CH16 Flashcards

1
Q

total genetic potential of MO, code in its DNA

A

gene

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2
Q

the DNA that is expressed by the MO under a given set of conditions

A

phenotype

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3
Q

change in nucleotide sequence, may result in change of protein

A

mutation

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4
Q

types of mutations

A

mutant/wild type
spontaneous
induced

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5
Q

product of the standard “normal” allele at a locus, in contrast to that produced by a non-standard, “mutant” allele

A

wild type mutation

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6
Q

errors that lead to changes in DNA

A

spontaneous mutation

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7
Q

exposed to chemical or physical agent

A

induced mutation

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8
Q
  • damage DNA
  • alter DNA chemistry
  • interfere with repair mechanism
A

mutagen

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9
Q

point mutations can be

A

silent
missense
nonsense

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10
Q
  • AAU–>AAC
  • both code for same AA
  • protein unaltered
  • no consequence for organism
A

silent point mutation

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11
Q
  • GAG–>GUG
  • AA is different
  • significant but not always deadly
  • sickle cell anemia
A

missense point mutation

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12
Q
  • UAU–>UAA
  • stops instead of AA
  • non functional product protein fragment
A

nonsense pont mutation

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13
Q

insertion or deletion of nucleotide

A

frameshift mutations

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14
Q

describe the Ames Test

A
  • The Ames test is based on the observation that many carcinogens also are mutagens.
  • The test determines if a substance increases the rate of mutation; that is, if it is a mutagen. If the substance is a mutagen, then it is also likely to be carcinogenic if an animal is exposed to it at sufficient levels
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15
Q

what was Bruce Ames procedure for his experiment with histidine + Salmonella

A
  • had culture of Salmonella histidine auxotroph and added it to a plate with complete medium and small amount of histidine (control) and to a plate that had medium with test mutagen and small amount of histidine
  • incubated at 37 degrees C for a day or two
  • the control plate had spontaneous revertants and the other had revertants induced by the mutagen
  • if numbers are larger on mutant plate than control, then the revertants are induced by mutagen
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16
Q

why add liver enzymes to the Ames test?

A

alfotoxins (produced by fungus) are mutagenic when broken down and makes results more accurate

17
Q

exchange/combining of genetic material from two organisms

A

recombination

18
Q

recombination in eukaryotes and prokaryotes

A

-eukaryotes
diploid; crossing over b/t chromosome pairs (meiosis)
-prokaryotic
transfer of pieces of DNA from a donor bacterium to recipient (another bacteria)
incorporate into recipient DNA

19
Q

mechanisms of DNA transfer

A

conjugation
transformation
transduction

20
Q

cell to cell contact, depends on presence of plasmids

A

conjugation

21
Q

recipient bacterium takes up “free-floating” DNA

A

transformation

22
Q

bacterial virus (phage) transfers DNA from donor to recipient

A

transduction

23
Q

small pieces of extra DNA

A

plasmids

24
Q

how are plasmids independent of host chromosome

A
  • can be eliminated (hi temp, starvation)
  • multiple copies
  • some can integrate with chromosome (episome)
25
Q

genes for pili sex (conjugation)

A

fertility F plasmids

26
Q

antibiotic resistance genes

A

R plasmids

27
Q

toxin genes

A

virulence plasmids

28
Q
  • genes to degrade pesticides (Sutamonas sp)

- N2 fixation (Ribosium bacteria)

A

metabolic plasmids

29
Q

Lederburg and Tatum experiment

A
  • used triple mutants
  • positive, mixture and negative strains in tubes
  • positive and negative tubes had no spontaneous generation on plates
  • mixture plate had bacteria that synthesized all 6
  • conclusion: must be genetic change in bacteria
30
Q

Davis experiment

A
  • “U tube” experiment
  • positive and negative strains were separated by a fritted glass filter
  • filter does not allow bacteria to move, avoids cross feeding, no cells pass but media and nutrients,
  • mixes back and forth from pressure/suction
  • conclusion: cells need to interact to be phototrophs
31
Q

describe F+ by F+ mating

A
  • transfer of plasmid and gene
  • F+ pillus connects to F- cell
  • conjugation bridge forms, origin of transfer pulls of a strand of DNA and nuclease binds to origin of transfer
  • F- cell translates new strand (plasmid from F+) and becomes F+, which means it can conjugate with other cells
32
Q

describe Hfr by F- mating

A
  • most DNA transferred
  • plasmid incorporated into host chromosome (Hfr)
  • pillus connects Hfr to F- by forming conjugation bridge
  • little bit of plasmid and chromosome gene transferred into cell recipient(F-)
  • donor DNA replicated by rolling circle method and transferred
  • donor remains unchanged and recipient loses plasmid; donor DNA incorporated into recipient chromosome(F-)
  • F- cell is genetically distinct from original
33
Q

Griffith’s transformation experiment

A
  • heat-killed smooth pneumococci with capsule
    • > mouse lives
  • live, virulent, smooth pneumococci, with capsule
    • > mouse dies
  • live, nonvirulent, rough, pneumococci, no capsule
    • > mouse lives

heat-killed smooth pneumococci with capsule
+
live, nonvirulent, rough, pneumococci, no capsule
=
Live, smooth, pneumococci, with capsule PLUS
live, rough, pneumococci, no capsule isolated from dead mouse

conclusion: must have picked up trait (floating DNA) to form capsule (transformation)

34
Q

one complex mRNA with numerous ribosomes attached to produce lots of proteins in short amount of time

A

polyribosome

35
Q

describe transformation with DNA (chromosome) fragments

A

-bacterial chromosome uptakes SS of DNA and either integrates by nonreciprocal recombination (stable transformation) or degradation (unsuccessful transformation)

36
Q

describe transformation with a plasmid

A

-bacterial chromosome uptakes the plasmid and doesn’t incorporate it into its DNA (stable transformation)

37
Q

describe transduction

A

-phage attaches and causes destruction of host DNA
-synthesis of viral DNA and coat proteins
-virus capsid protein synthesis and virus assembly
-lysis of cell with release of phage particles and subsequent infection of another cell
-phage recognizes and binds to new cell
causes either:
-integration of donor DNA into recipient chromosome (stable gene transfer)
-degradation (unsuccessful gene transfer)
-survival of donor DNA (abortive transduction)

38
Q

ability to pick up DNA fragments

A

competent cells