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Micro Exam 3 > Microbial Genetics > Flashcards

Microbial Genetics Flashcards

0
Q

What does adenine pair with?

A

Thymine (A-T)

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1
Q

What 4 nucleotides compose DNA?

A

Adenine, thymine, guanine, cytosine

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2
Q

What does guanine pair with?

A

Cytosine (G-C)

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3
Q

How many nucleotides are on a single strand? And what do they code for?

A

A set of 3 nucleotides on one strand

Encodes for specific AA.

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4
Q

Where does DNA replication begin?

A

At a specific nucleotide sequence called a replication origin.

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5
Q

Where does synthesis occur, and what does it use?

A

On both strands using a variety of enzymes and proteins

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6
Q

DNA replication is semi ______?

A

Conservative

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7
Q

Which direction does replication proceed in?

A

5’ to 3’ direction on DNA strand.

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8
Q

What is the leading strand?

A

The single strand that is synthesized continuously during DNA replication.

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9
Q

What is the lagging strand?

A

The strand that is synthesized discontinuously in pieces during DNA replication.

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10
Q

What are the “pieces” on the lagging strand called?

A

Okazaki fragments.

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11
Q

Where does information from DNA pass to during gene expression?

A

To an RNA copy of the gene

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12
Q

What does the RNA copy direct?

A

The sequential assembly of a chain of AAs.

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13
Q

What is the path of the central dogma?

A

DNA —> (transcription)—> RNA —> (translation)—> protein

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14
Q

What are the 3 steps in transcription?

A

1) mRNA (messenger) is synthesized from DNA template by RNA polymerase
2) RNA nucleotides are adenine, uracil, guanine, cytosine
3) the newly created mRNA is immediately moved to ribosomes for translation.

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15
Q

What is translation?

A

Process of synthesizing proteins that occurs simultaneously with transcription.

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16
Q

Where does translation occur?

A

On ribosomes

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17
Q

How are the AAs assembled in translation?

A

Into growing polypeptide chain (when folded = protein)

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18
Q

How many genes are encoded on a single RNA in bacteria?

A

Bacteria frequently have more than one gene encoded on a single RNA using only one promotor

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19
Q

What controls transcription of genes?

A

Often controlled by means of a regulatory region, acts as an on/off switch.

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20
Q

Where is the regulatory region located?

A

Near the promotor, which is where a regulatory protein can bind.

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21
Q

What is the term for the following definition?: a set of adjacent genes coordinately controlled by a regulatory protein and transcribed as a single RNA message.

A

Operon

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22
Q

Operons are ______ or _______

A

Inducible or repressible

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23
Q

What does an inducible operon require?

A

And inducer to prevent a repressor protein from binding to the operator.

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24
Q

What does the repressible operon require?

A

That the operator be bound by a repressor

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25
Q

What is the term for the following description? End product inhibit enzymes early in pathway preventing production of the end product

A

Feedback inhibition

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26
Q

Where do spontaneous mutations occur?

A

In the natural environment

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27
Q

What is the term if only one base is changed?

A

Point mutation

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28
Q

Define missense mutation

A

Substitution of different AA in protein

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29
Q

What type of mutation occurs If change creates stop codon instead of normal AA coding codon?

A

Nonsense mutation

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30
Q

What does a removal or addition of nucleotides lead to?

A

Change in the way the DNA sequence is read - changes the codon frame or reading frame –> frame shift

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31
Q

What are transposons, and what are the AKA?

A

Segments of DNA that can move spontaneously from one site to another in the same or different DNA molecule.
Aka - jumping genes

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32
Q

What is an induced mutation?

A

A change in DNA sequence that is the result of a mutagen such ad radiation or chemical agents

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33
Q

What do chemical mutagens do to DNA?

A

Alters the binding of the DNA molecule.

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34
Q

What are 3 kinds of chemical mutagens?

A

Alkylation agents
Base analogs
Intercalating agents

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35
Q

What 2 types of radiation cause mutations?

A

UV

X-ray

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36
Q

What does uv light cause?

A

Thymine dimers

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37
Q

What does X-ray radiation cause to happen to DNA ?

A

Causes single and double stranded breaks in DNA

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38
Q

How are mutations repaired?

A

Bacteria may employ mismatch (or excision repair) as well as SOS repair.

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39
Q

What is mutant selection?

A

In order to study the function of various genes investigators induce mutations and select specific types of mutants to help understand the normal gene function.

