Micro Chapters 6, 7, 8

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Microbiology
Chapters 6-8
updated 9 years ago by julicarr
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1

6 Which of the following is NOT a characteristic of biofilms? antibiotic resistance; hydrogel; iron deficiency; quorum sensing

Iron defficiency

2

6 The Spectrophotometer can be used to measure ________

Turbidity

3

6 An organism that uses O2 but can grow without it:

Facultative anaerobe

4

6 Organisms that require high heat for growth are called:

Extreme halophiles

5

6 The culture media designed to suppress unwanted mirobes while encouraging desired microbes?

Selective

6

7 The removal or destruction of all forms of microbial life is called?

Sterilization

7

7 Which of these disinfectants does not act by disrupting the plasma membrane? Phenolics; phenoll Quat ammonium compounds; halogens; biguanides

Halogens

8

7 Which disenfectant would be effective against all 3 bacteria? S. aureaus; E. Coli; Pseudomonas aeruginosa

Chlorine

9

7 Which is not used to preserve food? Nisin; sodium nitrite; Potassium sorbate; Biguanides

Biguanides

10

7 In what situation is filtration the only practical way to eliminate undesireable microbes?

When heat or other methods cannot be used (ex, liquids)

11

8 E. coli is found naturally in the large intestines. Normally this is no problem, but E.coli 0157:H7 produces shiga toxin. How did E.coli get this gene from Shigella and what is this process called?

From bacteriophage, process is called transduction

12

8 In DNA replication, the newly added nucleotide is joined to the grouwing strand by

DNA polymerase

13

8 Bacteria can acquire antibiotic resistance through all of the following except...? Mutation, integration of transposons; conjugation; snRNPs; transformation

snRNPs

14

8 A group of 3 nucleotides is called?

a codon

15

8 Which is not a method of horizontal gene transfer? binary fission; conjucation; integration of transposons; transduction; transformation

binary fission

16

6 Name the 3 primary classifications of microorganisms based on preferred range of temperature and give the range for each. Which classification is most likely to be pathenogenic to humans?

Psychorophiles -10 to 20
Mesophiles 10 to 50 ****most pathenogenic****
Thermopiles 40 to 70

17

6 Halophile, extreme halophile

Organsims highly adapted to high salt concentrations. If obligate, they require nearly 30% salt.

18

6 Hyperthermophiles (aka extreme thermophiles)

Members of Archaea have optimum growth temp. of 80 deg C or higher. Sulfur is usually important in their metabolic activity

19

6 Acidophiles

acid tolerant. Ex: chemoautotrophic bacteria, found in drainage water from coal mines. Oxidizes sulfur to form sulfuric acid. Survives at pH 1

20

6 pH range at which most bacteria grow best

6.5-7.5

21

6 Optimum pH of molds and yeasts

5-6

22

6 How do salt and sugar preserve foods?

By creating a hypertonic environment unfriendly to microbes

23

6 Innoculum

What you innoculate media with

24

6 (t/f) All bacteria reproduce by binary fission

False. Some bud

25

6 What type of media grows only gram + and has a yellow halo.

Selective and differential

26

6 An enrichment culture is used to encourage growth of_____?

bacteria present in small numbers (used ofr soil or fecal samples )

27

6 Name they 6 Oxygen growth-classified bacteria, how they grow and what they look like in a deep.

Obligate aerobes-Only aerobic growth, O2 required
*Growth at top of tube
Facultative Anaerobes-Both aerobic and anaerobic
growth. Greater in presence of O2
*Growth is best where O2 is present, but
occurs throughout tube
Obligate Anaerobes-Only anaerobic/cease in
presence of O2
*Growth only at bottom of tube
Aerotolerant Anaerobes-only anaerobic growth; but
contues in presence of O2
*Growth occurs evenly through culture
Microaerophiles-Only aerobic growth; O2 required in
low concentration
*smack dab in the middle of the tube

28

6 Name an example of an obligate anearobe

The genus Clostridium (contains tetanus & botulism)

29

6 What is a reducing media used for?

Used for growth of obligate anaerobes

30

6 What are organic growth factors?

Vitamins, amino acids, purines/pyrimidines (the bases ATGC). They are essential organic compounds an organism is unable to synthesize.

