Microbiology Exam 1
During DNA replication, which enzyme is involved in proofreading to prevent the incorrect matching of nucleotides?
DNA polymerase
RNA primers are removed from the leading and lagging strand by __________.
DNA polymerase I
In DNA replication, what is the main enzyme responsible for adding complementary nucleotides to the daughter strand while reading the parent strand?
DNA polymerase III
Which enzyme is the main contributor to the development of spontaneous mutations?
DNA polymerase III
why do endospore-forming bacteria pose challenges in healthcare settings?
Endospores are resistant to antibiotics. Endospores are resistant to heat. Endospores can survive for extended periods on surfaces.
What transport mechanisms usually involve a membrane barrier?
Facilitated diffusion Active transport Osmosis
Choose the true statement about Gram-negative versus Gram-positive cells.
Gram-negative cells are more resistant to penicillin-based drugs than Gram-positive cells.
Which of the following describes a Gram-positive cell wall?
Has a thick peptidoglycan layer
What applies to a microorganism that has a fertility plasmid?
It has a pilus. It can undergo horizontal gene transfer. It can further develop into a Hfr cell.
Acid fast bacteria
Mycobacterium and Nocardia
What is characteristic of plasmids?
Plasmids replicate independently of the cell's chromosome. Plasmids carry genes that may be involved in antibiotic resistance. Plasmids are involved in horizontal gene transfer.
Which of the following is a component of the archaeal cell wall?
Pseudopeptidoglycan
Primase lays down a short piece of __________ as a primer to start DNA replication.
RNA
What is the main enzyme required for transcription of a gene?
RNA polymerase
The role of transcription factors is to signal __________.
RNA polymerase to the promoter region of the intended gene to be transcribed
RNA viruses are able to mutate more rapidly than DNA viruses because _______________.
RNA polymerases do not have proofreading capabilities
Assume you know a cell is acid fast. Which of the following can you most safely conclude?
The organism is Gram-positive.
What viral features cause it to be classified as nonliving?
Their lack of metabolic processes Their acellular nature Their inability to replicate on their own
Why are acid-fast bacteria clinically a challenge?
These are all clinical concerns about acid-fast bacteria. They grow slowly. They have a waxy layer that limits drug entry
All of the following describe 70S ribosomes
They build proteins by linking together fatty acids. They are found in eukaryotic chloroplasts. They are found in mitochondria.
What is true about small noncoding RNAs?
They can be used to tag a ribosome to be destroyed. They are used in post-transcription regulation. They reduce the amount of protein made from mRNA.
Characteristics of Archaeal plasma membranes:
They can form monolayer membranes. The fatty acids are joined to glycerol by an ether bond. They are made of long-branched fatty acids.
Which of the following best describes the genomes of influenza, measles, Ebola, and rabies viruses?
They each have an RNA genome that is complementary to mRNA.
What is true about mycoplasma?
They normally live inside other cells. They cause "walking pneumonia." They have a sterol-enriched plasma membrane.
what is related to transposable elements?
They require the transposase enzyme. They can change the rate of gene expression. They recombine the genome.
Which of the following is mismatched?
Viruses: Replication through mitosis.
Which of the following is mismatched?
Viruses: Usually viewed with light microscopy.
Which of the following is considered a pre-transcriptional regulation and NOT a post-transcriptional regulation?
a repressed operon
In an inducible operon, what protein is used to turn off transcription by binding to the operator sequence?
a repressor protein
A transposon that relies on an RNA intermediate is called __________.
a retrotransposon
After translation, protein modifications are necessary for a final functioning product. What is part of protein modification?
addition of inorganic factors addition of organic compounds trimming
Quorum sensing allows bacteria within communities to communicate with chemical messages, which may help regulate gene expression. The chemical messages are called __________.
autoinducers
Bacteria that have a rod shape are called _________.
bacilli
Periplasmic flagella are located:
between the plasma membrane and the cell wall.
Most prokaryotic cells reproduce through _________.
binary fission
The term used by molecular biologists to describe the flow of genetic information from DNA, to RNA, to protein is __________.
central dogma of biology
Which of the following is not a viral genome arrangement?
circular RNA
If a cell is to be transformed in a lab, the cell must be __________ to uptake the available genetic information.
competent
The exchange of genetic information by use of a pilus and cell-to-cell interaction is called __________.
conjugation
During optimum conditions, E. coli will replicate every 20 minutes. Because the genes required for replication are needed as part of a routine function, these genes are considered __________.
constitutive genes
The term "redundancy" in molecular biology refers to __________.
different codons that code for the same amino acid
Prokaryotes tend to be small because they rely on _________ of nutrients.
diffusion
The viral __________ is often comprised of the host cell membrane.
envelope
In DNA replication, protein factors are more heavily required for replication in __________.
eukaryotic cells
The process of removing incorrect nucleotides and replacing them with correct ones is referred to as __________.
excision repair
Which of the following are short protein structures that help prokaryotes stick to surfaces?
fimbriae
Which of the following bacterial structures is used to propel bacteria at high speeds?
flagella
Which of the following mutations is the most detrimental to the cell?
frameshift mutation
The genetic makeup of an organism is its __________.
genotype
Which of the following is a carbohydrate substance that encourages bacterial adhesion to host tissues?
glycocalyx
The Ames test is used to identify if a chemical will result in mutations. This test uses the microorganism S. typhimurium and the amino acid __________.
histidine
The process of transferring of genetic information between cells in the same generation is referred to as __________.
horizontal gene transfer
Lophotrichous flagella are found:
in a cluster at one end pole of the cell.