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40
Q

What are two types of nutritional mutants?

A

Prototroph

Auxotrophs

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41
Q

Cells that grow without added growth factors (natural strains) are called what?

A

Prototrophs

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42
Q

What are cells that grow only with growth factors added in the lab called?

A

Auxotrophs

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43
Q

What are conditional lethal mutants?

A

Mutants defective for the synthesis of an essential macromolecule under specific conditions.

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44
Q

Who first demonstrated transformation?

A

Griffith.

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45
Q

What did Griffith recognize?

A

Some unknown compound was transforming bacterial cells (later identified as DNA)

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46
Q

What happens as cells die and burst?

A

DNA is released

*dna is not contained in a cell, it is “naked” *

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47
Q

What does a competent cell mean?

A

Recipient cell is able to take up DNA.

mechanism of competence is poorly understood, many populations are naturally competent during log phase of growth

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48
Q

How can competence be induced in any cell?

A

By treatment with CaCl2. Or by subjecting cells to an electrical current, called electroporation.

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49
Q

What does conjugation require contact between?

A

The two bacterial cells.

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50
Q

What two ways can DNA be transferred during conjugation?

A

1) plasmid DNA

2) chromosomal DNA

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51
Q

Which plasmid is transferred in plasmid DNA transfer?

A

The F plasmid (fertility plasmid)

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52
Q

What is the donor cell called in plasmid DNA transfer?

A

The donor cell containing the F plasmid is called F+ or male.

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53
Q

What is the recipient cell in plasmid DNA transfer called?

A

F- or female.

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54
Q

What does the F plasmid series of genes code for?

A

Formation of a sex pilus

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55
Q

When can the F plasmid transfer chromosomal DNA?

A

If the F first integrates into the chromosome then excises, bringing a portion of chromosome (F’ cell)

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56
Q

What is an Hfr cell?

A

A cell with a F plasmid that has integrated into the chromosome.

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57
Q

What must the Hfr cell do in order to transfer DNA?

A

Excise the F plasmid. The excised plasmid is termed F’ (F prime)

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58
Q

What is transduction?

A

Transfer of dna from cell to cell via a bacteriophage.

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59
Q

What two ways do bacteriophages interact with cells?

A

Lytic

Lysogenic

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60
Q

What happens during lytic interaction? (Long answer, sorry)

A
  • phage (virus) overtakes cell
  • assembly of new phage, and bacterial chromosomal DNA may be incorporated
  • cell lyses to expel new phages containing bacterial DNA - phage is capable of transduction
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61
Q

What happens during lysogenic interactions?

A
  • phage DNA integrates into host DNA. (Temperate phase)
  • phage DNA remains in cell for few to many generations
  • eventually becomes lytic
  • if a viral gene is permanently incorporated into bacterial DNA called lysogenic conversion
  • results in new bacterial strain.
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62
Q

What are the two types of transduction?

A

Generalized and specialized.

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63
Q

What is packaged during generalized transduction?

A

During production soe. Phages accidentally package only bacterial chromosomal DNA and not viral DNA in capsid.

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64
Q

What does the phage do during generalized transduction after packaging is completed?

A

This phage can still infect cells, but injects bacterial chromosomal DNA into host

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65
Q

What does the phage package during specialized transduction?

A

Both viral DNA and bacterial chromosomal DNA

66
Q

Where does the phage of specialized transduction find the chromosomal DNA ?

A

Near where viral DNA integrated during lysogenic phase.

67
Q

What was the beginning of the era of recombinant DNA technology?

A

The discovery of restriction endonucleases in bacteria.

68
Q

Why are all the cells of E. Coli called a DNA library?

A

Because each cell contains a portion of the total genome of the organism.

69
Q

What are the applications of genetic engineering for biotechnology?

A

1) stimulate bacterial cells to produce protein products not normally produced.
2) insulin is now mass produced in E. Coli (so it HGH, IFN, f.8)
3) produce subunit vaccines
4) replacement therapy)

70
Q

What is a subunit vaccine composed of?

A

Purified antigenic determinant that is separated from the disease causing organism

71
Q

What is substituted in replacement therapy?

A

Less virulent microbes for virulent strains.

72
Q

What is the term for a result of treatment in a hospital or hospital-like setting, but secondary to the patients original condition.

A

Nosocomial infection

73
Q

What does iatrogenic infection mean?

A

“Brought forth by a healer”. Used to refer illness caused by or resulting from medical treatment.

74
Q

What are 4 sources if iatrogenic/nosocomial infections?

A
  • direct contact by touching
  • contaminated fomites
  • contact with contaminate fluids
  • airborne transmission.
75
Q

What are a few ways to prevent and control iatrogenic and nosocomial infections?

A

Disinfection/ antiseptic
Hand washing
Monitoring patient population

76
Q

Define sterilization

A

Absence of all life

77
Q

Define disinfection

A

Killing/removing pathogens

78
Q

Define antiseptic

A

Disinfectant applied to tissue

79
Q

What is a substance that kills/removes only bacteria?

A

Bactericide

80
Q

What is a severe infection leading to a systemic immune response?

81
Q

Define asepsis

A

Using aseptic technique

82
Q

Define microbiostasis

A

Inhibition of microbe growth

83
Q

What is a range of activity against microbes know as?

84
Q

Define activity

A

Drugs tested to determine the lowest concentration that inhibits microbe called MIC (minimum inhibitory concentration)

85
Q

What is combination therapy?

A

Use of more than one antibiotic to increase spectrum or killing effect

86
Q

What is “increased killing effect by using multiple antibiotics” ?

87
Q

What is antagonism?

A

1 antibiotic interferes with the action of another

88
Q

What are three methods of sterilization?

A 
Moist heat (steam, boiling water)
Autoclave (steam with pressure)
Dry heat (yflame, oven)
89
Q

What are 5 kinds of antibiotics?

A
  • inhibitors of cell wall synthesis
  • inhibitors of cell membrane
  • inhibitors of protein synthesis
  • inhibitors of nucleic acid synthesis
  • antimetabolites
90
Q

What do inhibitors of cell wall synthesis prevent?

A

Cross-linking of peptidoglycan by binding to enzyme receptor sites

91
Q

What are 5 kinds of inhibitors of cell wall synthesis antibiotics?

A
  • penicillins and derivatives
  • cephalosporin
  • bacitracin
  • vancomycin
  • isoniazid
92
Q

Describe the characteristics of penicillins

A

Beta-lactam chemical structure

93
Q

Which kind of bacteria are resistant to penicillin?

A

Bacteria that produce enzyme beta-lactamase

94
Q

What structure do cephalosporins have?

A

Beta-lactam chemical structure

95
Q

How are derivative of cephalosporin grouped?

A

Into generations by their antimicrobial properties

96
Q

Which bacteria are resistant to cephalosporin?

A

Bacteria that produce enzyme beta-lactamase

97
Q

What is the first step in DNA replication?

A

Opening the DNA helix

98
Q

What is the 2nd step in DNA replication?

A

Building primers

99
Q

What is the 3rd step in DNA replication?

A

Assembly of complementary strands (A-T, G-C)

100
Q

What is the 4th step in DNA replication?

A

Remove primers and join Okazaki fragments.

101
Q

what is bacitracin toxic to? and how is it used?

A

toxic to kidneys

used topically only

102
Q

what does vancomycin fight?

A

initially staphylococcus aureus

treats systemic infections

103
Q

what is vancomycin toxic to and what is the result?

A

damage to kidneys
nerve deafness
skin rashes
thrombophlebitis

104
Q

What does isoniazid inhibit?

A

synthesis of mycolic acids in cell walls of myobacteria

105
Q

What is isoniazid active against?

A

myobacteria only

106
Q

Which antibiotic is an inhibitor of cell membrane?

A

polymyxin B and E

107
Q

What does polymyxin B and E replace?

A

replaces Mg2+ and Ca2+ from membrane lipids disrupting the structure of the bacterial cell membrane

108
Q

How is Polymyxin used?

A

only topical use. it is quite toxic

109
Q

What are 4 kinds of inhibitors of protein synthesis antibiotics?

A

Streptomycin
Tetracycline
Chloramphenicol
Erythromycin

110
Q

Are all inhibitor of protein synthesis antibiotics broad spectrum?

111
Q

Which inhibitor of protein synthesis antibiotics are bacteriostatic?

A

Tetracycline
Chloramphenicol
Erythromycin

112
Q

When is streptomycin used?

A

in conjunction with penicillin-related antibiotics in streptococcal infections for their synergistic effects

113
Q

What are two derivatives of streptomycin?

A

kanamycin

gentamycin

114
Q

What can tetracycline cause?

A

photosensitivity, renal toxicity, and stains teeth particularly in young children

115
Q

What can chloramphenicol cause?

A

toxic, can cause aplastic anemia

116
Q

Who is erythromycin typically given to?

A

people allergic to penicillin

117
Q

Is erythromycin toxic?

118
Q

What are two inhibitor of nucleic acid synthesis antibiotics?

A

Rifampin

Quinolones (fluoroquinolones)

119
Q

What is rifampin used to treat, and is it toxic?

A

treats TB in combination with other antibiotics

NOT toxic

120
Q

What do quinolones inhibit?

A

DNA replication, bacteriocidal

121
Q

What is a common example of quinolones?

A

Ciproflaxin

122
Q

What kind of antibiotic is sulfonamides (sulfa drugs)?

A

antimetabolite

123
Q

What are sulfa drugs a precursor to?

A

antibiotics, antimicrobial agents derived from sulfonic acid

124
Q

What do sulfa drugs inhibit?

A

folic acid synthesis

125
Q

Are sulfa drugs bacteriostatic?

126
Q

Are sulfa drugs wide spectrum?

127
Q

What kind of infections do sulfa drugs fight?

A

protozoa infections

128
Q

What is an example of sulfa drugs and what does this one treat?

A

Dapsone

treats myobacterium leprae (leprosy)

129
Q

What are 5 clinical problems associated with antibiotic use?

A
  • infection continues even if symptoms subside
  • affects normal flora
  • microbes become resistant
  • toxicity, not often seen, but possible
  • sensitization, develop rashes, fever, anaphylaxis
130
Q

What is penicillin a derivative of?

131
Q

What does penicillin cause enzymes in cell to do?

132
Q

What kind of infections is penicillin used for?

A

G+ bacterial infections

133
Q

Is penicillin broad spectrum?

134
Q

Are any forms of penicillin broad spectrum?

A

Yes - ampicillin works on G+ and G-

135
Q

What is bacitracin developed from?

136
Q

What does bacitracin interfere with?

A

Peptidoglycan wall assembly

137
Q

Is bacitracin effective against G- or G+?

A

Primarily G+

138
Q

What is vancomycin developed from?

A

Streptomyces

139
Q

What does vancomycin interfere with?

A

Lipid/peptidoglycan building

140
Q

What was vancomycin initially used to treat? And primarily?

A

Staph aureus

Systemic infections/heart valve infections

141
Q

What is isoniazid active against only?

A

M. Tuberculosis

142
Q

Is isoniazid bactericidal?

143
Q

Is isoniazid bacteriostatic?

A

Yes, if mycobacterium is slow growing

144
Q

What is isoniazid toxic to?

A

Liver

Peripheral nerves

145
Q

What type of antibiotic is polymyxin B and E?

A

Cell membrane disrupters

Cationic detergent

146
Q

What is the general structure of polymyxin B and E?

A

Cyclic peptide with long hydrophobic tail

147
Q

What is polymyxin most effective against?

148
Q

Is polymyxin toxic?

A

Yes. Highly neurotoxic and nephrotixic

Very poorly absorbed by GI

149
Q

What was the first antibiotic remedy for TB?

A

Streptomycin

150
Q

Which class of drugs is streptomycin in?

A

Aminoglycosides

151
Q

What kind to antibiotic is spectinomycin?

A

Protein synthesis

152
Q

Is spectinomycin broad spectrum? Is it bacteriostatic?

153
Q

Which antibiotic is spectinomycin similar to?

A

Chloramphenicol but less toxic

154
Q

What is spectinomycin used to treat?

A

Pencilling resistant gonorrhea

155
Q

What does rifampin bind to?

A

RNA polymerase inhibiting transcription

156
Q

What is quinolones active against?

A

Mainly G- , used to treat pseudomonas infections

157
Q

What is a side effect of quinolones?

A

Mild GI upset.

158
Q

Are sulfonamides wide spectrum? Bacteriostatic?

159
Q

What kind of antibiotic is trimethoprim/nitrofurantoin?

A

Antimetabolites

160
Q

What does trimethoprim/nitrofurantoin inhibit?

A

Folic acid synthesis

161
Q

Are trimethoprim/nitrofurantoin broad spectrum? Bacteriostatic?

162
Q

What does trimethoprim/nitrofurantoin treat?

A

Used in prophylaxis and treatment of uti (cystitis)

Micro Exam 3 (7 decks)

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