Past Exam Questions Flashcards
Where does peptidoglycan exist in the bacterial cell?
cell wall
Where does the phospholipid bilayer exist in a bacterial cell?
cell membrane
Where do lipopolysaccharides exist in a bacterial cell?
outer membrane
Where does the periplasm exist in a bacterial cell?
in between cell membrane and outer membrane
T/F Absolutely all functions in the cell are carried out by proteins
false
What is the basic principal of microscopy?
magnification leads to better resolution
In _____ microscopy, the light rays that are usually scattered from the object are condensed and used for visualization.
dark-field
Why do we need to coat specimens with heavy metals when using electron microscopy?
to allow the objects to absorb the electrons
Out of all microscopy types we studied, this is the only one that shows images in 3D
SEM
This component is common to both Gram negative and Gram positive bacteria
peptidoglycan
The _____ component of Gram negative bacteria is endotoxic mainly due to its _____ content.
LPS
lipid A
These are major elements required by the cell in large amounts
macronutrients
Cell membranes are ______ structures
semipermeable
You have isolated a bacterium from the rumen of a cow and wish to know how it transports the sugar “whonose” into the cell. You perform an experiment that shows that “whonose” transport dissipates the proton gradient across the membrane (that means that “whonose” transport uses the proton gradient). What is the mechanism of “whonose” transport into this cell?
coupled transport
These two types of culture media differ in whether their components are defined or not
complex and synthetic
Which structure has a thick protective coat enclosing the genome?
endospores
At the optimal growth conditions of an organism, its ____ are most functional and its _____ are intact
proteins
membranes
In these growth phases, the cell numbers do not change
lag and stationary
What is NOT a physical means to control microbes?
antiseptics
T/F Because molecules naturally flow from regions of high concentration to regions of low concentration, transport across the cell membrane is impossible against the concentration gradient
false
T/F In a eutrophic lake, nutrients are abundant
true
T/F On the ocean floor, it is common to find a psychrobarophile
true
T/F In animal guts (where conditions are usually anaerobic), we expect to find strict anaerobes, facultative anaerobes, as well as strict aerobes
false
T/F Using stains with bright field microscopy has no effect on resolution
false
T/F In the microbial world. all organisms are about the same size
false
During the phage infection cycle. what happens during the attachment stage?
phage components bind to the host cell surface receptors
During the phage infection cycle. what happens during lysogeny?
the phage integrates its genome in the host genome
During the phage infection cycle. what happens during the active replication cycle?
the phage uses the host machinery to make its own viral components
During the phage infection cycle. what happens during the genome entry phase?
the phage injects its genome inside the host cell leaving the capsid outside
During the phage infection cycle. what happens during the exit stage?
the host cell lyses and the phage progeny are released to infect new cells
What is the order of the stages in a typical virus infection cycle?
attachment
entry
replication and synthesis
assembly of virus components
exit
What do bacteriophages do during entry that differs from animal viruses?
bacteriophages “push” their genomes inside the host cells leaving the capsid outside as a ghost.
Switch from lysogeny to a lytic cycle is often triggered by host ______.
stress
What are the 4 criteria used by the ICTV for virus classifications?
viral size
capsid symmetry
genome composition
host range
T/F During lysogeny, viruses are actively directing the host cell to make their proteins
false
T/F There are some viruses that could synthesize their own proteins?
false
T/F An envelope is common to all viruses
false
What 4 forms of nucleic acids are encountered in viruses?
ssDNA
dsDNA
ssRNA
dsDNA
ss –> single stranded
ds –> double stranded
What 2 types of microscopy have a dark field?
dark-field
fluroscence
What is a main purpose of the cell membrane?
transport of molecules
Gram negative bacteria have ______ cell walls.
thin
These are trace elements required by the cell in small amounts
micronutrients
Pathogens that cause disease to human grow optimally at our body temperature. Accordingly, pathogens are most probably _________.
mesophiles
T/F Only very small molecules can pass through the cell membrane by simple diffusion through the phospholipid bilayer.
true
T/F Out of all physical means of microbial control we discussed, filtration is the only one that achieves sterilization.
false
T/F An example of a resistant form of growth that starts by attachment to surfaces is the biofilm.
true
T/F Electron microscopy can be used to resolve objects in the nanometer range.
true
When a transport move molecules along the concentration gradient, the transport is called _______ and does NOT require energy.
passive
The smallest distance by which two objects can be separated and still be distinguished:
resolution
The sudden introduction of large quantities of a previously limited nutrient in a system:
eutrophication
The time it takes for a population to double:
generation time
The apparent increase in the size of an abject
magnification
The phase of growth where stress response is tun=rned on in anticipation of lack of nutrients:
stationary phase
The phase of growth where cells are actively growing and dividing:
log phase
The phase where cells are preparing to grow:
lag phase
You see two species growing on a MacConkey agar plate. One is pink growth, one is yellow growth. Is the medium selective or differential? Does the plate contain a pure culture?
differential
no
In order to avoid any detrimental scenarios that could occur during DNA replication prior to cell division, the process of replication happens in a _________ manner where each of the daughter cells will receive a double stranded DNA where one strand is old and the other is newly made.
semi-conservative
In translation, there are 64 possible ______. ______ of them don’t code for any amino acids and are used as ______ .
codons; 3; stop codons
Why do cells need to import DNA (3)?
to use it as food
to fix a damaged genome
to adapt to new environments
T/F Gene transfer by conjugation between two unrelated cells is a form of vertical gene transfer.
false
horizontal gene transfer
T/F Gene transfer is known to occur between different cells in an environment. There is only one way for this to occur.
false
multiple ways for gene transfer to occur and between many different specimens
This type of mutation where one nucleotide is switched to another…
point
If the point mutation from T to A leads to calling the same amino acid during translation…
silent mutation
The point mutation from T to A leads to calling a different amino acid during translation…
missense
The point mutation from T to A caused a switch of the codon to a stop codon…
nonsense
Mutation where a couple of bases are added…
insertion
Mutation where a couple of bases are removed…
deletion
Insertion and/or deletion would lead to a _____ mutation in the protein product.
frameshift
From a gene to mRNA is called…
transcription
From mRNA to a protein is called…
translation
A cell can control gene expression at the level of process A (that means controlling gene expression before the mRNA product is made) by manipulating the activity and/or the amount _______ available in the cell.
sigma factor
Regulatory proteins could either be ______, that bind to the DNA and prevent process A form starting, or ______, that bind to the DNA and stimulate process A to start.
repressor
activator
A process starts with the DNA in a relaxed state (the circle) and then introduces twists (one of them is shown). Going through this process several times would produce a(an) _____ molecule. Enzymes that increase and decrease this state are known as _______.
supercoiled
topoisomerases
In the process of DNA replication for a double strand, the _____ is replicated continuously, while the ______ strand is replicated in fragments. This is because the replication enzyme can only work in one direction 5’ to 3’.
leading
lagging
What type of bond connects the phosphorus chain in DNA?
phosphodiester
In DNA structure, _____ on one strand binds to ______ on the opposite strand via _____ H-bonds.
C; G; three
What pathway produces more ATP from the breakdown of 1 glucose?
EMP
ED and EMP have this in common
they both produce 2 pyruvates from 1 glucose
Ethanol is a byproduct of _______ and ________ fermentations.
ethanolic and heterolactic
During respiration, which step(s) produce(s) NADH?
both PDC and TCA produce NADH
If the ETS is halted (i.e. stopped working) during respiration, for example, when the cell runs out of an electron acceptor, what would be the other way of recycling the NADH?
Fermentation