Distinct collections of substances inside prokaryotic cells are known as _________.
inclusion bodies
In eukaryotic mRNA, there are sequences of mRNA that do NOT encode for specific amino acids and do NOT contribute to the protein. These sequences are called __________.
introns
Organisms from the domains Bacteria and Archaea lack:
membrane-bound organelles
What compound in a bacterial cell wall makes it acid-fast?
mycolic acid
Where is the chromosomal DNA found in prokaryotic cells?
nucleoid
What is true of osmosis?
osmosis is a passive process
Riboswitches are best defined as __________.
parts of mRNA that are not translated and act as post-transcription regulators
Which functional group is found at the 5' end of DNA?
phosphate group
The prokaryotic plasma membrane is primarily made of____________.
phospholipids
Which type of genetic material may be found in both prokaryotic and eukaryotic cells and may contain genes conferring antibiotic resistance?
plasmids
An ability to take on different shapes to enhance survival and/or ability to cause disease is called _______________.
pleomorphism
To start DNA replication, the origin of replication is recognized by a collection of factors called the __________.
primosome
One major difference between prokaryotic and eukaryotic translation is __________.
prokaryotic translation is polycistronic, and eukaryotic translation is almost always monocistronic.
__________ comprise at least half the mass of a plasma membrane.
proteins
All of the following explain why viral genomes evolve rapidly:
quick replication time of viruses. RNA viruses have a high mutation rate. reassortment events cause rapid viral evolution.
cDNA is a product of the action of __________.
reverse transcriptase
Which sugar is unique to RNA nucleotides and NOT found in DNA nucleotides?
ribose
Which of the following is not a viral genome arrangement?
segmented DNA
There are two nonstandard encoding amino acids: __________.
selenocysteine and pyrrolysine
Transduction that involves a temperate phage integrating into the host cell genome is called __________.
specialized transduction
Frequent mutations in Influenza A change the protein makeup of hemagglutinin (HA) and neuraminidase (NA) __________.
spikes
Viral __________ help viruses attach to and gain entry into host cells.
spikes
rganisms that form a cluster of sphere-shaped bacteria would be described as having a _________ arrangement.
staph
An anticodon is found on __________.
tRNA
Members of the domain Archaea are distinct from those in the domain Bacteria in that the Archaea members:
they don't cause human disease
A codon consists of __________ nucleotides.
three
UV radiation can result in __________ in a cell's DNA.
thymine dimers
The primary purpose of bacterial endospores is:
to allow certain cells to enter a dormant state.
Griffith's experiment proved that bacteria can take up naked DNA from the environment and use it as part of their genome. This process, which can occur in a laboratory or in a natural setting, is called __________.
transformation
If a bacterial cell with an intact cell wall is placed in a hypertonic solution it will____________.
undergo plasmolysis
Organisms that are adapted to survive in cold temperatures have a higher proportion of __________ in the lipid bilayer.
unsaturated fatty acids
The size of most prokaryotes is between:
0.5 and 2.0 μm.
Which of the following describes phosphotransferase systems?
It often involves group translocation through the use of phosphoenol pyruvate.
What is true about the prokaryotic cytoskeleton?
It organizes binary fission. It directs cell wall construction. It organizes biochemical processes.
Which of the following most accurately describes icosahedral viruses?
May appear spherical, but are three-dimensional polygons
If a bacterial cell with a damaged cell wall is placed in a hypotonic solution it will ___________.
absorb water from the environment and lyse.
Which type of RNA carries in amino acids and adds the amino acids to the "A" site in the ribosome?
tRNA
In DNA replication, Okazaki fragments are required in synthesizing __________.
the lagging strand, because the DNA polymerase can move only in the 5' to 3' direction
Which of the following nucleotides is found only in RNA and not in DNA?
uracil
Retroviruses produce mRNA by:
using reverse transcriptase to convert single- stranded RNA (ssRNA) to double-stranded DNA (dsDNA) and then using the dsDNA for transcription.
A __________ is a single particle made up of genetic material encased in a protein shell.
vision
Proteins provide cells with the necessary equipment to perform normal cellular activity. Without gene expression the cell __________.
would die
benefits of small size to prokaryotes
A small size allows them to inhabit diverse ecological niches. A small size allows them an increased chance for survival. A small size has the greatest surface area to volume ratio.
Which of the following describes primary active transport?
ATP is used to drive transport.
Genes can be silenced by a process called DNA methylation. Which of the following compounds is a methyl group?
CH3
All of the following spore-forming bacterial species cause disease
Clostridium perfringens. Bacillus anthracis Clostridium tetani..
Characteristics of the prokaryotic nucleoid region:
Contains RNA and proteins. It's the most likely place to find a circular chromosome in a cell. It is generally centralized in the cell.
