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32 Cards in this Set
- Front
- Back
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What are the different types of microorganisms? |
•Bacteria
•algae •protozoa •helminthes •fungi •Viruses: Viroids, Prions |
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When did they appear on our planet? |
Bacteria-like prokaryotes: 3.5 billion years ago Eukaryotes: 2 billion years after prokaryotes |
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What is the significance of microbes? |
1.Microbes are the earliest organisms foundin the fossil record 2.They perform essential reactions in theenvironment 3.Microbes can be harnessed to work for us 4.They sometimes cause infectious diseases |
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How/when did microbiologists learn what microbes looked like, they're not spontaneous, that they can cause disease, and that we can take precautions to prevent these diseases? |
What they look like: 1684, Robert Hooke & Antonie van Leeuwenhoek That they're not spontaneous: Mid-1800's, Louis Pasteur, Redi, John Tyndall That they can cause disease: Louis Pasteur and Robert Koch, mid 1800's Prevent diseases: Aseptic technique, Joseph Lister and Ignaz Semmelewis |
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What are the limits of Koch's Postulates in modern biology? |
1. Disease always in sick, not in well individuals
2. Isolate microorganism 3. Infection with pure microbe results in disease 4. Re-isolate microorganism from infected individuals |
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What is a domain and why was it founded in taxonomy? |
highest taxonomic rank of organisms in the three-domain system of taxonomy designed by Carl Woese, an American microbiologist and biophysicist.
Three domains: Archaea, Bacteria, Eukarya |
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Why do we use visible/uv light rather than otherforms of EMR with better resolution?
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The light creates refraction, increasing the size and resolution of the specimen |
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Phase-contrast microscope |
Transformschanges in light waves passing through a specimen into differences in lightintensity
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Bright-field microscope |
Formsits image when light is transmitted through the specimen (most common)
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Dark-field microscope |
•Bright image against a dark field
•Effective for living cells thatwould be distorted by drying or heat |
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What are the main differences betweenprokaryotes and eukaryotes?
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Prokaryoteslack a nucleus and eukaryotes possess a nucleus
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Whyfocus our study on prokaryotes?
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Structurally simple, and good model for complexity |
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Describe the structures that may be foundextracellularly
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Fimbria/pili flagellum glycocalyx: capsule, slime layer |
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Comparethe cell envelope of gram positive, gram negative and acid fast bacteria.
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Gram positive: thick peptidoglycan wall Gram negative: thin peptidoglycan wall & outer membrane |
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Whatchemicals affect peptidoglycan? |
•Penicillin
•Lysozyme |
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Howare the structure and function of the cell membrane related?
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Allows what goes in and goes out of cell. |
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Describethe bacterial cytoplasm and structures that may be found in the cytoplasm.
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•Highconcentration of water
•Solubleproteins&carbohydrates present •Thesiteof nearly all chemical reactions •Feworganelles |
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Describethe following shapes of bacteria:
a. Coccus b. Bacillus c. Coccobacillus d. Spirillum e. Spirochaete f. Vibrio g. Pleomorphic |
a. Coccus- spherical
b. Bacillus- rod shaped c. Coccobacillus- rounded/spherical rods d. Spirillum- spiral e. Spirochaete- flexible spiral f. Vibrio- rounded curved rods g. Pleomorphic- variable cells |
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Describethe following arrangements of bacteria:a. Strepto
b. Staphylo c. Diplo d. Tetrads e. Sarcinae |
a. Strepto- string
b. Staphylo- clusters c. Diplo- couplets d. Tetrads- quads e. Sarcinae-small bundle |
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How are the Archae different than Monerans?
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Monera is the kingdom and the division of monera is archae. |
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Howis growth defined in bacteria?
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a. Cellnumber NOT size
b. Growthof the culture |
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Describeprokaryotic DNA
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Prokaryotes lack a nucleus, but not DNA. DNAresides in the ribosomes.
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Explain process of DNA replication |
An enzyme called DNA gyrase makes a nick in the double helix and each side separates
An enzyme called helicase unwinds the double-stranded DNA Several small proteins called single strand binding proteins (SSB) temporarily bind to each side and keep them separated An enzyme complex called DNA polymerase "walks" down the DNA strands and adds new nucleotides to each strand. The nucleotides pair with the complementary nucleotides on the existing stand (A with T, G with C). A subunit of the DNA polymerase proofreads the new DNAAn enzyme called DNA ligase seals up the fragments into one long continuous strand The new copies automatically wind up again |
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Whyis DNA replication semi-conservative?
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Because when replicating DNA, only one half ofthe strand is copied to create a complimentary strand.
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Describe the different types of RNA moleculesand where they function in the cell.
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•InProkaryotes,transcription and translation occur in the cytoplasm
•InEukaryotes: transcription takes place inthe nucleus; translation occurs in the cytoplasm |
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How does transcription occur?
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•sequenceof gene is “read”and rewritten into messenger-RNA
•DNAhelix unwinds and serves as a template•RNAPolymerase •catalyzesthe synthesis of RNA complimentary to DNA |
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How does translation occur? |
•M-RNAis translated into the amino acid chain to form protein
•m-RNAattaches to a ribosome •composedof ribosomalRNA (r-RNA) •Thesite of protein synthesis |
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How are genes regulated in prokaryotes and eukaryotes.
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Operons |
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Distinguish between spontaneous and inducedmutations.
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spontaneous: •errorsin base pairing during DNA replication that occur spontaneously •Proofreaderenzymes induced: •increasedrate of errors due to a mutagen |
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Differentiatebetween point and frameshift mutations
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point mutation: •anucleotide base substitution •mayaffect the protein frameshift mutation: an insertion or deletion of a nucleotide base may affect protein |
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How does the Ames Test evaluate mutagenesis?
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•Salmonellatyphimuriumused to test mutagens•Can’t synthesize His
•No DNA repair enzymes •Leaky cell walls •His- mutant strain grown in the absenceof histidine •Look for reversions to His+ |
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Distinguish between the horizontal genetictransfer mechanisms of Transformation, Conjugation and Transduction (generalizedand specialized).
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Transformation: donor is dead bacterium, recipient is live bacterium. Naked DNA (small amount) Conjugation: donor is live bacterium, recipient is a live bacterium. Sex pilus makes contact with recipient (large amount of DNA) Transduction: Generalized: donor is live bacterium, recipient is live bactrium, middle man= bacteriophage (virus), infects donor then transfers (small amount= possibly a gene) to recipient Specialized: starts as lysogenic phase and inserts as a prophage |