31

6 Type of media that has beef part extract, agar, peptone

Complex Media (growth of chemoautotrophs organisms)

32

6 Chemoautotroph

Uses an inorganic chemical as an energy source and CO2 as a carbon source

33

6 Chemoheterotroph

Uses organic molecules as a source of carbon and energy

34

6 Enzyme that breaks H2O2 into water & O2

Catalayse

35

6 Enzyme that breaks H2O2 into water only

peroxidase

36

6 What is a singlet and why is it important?

Normal molecular O2 that has been boosted into a higher-energy state & is extremely reactive

37

6 What is a Superoxide radical and why is it important?

Highly instable anion, formed in small amounts during normal respiration, is so toxic to cellular components that ALL organisms attempting to grow in atmospheric O2 must produce enzyme superoxide dismutase (SOD)

38

6 Superoxide dismutase (SOD)

enzyme produced by ALL organisms attempting to grow in atmospheric O2. It helps to neutralize superoxide radicals

39

6 What is a buffer and what does it do?

Chemical buffers are included in growth medium to neutralize the acids and maintain proper pH. Expeptones, aa's phosphate salts

40

6 Name 3 ways to store microbes

Refrigeration-good for short term storage

Deepfreezing- pure culture into a suspending liquid and quick-frozen under -50degC. Can usually be thawed & cultured even several yrs later

Lyphilizaiton-freeze drying, quick frozen then H2O removed by high vacuum. Organisms can be revived at any time by hydration

41

8 Transposon

A small piece of DNA that can move from 1 DNA region to another

42

8 Difference between generalized transduction and Specialized transduction

Bacteriophages that transport DNA to other cells. Generalized in the lityc cycle, Specialed in the lysogenic cyle.

43

8 Plasmid

Self-replicating circular molecules of DNA, not essential for survival

44

8 R-plasma

encodes for anibiotic resistance

45

8 F-plasmid

encodes for sex pili & transfer of the plasmid

46

8 Carcinogen

A cancer causing agent

47

8 Mutagen

An agent that causes mutations. Can be chemical or radiation.

48

8 Auxotroph/Autotroph

Auxotroph-mutant microorganism w/a nutrional requirement that's absent in the parent

Autotroph-An org that uses CO2 as it's principle carbon source.

49

8 Name the different types of mutation

Point Mutation (base substitution mutation: 1 base changed

Missense Mutation: results in change in amino acid

Nonsense Mutation: results in a stop codon where it shouldnt be

Frameshift: Insertion or deltion of 1 or more nucleotide pairs. shifts 1 entire side of DNA

50

8 Operon

Made up of promotor, opperator and structural gene

51

8 Inducible

Gene always off until induced

52

8 Repressible

Gene always on until repressed

53

8 Is the lac operon inducible or repressible?

Inducible. When no lactose it is off. When there is lactose alalactose is present * binds to repressor & innactivates it so the protein to break down lactose is made

54

8 A repressor binds to?

the operator

55

8 tRNA

Free floating, has anticodon that binds to mRNA codon. Grabs proteins to translate the mRNA into a polypeptide chain.

56

8 DNA is copied by what and in which direction?

By DNA polymerase 5'->3' direction

57

8 snRNPs

Removes entrons. mRNA has exons only. Only humans have entrons

58

8 Constitutive genes

These are expressed at a fixed rate--always "on"

59

8 Photolysis

Repair mechanism, uses visible light to separate the thymine dimer caused by UV damage

60

8 Nucleotide excision repair

enzymes cut out the incorrect base & fills in gap w/new DNA

61

7 Autoclave

High heat w/high temp. Steam must touch surface. Sterylization technique

62

7 What is ethylene oxide?

a gaseous sterilant, no high temp needed

63

7 Name Physical ways to reduce/remove bacteria

Heat-moist heat kills by coagulating proteins cause by breakage of H bond; pasteurization; dry heat sterilization kills by oxidation effects

Filtration-HEPA filter, membrane filter

Low Temp-can inhibit or kill with freeze/thaw

High pressure-if applied to liquid suspension can alter protein s of carbs

Dessiccation-Viruses, TB, endospores resistant

Osmotic pressure-uses high salt/sugar. Molds are resistant

Radiation-kills. Ionizing-gamma rays/Xrays, shorter wavelength. Radicals react w/organic cell components. Non ionizing, causes bonds to form betw adjacent purimidine bases (usually T)

64

7 Name chemical microbial controls

Phenol/phenolics (lysol) injurs lipid-containing plasma membranes; Bisphenols, used for surgical & hostpital control procedures. Gram+ staph & strep very susceptible. Biguanides affect all cell membranes, especially gram+. Halogens (iodine) impairs protein synthesis

65

8 Genotype

Genes of the organism

66

8 Phenotype

Expression of the genes

67

8 Conjugation

DNA exchange through pilli

68

8 F+/-?

The DNA for mating bridge. HFR=the plasmid that encorporates into the genomve

69

8 Important Enzymes in DNA replication, expression and repair

-DNA Gyrase: relaxes supercoiling ahead of replicatoin fork
-DNA Ligase:makes covalent bonds to join DNA strands. Okazaki fragments in excision repair
-DNA Polymerase: synthesized DNA, proofreads & repairs
-Endonucleases: