE COMPOUND LIGHT MICROSCOPE. 1. LOPHOTRICHOUS BACTERIA: TUFT OF FLAGELLA AT ONE END , 2. AMPHITRICHOUS BACTERIA.: ONE OR MORE FLAGELLA AT EACH END 3. MONOTRICHOUS BACTERIA: A SINGLE POLAR FLAGELLUM 4. PERITRICHOUS: SURROUNDING THE CELL • A PROTEIN SUBUNIT CALLED FLAGELLIN IS PRESENT • THE FLAGELLUM IS ATTACHED TO THE BACTERIAL CELL BODY BY A COMPLEX STRUCTURE CONSISTING OF A HOOK AND A BASAL BODY. • THE HOOK IS A SHORT CURVED STRUCTURE THAT APPEARS TO ACT AS THE UNIVERSAL JOINT BETWEEN THE MOTOR IN THE BASAL STRUCTURE AND THE FLAGELLUM. • THE BASAL BODY BEARS A SET OF RINGS, ONE PAIR IN GRAM-POSITIVE BACTERIA AND TWO PAIRS IN GRAM-NEGATIVE BACTERIA. FLAGELLA CONTN…………. PILI (FIMBRIAE) • Pili (sing., pilus) or fimbriae (sing., fimbria) are hair- like structures, • most seen in Gram-negative bacteria. • Composed of polymerized protein molecules called pilin. • Thinner than flagella, rigid structure, and are not associated with motility. • Functions: There are two types of pili: 1. one type enables bacteria to adhere or attach to surfaces; 2. the other type (called a sex pilus) enables transfer of genetic material from one bacterial cell to another following attachment of the cells to each other. • PILIATED STRAINS CAUSE DISEASES LIKE URETHRITIS AND CYSTITIS, • NONPILIATED STRAINS OF THE SAME ORGANISMS ARE UNABLE TO CAUSE THESE DISEASES • GENETIC MATERIAL (USUALLY IN THE FORM OF A PLASMID) IS THEN TRANSFERRED THROUGH THE HOLLOW SEX PILUS FROM THE DONOR CELL TO THE RECIPIENT CELL—A PROCESS KNOWN AS CONJUGATION. SPORES (ENDOSPORES) • BACTERIA LIKE BACILLUS AND CLOSTRIDIUM FORM THICK-WALLED SPORES AS A MEANS OF SURVIVAL WHEN THEIR MOISTURE OR NUTRIENT SUPPLY IS LOW. • BACTERIAL SPORES ARE REFERRED TO AS ENDOSPORES, AND THE PROCESS BY WHICH THEY ARE FORMED IS CALLED SPORULATION. • SPORES ARE RESISTANT TO HEAT, COLD, DRYING, AND MOST CHEMICALS. • SPORES SURVIVE FOR MANY YEARS IN SOIL OR DUST, AND SOME ARE QUITE RESISTANT TO DISINFECTANTS AND BOILING. • GERMINATION OF A SPORE MAY BE COMPARED WITH GERMINATION OF A SEED. • SPORE FORMATION IS RELATED TO THE SURVIVAL OF THE BACTERIAL CELL, NOT TO REPRODUCTION. • ONLY ONE SPORE IS PRODUCED IN A BACTERIAL CELL AND IT GERMINATES INTO ONLY ONE VEGETATIVE BACTERIUM • USES OF SPORE: 1. IMPORTANCE IN FOOD,INDUSTRIAL AND MEDICAL MICROBIOLOGY 2. STERILIZATION CONTROL 3. RESEARCH • DEMONSTRATION OF SPORE 1. GRAM STAINING 2. MODIFIED ZEIL NEELSON STAINING CLASSIFICATION OF BACTERIA CLASSIFICATION CAN BE DEFINED AS THE ARRANGEMENT OF ORGANISMS INTO TAXONOMIC GROUPS (TAXA) ON THE BASIS OF SIMILARITIES OR RELATIONSHIPS. NOMENCLATURE IS NAMING AN ORGANISM BY INTERNATIONAL RULES ACCORDING TO ITS CHARACTERISTICS IDENTIFICATION REFERS TO THE PRACTICAL USE OF A CLASSIFICATION SCHEME: (1) TO ISOLATE AND DISTINGUISH DESIRABLE ORGANISMS FROM UNDESIRABLE ONES; (2) TO VERIFY THE AUTHENTICITY OR SPECIAL PROPERTIES OF A CULTURE; OR, IN A CLINICAL SETTING, (3) TO ISOLATE AND IDENTIFY THE CAUSATIVE AGENT OF A DISEASE CRITERIA FOR CLASSIFICATION OF BACTERIA I. MICROSCOPICALLY -CELL SHAPE ,PRESENCE OR ABSENCE OF SPECIALIZED STRUCTURES SUCH AS SPORES OR FLAGELLA. II. STAINING PROCEDURES –GRAM STAINING(GRAM POSITIVE AND GRAM NEGATIVE) III. CHARACTERISTIC PIGMENTS- IV. ON THE BASIS OF THEIR COMPLEMENT OF EXTRACELLULAR ENZYME(ZONES OF HEMOLYSIS IN AGAR MEDIUM CONTAINING RED BLOOD CELLS) V. MEASUREMENT OF THEIR SENSITIVITY TO ANTIBIOTICS PHYLOGENETIC CLASSIFICATIONS: TOWARD AN UNDERSTANDING OF EVOLUTIONARY RELATIONSHIPS AMONG BACTERIA THANK YOU SELF ASSESSMENT 1. IMPORTANCE OF GLYCOCALYX IN PROKARYOTIC CELL IS a. PROTECTION AGAINST DESICCATION, ANTIBODIES AND VIRUSES b. HELPS IN DIGESTION b. HELPS IN REPRODUCTION c. HELPS IN MOTILITY 2. THE MOST COMMONLY ENCOUNTERED BACTERIA ARE ROUGHLY SPHERICAL. THE MICROBIOLOGICAL TERM DESCRIBING THIS SHAPE IS a. COCCUS b. BACILLUS c. SPIRAL d. COMA 3. A BACILLUS BACTERIUM WITH A SINGLE FLAGELLUM AT EACH END IS DESCRIBED AS a. MONOTRICHOUS b. LOPHPOTRICHOUS c. AMPHITRICHOUS d. PERITRICHOUS 4. SHINY, STICKY COLONY OF STREPTOCOCCUS PNEUMONIAE IS LIKELY TO Be a. encapsulated and pathogenic b. .nonencapsulated and nonpathogenic c. nonencapsulated and pathogenic a. encapsulated and nonpathogenic 5. DIFFERENCES BETWEEN EUKARYOTIC AND PROKARYOTIC CELLS INCLUDE ALL OF THE FOLLOWING EXCEPT a. EUKARYOTIC CELLS HAVE MITOCHONDRIA b. PROKARYOTIC CELLS HAVE MORE COMPLEX CELL WALLS c. EUKARYOTIC CELLS HAVE CILIA AND FLAGELLA WITH COMPLEX STRUCTURE d. PROKARYOTIC CELLS HAVE NO GENETIC MATERIAL WRITE SHORT ESSAYS ON THE FOLLOWING 1. SPORES 2. FUNCTIONS OF A CAPSULE 3. CELL WALL 4. WRITE 2 EXAMPLES OF EACH GRAM POSITIVE AND GRAM NEGATIVE BACILLI AND COCCI 5. WHAT ARE THE DIFFERENT METHODS TO CLASSIFY BACTERIA DRAW DIAGRAM OF A FLAGELLA