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Microbiology

By wanbshuman Feb 28, 2013 1148 Words
Ch. 1
Prokaryotes = bacteria , archaea
Eukaryotes = Fungi, protozoa , algae (Growth:: Mitosis有絲分裂)

Bacterial cell → Bacillus(rodlike) , cocus (spherical), spiral (curved) *P.S. 有時會star-shaped or square → 出現既形式: pairs, chains, clusters cell walls of bacteria → peptidoglycan (carbohydrate & protein complex) cell walls of plant and algal cell → cellulose

Growth::Binary fission = bacteria reproduce by dividing into two equal cells bacteria 吸收nutrients from dead / living organisms/ photosynthesis / inorganic substance 佢地可以swim by moving flagella

Archaea
if 佢地有cell wall → lack peptidoglycan
Found in extreme environments
-Growth:: Binary fission
-cell wall → peptidoglycan
分3 main groups → methanogens + extreme halophiles + extreme thermophiles Methanogens → produce methane
Halophiles → live in extreme env. eg. The Dead Sea
Thermophiles → live in hot sulfurous water eg. Hot springs at Yellowstone National Park

Fungi
Cells hv a district nucleus = DNA
surrounded by special envelope(lipid membrane) = nuclear membrane unicellular(eg. yeast) / multicellular (eg. Mushrooms,molds) cell wall of true fungi →compose of chitin
最common fungi → molds(mycelia (bread & fruit) → compose of long hyphae) 吸收nourishment by absorbing sol. of organic material from environment (eg. Soil , seawater)slime molds → 擁有characteristics of both fungi & amoebas

Protozoa
-unicellular
-move by pseudopods, flagella , cilia
吸收nutrients from absorb or ingest organic compound
*Euglena → photosynthetic, use light as source and carbon dioxide as chief source to produce sugars Amebae都係move by using pseudopods

Algae
好多shapes & sexually & asexual reproductive forms. -usually unicellular
-rich in freshwater, salt water, soil, association wif plants -photosynthesis for food production & growth
-no need organic compounds
-Produce oxygen & carbohydrates for other organisms(eg. Animal)

Viruses
-so small (diff. From the aboves)
-acellular (nt cellular)
-only one type of nucleic acid (DNA/RNA)
-st encase by envelope
-reproduce by using the cellular machinery of other organisms. -parasites of other forms of life (靠其他生命生存like 寄生蟲)

Multicellular Animal Parasites
-eukaryotes
-eg. helminths(蠕蟲)

Genetics info. In a cell = genome
Chomosomes contains DNA(genes)
Genes = segment of DNA

Genotype & Phenotype
G. = inheritable info. (可繼承的)
P. = 受G.影嚮而表現出來, eg. Blood, height, iq, color of eye

Ch. 10
Three domain: eukaryotes + prokaryotes (bacteria, archaea)-Each domain shares genes wif other domains eg. Thermotoga係從an archaeon演變的 -Kingdom → Phylum → class → order → family → Genus → species *Classification is base on similarity in nucleotide sequence in rRNAProkaryotes vs Virus:::-Virus cannot survive independently.-Virus 依賴host cell

Ch. 4
After dividing, Cocci → pairs = diplococci
→ chainlike = streptococci
→ groups of four = tetrads
→ groups of eight = sarcine
→ grapelike clusters = staphylococci

Bacilli → single = single bacillus
→ pairs = diplobacilli
→ chains = streptobacilli
→ oval, like cocci = coccobacilli
Spiral → curved = vibrios
→ helical shape,rigid = spirillum
→ helical shape, flexible = spirochete

External of cell wall
-Glycocalyx (gelatinous polysaccharide & / polypetide covering) → Capsule = the substance is organized & is firmly attached to the cell wall (*protect pathogens from phagocytosis & prevent desiccation) → Slime layer = .. unorganized & only loosely attacted. → Extracellular polysaccharide

-Flagella
→ rotate to push the cell
→ +ve taxis(movement of bacterium) moves towards an attractant, -ve taxis moves away from a repellent

-Axial Filaments
→ spiral cells tht move by spirochetes
→ similar to flagella, diff. : it wrap around the cell (包住)

-Fimbriae and pili
→ help cells adhere to surfaces
→ pili are involved in DNA transfer & twiching motility

Cell wall
-prevent bacterial cells from rupturing when the water pressure inside the cell > outside the cell -maintains shape of bacterium
-serves as a pt of anchorage for flagella

