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

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

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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
Q

Which types of chemical disinfectants disrupt the plasma membrane? (5)

A
  • Phenol
  • Biguanides
  • Iodine
  • Essential oils
  • Alcohols
26
Q

Which type of disinfectant is associated with proteins?

A
  • Inhibits protein synthesis: iodine
  • Protein denaturation: heavy metals, alcohols
27
Q

Which type of disinfectant inhibits enzyme function?

A

Chlorine

28
Q

Why is G- harder to kill than G+ bacteria? (2)

A
  • LPS binds to harmful substances to protect cell
  • Porin selectively permeable
29
Q

What are some examples of the inhibition of cell wall synthesis antibiotic mechanisms?

A
  • Vancomycin: binds D-ala-D-ala (PG crosslinks backbone)
  • B-lactam: binds PBP (crosslink formation)
30
Q

What are some examples of inhibition of protein synthesis antibiotic mechanism?

A

Aminoglycosides + macrolides disrupt peptide elongation
Tetracycline prevent tRNA binding to A site

31
Q

What are the chemical messengers of the immune system?

A

Cytokines

32
Q

what are the 4 signs of inflammation?

A

redness, heat, swelling, pain

33
Q

Three possible outcomes of complement activation

A

Increased phagocytosis
Inflammation stimulation
Lysis (cell destruction)

34
Q

What is the name of the chemical that causes fever?

A

Pyrogen

35
Q

What are the steps of phagocytosis?

A
  1. Phagocyte moves toward particle and attaches
  2. Ingestion (phagosome)
  3. Lysosomal functions forms phagolysosome
    4/5. Digestion, discharge
36
Q

Types of phagocytes (3)

A

Macrophages (from monocytes in blood), dendritic cells, neutrophils

37
Q

What do quinolones do?

A

Binds to DNA gyrase preventing supercoil relaxation
It inhibits DNA replication

38
Q

What is do rifamycin do?

A

Targets/binds RNA polymerase
Prevents transcription copying

39
Q

Examples of cell membrane disruption antibiotic mechanism

A
  • Daptomycin: plasma membrane of G+
  • Polymyxin: LPS, impacts G- outer membrane structure
40
Q

What are sulfa drugs?

A

Antimetabolites (impacts metabolism)
Binds PABA and stops folic acid synthesis

41
Q

Mechanisms to resist antimicrobial drugs (6)

A

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
Q

Antiretroviral drug categories (4)

A

a. Fusion inhibitors
b. Reverse transcriptase inhibitors
c. Integrase inhibitors
d. Protease inhibitors

Microbiology (9 decks)

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