Exam 3 review questionss Flashcards
marine viruses play an important role in what cycle
the carbon cycle
what do all viruses contain
a capsid and a genome
viroids are _____ agents that affect _____
RNA; plants
the baltimore system classifies viruses based predominantly on what feature
their means of RNA synthesis
but for a few exceptions, when a bacterial cell is infected by a bacteriophage, the viral capsid…..
remains on the outside of the host cell
some bacterial viruses can insert their genome into the chromosome of the host cell. what is the integrated genome called
prophage
the primary factor determining the life cycle of an animal virus is the form of its____
gemone
in contrast to animal viruses and bacteriophages, plant viruses infect cells by mechanisms that do not involve specific
receptors
the period of time when virions are virtually undetectable inside the infected cell is called what
the eclipse period
bacteriopage lambda binds to the ____ that is embedded in the outer membrane of E. coli.
the maltose porin
the genome of influenza virus consists of ____
negative strand segmented RNA
flu pandemics are associated with reassortment of which viral genes
hemagglutinin and neuraminidase
what are the characteristics of HIV
- it is an enveloped virus
- it uses reverse transcriptase
- it attaches to coreceptors
which virus has been used successfully in gene therapy
lentiviruses
what process is sensitive to extracellular DNases?
transformation
gene transfer from one bacterium to another by means of a bacteriophage is called _____, whereas _____ involves the transfer of DNA following cell-to cell contact
transduction; conjugation
pyrimidine dimers are caused by
UV light
error-proof repair pathways include:
-base excision repair
-photoreactivation
-nucleotide excision repair
the simplest transposable elements are
insertion sequences
phase variation of flagellar proteins in the salmonella enterica involves
DNA rearrangments
what is the phenotype of an E. coli strain with a mutation in the lac operator that prevents the lac repressor from binding? assume glucose is absent
transcription of the lac operon is very high
transcription initiation of the lac operon is enhanced when ______ interacts with RNA polymerase
cAMP receptor protein
attenuation is a common regulatory strategy used to control the transcription of operons that code for
amino acid biosynthesis
what processes are used to control sigma factors
-proteolysis
-anti-sigma factors
- anti-anti-sigma factors
the lac operon, RNA polymerase binds to the _______ which is_______ the structural genes
promoter; upstream
some repressible operons are also regulated by attenuation. what is true regarding attenuation
-occurs after translation has started
-involves synthesis of a leader peptide
-loops form in the mRNA
a mutation to resistance to two antibiotics might occur at the rate of
10E-16
____ bind(s) to the target sequence in a PCR reaction
primiers
how does RNA- polymerase make mRNA
from DNA template
how does DNA polymerase make a molecule of DNA
from a DNA template
what does transposase do
insert DNA segments into DNA
true or false: a virion may or may not have an envelope
true
true or false: the Baltimore virus classification is based on how a virus makes dsRNA
true
true or false: a lysogenic bacterium can initiate the lytic cycle
true
true or false: a phage plaque is a zone of lysis
true
true or false: in bacterial replication, DnaA-ATP recognizes multiple sites on the bacterial chromosome
false
true or false: some bacterial DNA ligases use NQAD while some use ATP
false DNA ligases use NAD
true or false: ParM filaments segregate plasmids
true
true or false: the influenza receptor is a sialic acid glycoprotein
true
true or false: the influenza virus does not need a “cap”
false it steals cap from host mRNA
true or false: if a riboswitch ligan sequesters a ribosome binding site, transcription is prevented
false translation is prevented
true or false: ppGpp synthesis results in rRNA and tRNA synthesis
false
- Gram-negative microbes are surrounded by two layers of __________, between which lies
__________.
membrane; periplasmic space and peptidoglycan
- In order to transfer, an F factor must have which of the following?
oriT and tra genes
- Interrupted mating involves breaking __________ bridges using a blender.
conjugation
- A derivative F plasmid that contains host DNA is called an:
F’ plasmid
- Agrobacterium can transfer DNA to __________ using its __________.
