Exam 3 Review Flashcards
Which is not true regarding the cardinal range of bacteria?
A. the optimal temperature is closer to the minimum
B. the minimum temperature is the lowest temperature that allows proper membrane function
C. the maximum temperature is the highest temperature allowable before key enzymes begin to denature
D. all of the above are true
E. None of the above are true
A
Bacteria living in psychrophilic conditions would exhibit which of the following characteristics?
A. the presence of long fatty acid chains within the membrane
B. a dominance of polar bonds within proteins
C. significant beta sheet structures within the secondary structure of proteins
D. the presence of di-inositol phosphate
E. all of the above would be exhibited in a psychrophile
F. none of the above would be exhibited in a psychrophile
B
Which is not true of plasmids?
A. they are usually circular
B. they can replicate independently of the chromosome
C. they can be present in different copy numbers
D. their typical size is about 1/5 the size of an average bacterial chromosome
E. all of the above are true
D. none of the above are true
D
Which of the following is not true of bacterial replication?
A. replication is bi-directional from the replication fork
B. to maintain short generation times, multiple origins of replication are present
C. the next round of replication can occur before the previous round has been completed
D. there is both a lagging and leading strand
E. all of the above are true
F. none of the above are true
B
Which of the following is not a similarity between replicative DNA polymerase and the RNA polymerase used in transcription?
A. both require nucleoside triphosphates
B. both polymerize in the 5’ to 3’ direction
C. both require templates
D. both require primers to initiate new strand synthesis
E. all of above are traits of both enzymes
F. none of the above are shared traits
D
T/F: bacteria can regulate their internal temperature in an effort to stabilize themselves in different environments
False
T/F: thermophilic microorganisms tend to have unsaturated fatty acid dominating within their membranes
False
T/F: Exopolysaccharide coatings are common amongst thermophilic and hyperthermophile organisms
False
T?F: most acidophiles are categorized within the archaeal domain rather than the bacterial domain
True
T/F: Bacteria within the staphylococcus genus grow best in very low salt concentrations, but can also survive in the absence of salt
False
T/F: Microaerophilic bacteria are named because they generate smaller colonies when cultured in an oxygen concentration
False
T/F: Aerotolerant anaerobes tend to express the same set of enzymes to deal with toxic oxygen by-products as aerobic environments
False
T/F: Topioisomerases are involved in both the initiation of bacterial replication and the termination of replication
True
T/F: In bacteria there tends to be one main sigma factor used for transcription but alternative factors are usually required for special circumstances
True
T/F: All 64 codons of the genetic code encode amino acids
False
T/F: 5S rRNA is found in the large ribosomal subunit of both prokaryotes and eukaryotes
True
T/F: polysomes are observed in all three domains to improve efficiency of translation
true
The majority of pathogenic microorganisms are going to be classified as ___________ based on their optimum temperature
mesophiles
The upper threshold in regard to temperature for eukaryotic organisms is going to be _____ degrees Celsius and so far, for bacteria, we have not identified any organisms above _______ degrees Celsius
60 degrees
95 degrees
What is the difference between a psychrophile and psychotolerant microorganism?
Psychrophiles live in constant cold, psychrotolerants tolerate cold
The role of cryoprotectants such as glycerol and various sugars is to:
prevent the formation of ice crystals
Why would sodium bicarbonate or potassium be added to culturing media?
To act as a buffer
Provide one mechanism that allows an acidophile to survive in a low pH environment
highly impermeable membrane
Is the following statement most likely true or false: an alkaliphile that grows in an environment of pH 10 accounts for the same increase in its internal cytoplasmic pH by expressing additional chaperone proteins. Please defend your answer
false, the internal cell pH must be 5-9 or the cell will die almost instantly
a main way to handle a _______ environment is to increase the internal concentration of a compatible solute. a compatible solute is defined as _____________________
hypertonic, molecules that dont disrupt cells metabolism
T/F the amount of compatible solute that can be maintained by a cell is genetically determined
True
Is the following statement most likely true or false: a completely fermentative bacteria living in an oxygenic environment would not produce toxic oxygen by products. Please defend your answer
True, in complete fermentation the ETC is not used so there are no side reactions that produce toxic products
In lecture, we talked about the use of _________________ broth to determine the oxygen requirements of a bacteria
thioglycollate
Provide one way thioglycollate broth limits oxygen
use of agar
Describe how a strict aerobe will grow in thioglycollate broth?
only will grow in pink, oxygen rich layer
Thioglycollate broth does not work well for identifying microorganisms that fall into the _____________ category
microaerophiles
Important to the DNA replication process is separating the two strands of the DNA chromosomes, please provide the 3 proteins within the replisome that are imperative in this
origin binding proteins, single stranded binding proteins, helicases
In bacteria, how is DNA polymerase I different in enzymatic activity from DNA polymerase III
DNA polymerase I uses 5’ to 3’ exnuclease activity
To complete the replication of a bacterial chromosome ___________ proteins bind to _________ sites that are found on the opposite side of the chromosome from the origin of replication. Ultimately, the chromosomes are separated and bind to _________ a component within the divisome
tus, ter, FtsK
Why is it necessary that the chromosome is condensed in all 3 domains in life
Because it is very large, and does not need to be exposed at all times
The ___________ region of a bacterial cell contains the chromosome that is usually condensed by __________, the most common topioisomerase in bacteria
nucleoid, DNA Gyrase
Topioisomerases are categorized into class I or class II molecules based on:
whether they nick one strand or two strands
Explain the difference in function/roles of a histone like protein in bacteria versus histones in eukaryotes
Histone-like proteins bind to DNA using their positive charge to stabilize the domains, DNA in eukaryotes will wrap around histones to condense
Provide two differences between archaeal and eukaryotic histones
both have histone folds, but archaea don’t have the N and C terminals
Archaea uses 4 clusters, while eukarya use 8
Is the following statement most likely true or false? positive supercoiling is common throughout the prokaryotic domain. Please defend your answer
False, use negative supercoiling, Hyperthermophiles are the exception using the reverse DNA gyrase
You have two students who just started working in your lab and they have been working on their culturing techniques and obtaining a standard closed batch culture curve. When comparing their standard curves, you notice that ben always ends up with a curve that has a longer lag phase than Megan’s. They are both using the same bacteria and counting method - what could explain this difference????
ben is not keeping the bacteria happy. They are depleting their resources/nutrients so his lag time will be significantly longer since the cells have to accumulate and build what they need
The direct count method requires a microscope and a ________________
hemocytometer
Explain two advantages that direct count has compared to the viable count method
easier to count
can count alive and dead cells
higher count
faster
Provide one limitation of the direct count method
dead cells can be counted skewing the counts