Peptidoglycan
-disaccharide (NAG + NAM)+ polypeptide

Diff. Between Gram +ve & Gram-ve cell wall- -ve 有outer membrane 先到peptidoglycan 再到plasma membrane while +ve 直接pep.包住plasma membrane- -ve 既 peptidoglycan → thin- +ve contains teichoic acids while -ve dun hv- +ve produce exotoxins; -ve produce exo. +endotoxin- +ve 2 rings basal body ~ -ve 4 rings

*prokaryotic plasma membrane less rigid than eukaryotic ,, . cuz lack of sterols (except Mycoplasma (prokar.) which has sterols)

cytoplasm 係plasma membrane入面
Nucleoid = bacterial chromosome
Ribosome = protein synthesis (越high rate,越large no. of ribosome) *prokaryotic ribosome smaller & less dense (70S ribosomes); eukaryotic cells (80S)

Endospores (cells) 呢個過程叫sporogenesis
1)Spore septum begins to isolate newly replicated DNA & a small portion of cytoplasm 2)Plasma membrane starts to surround DNA,cytoplasm, & membrane isolated in step 1. 3)Spore septum surrounds isolated portion, forming forespore. 4)peptidoglycan layer forms between membranes

5)spore coat forms
6)Endospore is freed from cell.
Flagella & cilia (細胞面d毛毛)-flagella → few & long -cilia → short & numerous

Nuclear envelope係包住nucleus既membrane
Nuclear envelope 附近個d係endoplasmic reticulum(ER)

Ch.5
Metabolism: sum of the Chemical rxn;;; ATP & oxygen required catabolism = release energy , breakdown of complex organic compound;hydrolytic rxn; exergonic anabolism = require energy , building of complex organic molecules;dehydration synthesis rxn;endergonicMetabolic pathway = sequence of enzymatically catalyzed chem. rxn in a cell;;determined by enzymes = encoded by genesFactors affecting enzyme activity:1)Temp. → move faster = more energy ; best → optimal temp. cuz denaturation if too high 2)pH → optimum pH;; extreme change in pH = denaturation3)Substrate conc. → increase conc of substrate molecules = increase rate until enzyme mole. are filled = max. rate4)inhibitor

Respiration
1)Aerobic respiration → the final electron acceptor in the e- transport chain is molecular O2 2)Anaerobic respirationm → ….......is usually an inorganic substance and not O2

Fermentation→ aerobic / anaerobic→ spoilage of food(general use)→ produce alcoholic beverages / acidic dairy productsScientific definition → release energy from oxidation of organic molecules; no need oxygen and use the krebs cycle ; the final electron acceptor is an organic molecule1)Alcohol fermentation → produce ethanol + CO22)Lactic acid fermentation → produce lactic acid*homolactic fermentation produces lactic acid only heterlactic fermentation produce lactic acid & other compoundsCh.6 Microbial GrowthPhysical requirement:1)Temp. → psychrophiles(cold-loving microbes) , mesophiles(moderate temp.), thermophiles(heat-loving) ; psychrotrophs → grow at 0 or 20-30degree → food spoilage2)pH → grow best in pH 6.5-7.5; molds & yeast grow abt pH5-6 ; acidophiles grow in acidic envir.3)Osmotic pressure → hypertonic envir. = plasmolysis ; extreme / obligate halophiles = grow in high salt conc. ; facultative halophiles = no require high salt envir. But grow in salt conc. 2%Chemical requirements1)Carbon2)Nitrogen,sulfur, phosphorous3)Trace elements → find in tap water, even distilled water4)Oxygen5)Organic growth factor Culture media = any material prepared for the growth of bacteria in a lab.Culture = microbes that grow and multiply in or on a culture mediaAgar = solidifying agentObtaining pure cultures → streak plate methodPreserve microbes → by deep-freezing / freeze-dryingBacterial replication::Binary fission1)parent cell enlarges2)Duplication its chromosome3)cell wall & plasma membrane begin to constrict4)Cross-wall forms,completely separating the two DNA copies; then cells separateGeneration = time required for a cell to divideMeasurement of microbial growth::Plate counts(=用plate 去量度) → needs some times 24hrs or up ; too many colonies → inaccuracies為避免too many, → serial dilutionPour plate , spread plate(better ← avoid contact between cells & melted agar)Mutation(3types)1. Beneficial mutations2. Harmful mutations3. Silent mutationsPhysical / chemical agents = mutagensWays of bacteria acquire new genetic:1. Lysogenic Conversion2. Transduction3. Transformation4. ConjugationA plasmid can integrate into the chromosome = episomePlasmid::1. Conjugative plasmid: Carries genes for sex pili & transfer of the plasmid2. Dissimilation plasmids: Encode enzymes for catabolism of unusual compounds3. Complex transposons carry other genes

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