plants; Ti plasmid
- The transfer of F factor in E. coli from one donor cell to a __________ cell results in two
__________ cells.
recipient; donor
- The difference between generalized and specialized transduction is
that in generalized transduction, any DNA can be moved, but with specialized
transduction, only certain DNA near the phage site can be moved
- Bacteria have developed a “Halt! Who goes there?” approach to gene exchange to prevent
unrestricted incorporation of DNA into the cell. It is called __________ and __________.
restriction; modification
- Large regions of sequence homology are required when recombining DNA molecules by
__________ recombination.
general
- Ames used his reversion test with Salmonella to screen compounds for:
mutagenicity
- Which of the following forms of DNA repair is error-prone?
a. base excision d. nucleotide excision b. methyl mismatch e. photoreactivation
c. SOS repair
C
- A(n) __________ phage may integrate its genome into that of the host cell.
temperate
- .A spacer is a(n):
piece of phage DNA
- What happens to the virus protein coat when a bacterial cell is infected?
It remains on the outside of the host cell.
- When __________ interacts with RNA polymerase, it increases the rate of transcription initiation
of the lac operon.
cAMP receptor protein
- Which of the following is the favored carbon source of Escherichia coli?
glucose
- What occurs when an inducer is added to a medium containing an organism with a metabolic
pathway controlled by a repressor?
The inducer combines with the repressor and inactivates the repressor.
- Transcriptional attenuation is a common regulatory strategy used to control many operons that code
for what?
amino acid biosynthesis
- You might say that the role of a leader sequence is to: (read carefully)
determine whether transcription can proceed through the genes in the operon
- __________ RNAs bind to complementary sequences of target transcripts and may act to
prevent translation and other effects.
Antisense
- Which of the following is a second messenger that helps to regulate biofilm
production.
cdiGMP
- Which of the following pairs is mismatched?
A) DNA polymerase — makes a molecule of DNA from a DNA template
B) RNA polymerase — makes a molecule of RNA from an RNA template
C) DNA ligase — joins segments of DNA
D) transposase — insertion of DNA segments into DNA
E) DNA gyrase — coils and twists DNA
B
- Which of the following places the steps in the PCR procedure in the correct order?
1) Incubate at 94°C to denature DNA strands;
2) Incubate at 72°C for DNA synthesis;
3) Incubate at 60°C for primer hybridization.
A) 1, 2, 3
B) 3, 2, 1
C) 1, 3, 2
D) 2; 1; 3
E) 3; 1; 2
C
- what is pBR322
a plasmid vector
- taq dna polymerase is
heat stable
- primers are how many base pairs
20 base pairs
- EcoR1 is a
restriction enzyme
- what is used to make cDNA
reverse transcriptase
- what covalently closes the plasmid vector after cutting and insertion of the “foreign” gene.
DNA ligase
- The Ames test utilizes bacterial strains of what genus?______________
Salmonella
50-51. Mutagenicity is rated based upon the number of
reversions to the prototroph
- The Ames test strains are deficient in ______________repair
DNA
- The Ames test strains are _________________auxotrophs.
Histidine
54-55. In Figure (above), which colonies are streptomycin-resistant and leucine- Requiring?
In Table (above), what will be the result of conjugation between cultures 1 and 2?
1) 4 and 8
2) 1 will remain the same;
2 will become F+, leu+, his+
- originate MAR plasmids _________
Transposition
- Electroporation_________
transformation (natural or artificial)
- Hfr (donor) ___________
Conjugation
- spread of MAR plasmids __________
Conjugation
- lysogeny __________
transduction
- Calcium heat-shock _________
transformation (natural or artificial)
- sex pilus _________
Conjugation
- generalized or specialized ___________
transduction
- cell-free DNA ___________
transformation (natural or artificial)
- In the figure above, the bacteria transformed with the recombinant plasmid and on then plated on media containing ampicillin and X-gal will
form white, ampicillin-resistant colonies.
- true or false Bacteria are protected from their own restriction certain bases in the target sequence.
true
- “rho” is a …….
bacterial transcription terminator protein
