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Microbiology > Exam 3 (11, 13, 14, 17) > Flashcards

Exam 3 (11, 13, 14, 17) Flashcards

1
Q

Functionally related genes are organized together in an…
(They also consist of promoter + operator sites and structural genes they control)

A

Operon

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2
Q

What is the function of helicase?

A

Unwinds strands of DNA during replication

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3
Q

What is the function of DNA gyrase?

A

Relaxes DNA supercoiling

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4
Q

Process of DNA to RNA (uses RNA polymerase)

A

Transcription

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5
Q

Type of mRNA formed during transcription in prokaryotes vs eukaryotes

A

Prokaryotes: polycistronic (no editing needed)
Eukaryotes: monocistronic (requires RNA editing)

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6
Q

What type of mutation is the substitution of one base?

A

Missense mutations (point)

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7
Q

Genes that are constantly expressed are called?

A

Constitutive

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8
Q

When tryptophan concentrations are high, is the Trp operon active?

A

Nope

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9
Q

When will the lac operon be on?

A
  • Glucose absent
  • Lactose present
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10
Q

What is the function of the repressor protein (LacI) in the lac operon?

A

Binds to operator, blocks transcription

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11
Q

Amount of mRNA translation start sites in prokaryotes vs eukaryotes

A

Prokaryotes: multiple + simultaneous transcription/translation
Eukaryotes: single site + no simultaneous synthesization (physical separation between mRNA and ribosomes, RNA editing needed)

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12
Q

What is the function of DNA ligase?

A

Joins ends of DNA fragments together

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13
Q

What are genes that are normally on but can be turned off called?

A

repressible

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14
Q

What is catabolite repression?

A

Process of turning off expression of all other operons if glucose is present

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15
Q

Trp operon (3)

A
  • Usually on (repressible)
  • Low trp = TrpI (repressor protein) is inactive, cannot bind to operator, transcription occurs!
  • High trp = trp binds to TrpI (activates it) and TrpI binds to operator, polymerase is blocked, no transcription
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16
Q

What monitors lactose and what monitors glucose?

A
  • Lactose: LacI
  • Glucose: CAP
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17
Q

Lactose concentrations + lac operon activation

A
  • Low lactose = operon inactive, LacI (repressor protein) is expressed/active, LacI binds to operator site, RNA polymerase blocked and no transcription
  • High lactose = allolactose (inducer) binds to LacI for deactivation, transcription occurs if RNA polymerase can bind
18
Q

cAMP + CAP

A

cAMP is made under nutritional stress
- Low glucose = high cAMP (cAMP binds to CAP - activation, CAP binds to promoter allowing transcription via RNA polymerase)
- High glucose = low cAMP, inactive cAMP and no binding, no transcription

19
Q

what are the different types of horizontal gene transfer? (4)

A
  • transformation: free floating DNA taken in by competent cells
  • transduction: bacteriophages – generalized: random fragments packaged instead of virus (lytic); specialized: genes near phage DNA insertion site can be transduced (lysogenic)
  • conjugation: transfer of plasmids via conjugative/sex pilus (hairlike), requires conjugative plasmid
  • transposition: DNA movement (transposon - jumping gene; transposase: enzyme aiding transfer of transposon)
20
Q

Disinfectant vs antiseptic

A
  • Disinfectants inactivate microbes on inanimate surfaces or fomite
  • Antiseptics disinfect living tissue
21
Q

Examples of temperature control methods (3)

A
  • Dry heat: incineration, hot air sterilization
  • Moist heat (moisture penetrates): pasteurization (gentle heating); boiling; autoclave (pressure raises temp of stem above boiling point)
  • Cold temperature: refrigeration/freezing (slows metabolism)
22
Q

What is dessication?

A

Removal of water e.g. freeze drying

23
Q

What is osmotic pressure?

A

High salt/sugar, reduces water like fruit cups or cured meats

24
Q

What are the types of radiation control methods?

A
  • Nonionizing: thymine dimers, doesn’t penetrate well, e.g. UV light
  • Ionizing: DNA breaks, e.g. X-rays or gamma rays
25
Which types of chemical disinfectants disrupt the plasma membrane? (5)
- Phenol - Biguanides - Iodine - Essential oils - Alcohols
26
Which type of disinfectant is associated with proteins?
- Inhibits protein synthesis: iodine - Protein denaturation: heavy metals, alcohols
27
Which type of disinfectant inhibits enzyme function?
Chlorine
28
Why is G- harder to kill than G+ bacteria? (2)
- LPS binds to harmful substances to protect cell - Porin selectively permeable
29
What are some examples of the inhibition of cell wall synthesis antibiotic mechanisms?
- Vancomycin: binds D-ala-D-ala (PG crosslinks backbone) - B-lactam: binds PBP (crosslink formation)
30
What are some examples of inhibition of protein synthesis antibiotic mechanism?
Aminoglycosides + macrolides disrupt peptide elongation Tetracycline prevent tRNA binding to A site
31
What are the chemical messengers of the immune system?
Cytokines
32
what are the 4 signs of inflammation?
redness, heat, swelling, pain
33
Three possible outcomes of complement activation
Increased phagocytosis Inflammation stimulation Lysis (cell destruction)
34
What is the name of the chemical that causes fever?
Pyrogen
35
What are the steps of phagocytosis?
1. Phagocyte moves toward particle and attaches 2. Ingestion (phagosome) 3. Lysosomal functions forms phagolysosome 4/5. Digestion, discharge
36
Types of phagocytes (3)
Macrophages (from monocytes in blood), dendritic cells, neutrophils
37
What do quinolones do?
Binds to DNA gyrase preventing supercoil relaxation It inhibits DNA replication
38
What is do rifamycin do?
Targets/binds RNA polymerase Prevents transcription copying
39
Examples of cell membrane disruption antibiotic mechanism
- Daptomycin: plasma membrane of G+ - Polymyxin: LPS, impacts G- outer membrane structure
40
What are sulfa drugs?
Antimetabolites (impacts metabolism) Binds PABA and stops folic acid synthesis
41
Mechanisms to resist antimicrobial drugs (6)
Target modification (random mutations) – mutation changes cellular target and drug can’t bind Destroy/inactivate the antibiotic – enzyme chemically changes drug blocking binding Drug efflux pump (pump drug out of cell) Block entry of antibiotic – membrane/wall is altered to reduce drug entrances Target overproduction – make excess target or make something else that allows cell functioning Target mimicry – produce something like target so antibiotic binds to that instead
42
Antiretroviral drug categories (4)
a. Fusion inhibitors b. Reverse transcriptase inhibitors c. Integrase inhibitors d. Protease inhibitors

Microbiology (9 decks)

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