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micro test 2
Terms in this set (40)
A single bacteriophage particle infects a susceptible bacterial cell. Soon a large number of new phage particles are released, and the bacterial cell is killed in the process. This type of viral reproduction is called:
Which one of the following statements about bacteriophages is correct?
Many bacteriophages have have a complex (head and tail) morphology
The _________ of a virus protects its __________
capsid; nucleic acid
During their reproductive cycle, a group of RNA animal viruses make DNA copies of their genetic material using an enzyme called reverse transcriptase. These viruses are called:
A prion is:
a protein that is infectious in the absence of nucleic acid
Zika virus is a member of the family Flaviviridae that spreads from person to person primarily by:
Which one of the following statements accurately describes bacteriophage plaques?
Each plaque in theory arises from a single virus particle
In cellular organisms, a gene is defined as:
a complete DNA sequence that specifies a functional polypeptide or RNA product
What is the outcome of an Her cell mating with an F- cell?
The F- cell acquires genetic info from the Hfr cell
The transfer of donor bacterial DNA to a recipient cell mediated by a bacteriophage is called:
During a DNA cloning procedure, a DNA restriction fragment is covalently incorporated into a self-replicating DNA carrier molecule, such as a plasmid. This DNA carrier molecule is often referred to as a:
The _________ is the complete set of genetic info that an organism possesses
Restriction endonucleases are enzymes that:
cleave DNA by making cuts only at specific base-pair sequences
Thought question: A particular gene is transferred from a donor cell to a recipient cell, resulting in detectable change in the recipient cell's phenotype. When the donor cells are completely removed from the culture medium by filtration prior to adding the recipient cells to the medium, gene transfer still occurs at the same rate as when the donor cells are present. What process of gene transfer is taking place?
It could either be transformation or transduction, depending on whether the pore size of the filter is small enough to trap bacteriophages
A strand of DNA includes the following base sequence: guanine-thymine-cytosine-adenine. If this DNA strand is used as a template for transcription, what is the corresponding base sequence of the messenger RNA molecule?
A bacterial enzyme is a single polypeptide that is 300 amino acids in length. What minimum number of nucleotides must be in the coding sequence to specify the complete amino acid sequence of this polypeptide?
How are polypeptides synthesized using the information in the genetic code?
DNA directly guides mRNA synthesis, and then mRNA directly guides polypeptide synthesis at the ribosome
The major enzyme activity that synthesizes new DNA at the replication fork in bacteria is called:
DNA polymerase III
In E. coli, the terminus of replication lies about halfway around the chromosome form the origin of its replication. This type of DNA replication is called:
Thought question: A bacterium grows in a simple mineral salts medium that contains only potassium phosphate, ammonium chloride, magnesium sulfate, and sodium chloride without the addition of any carbon. What then must be the source of this organism's carbon?
carbon dioxide in the atmosphere
If a bacterium has a minimum growth temperature at 15 degrees C, then it is considered to be a:
We can't be certain bec we don't know what its optimal growth temperature is
Aerotolerant anaerobes are microbes that:
cannot use O2 for growth but are able to grow in its presence
What practical application of the metabolism and growth of extremely acidophilic bacteria was discussed in lecture?
solubilization of metals for recovery from low-grade ores
Approx. 3% of a bacterial cell's dry weight is typically made up of phosphorus. What is an obvious reason (or reasons) why the cell needs this particular element in such a high abundance?
two or more of these answers is correct:
phosphorus-containing amino acids are incorporated into proteins
the bulk of the cell membrane is composed of phosphorus-containing lipids
Peptidoglycan is synthesized from phosphorus-containg NAG and NAM
Phosphorus-containing nucleotides are incorporated into DNA and RNA
If you have a nutrient solution with a pH of 7.0 and adjust it to a pH of 2.0 in order to grow an acidophilic bacterium, what is the total increase in the concentration of hydrogen ions?
The FtsZ protein in E. coli is essential for cell division because it:
forms a ring at mid-cell that constricts as the septum grows inward
growth phase chart
What is the segment of the growth curve labeled D called?
In which segment of the growth curve are new cells being added by cell division at a rate faster than cells are dying?
Why is the segment of the growth curve labeled A horizontal?
cells are not dividing because they are adapting to the new culture conditions
A form of cell division that is relatively common in yeasts is:
If the number of cells in an exponentially growing bacterial culture at time t is 4.0 x 10^5 cfu per ml (log = 5.6) and the culture has been growing for a total of 480 minutes, what is the generation time?
It's impossible to say since we don't know the number of cells at time t-0
Generation time refers to:
the amount of time it takes a bacterial population to double in number
How does a membrane filter remove bacteria from the liquid being filtered?
2 or more of the answers are correct:
small pore size
dehydration of cells
denaturation of enzymes
How are the plastic objects such as petri dishes usually sterilized?
treated with ethylene oxide
From the question above, how does this treatment achieve sterilization?
Ethylene oxide alkylates proteins and thereby disrupts the activities of essential enzymes
In general, what is the most effective method to kill bacterial endospores?
autoclave at 121 degrees C for 15 min or longer
From the question above, an exception must be made in using this method to kill endospores if the material being treated:
is heat sensitive
The first systematic attempt to use a chemical substance to treat an infectious disease in vivo (chemotherapy) was made by:
How does sulfanilamide (the original sulfa drug) work?
acts as a competitive inhibitor of a bacterial enzyme involved in folic acid biosynthesis
Tetracycline works against bacteria by:
inhibition of protein synthesis
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