Ex 2 Flashcards
_____ are extremely efficient
enzymes
Anabolism
enzyme regulated reaction that build complex organic molecules from simpler ones using energy and bulding blocks from catabolism - reduction
In nature, microorganisms seldom live in the isolated single-species colonies that we see on laboratory plates but they more typically live in microbial communities called _____.
Biofilms
Obligate anaerobes die in the presence of oxygen because they produce neither _____ nor catalase.
Oxydase
Enzymes
metabolic pathways are determined by enzymes - which is then determined by the cell’s genetic makeup
Which pair is NOT correct?
A) volutin - polyphosphate
B) glycogen - polysaccharide
C) Lipid inclusion - poly-β-hydroxybutyric acid (PHB)
D) Magnetosome - bacterial motility in the antarctic pole
E) Gas vacuole - buoyancy
D) Magnetosome - bacterial motility in the antarctic pole
High concentrations of salts and sugars create a hypertonic environment that causes a phenomenon called ____ in bacterial cells where water leaves out of cytoplasm separating cell membrane and cell wall.
Plasmolysis
Catabolism
enzyme- regulated reaction that releases energy and building blocks for anabolism through oxidation
How is coupling of catabolism and anabolism made possible?
Through ATP and NADPH - which stores energy derivd from the catabolic reactions and releases it later to drive the anabolic reactions
This figure shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture.
Which section illustrates a logarithmic change in cell numbers?
A) b
B) b and d
C) a
D) d
E) a and c
A) b
Which of the following is NOT a typical characteristic of most bacterial plasma membranes?
A) They contain proteins.
B) They are composed of a phospholipid bilayer.
C) They serve as the site of energy production.
D) They are permeable to charged molecules and ions.
E) They are selectively permeable.
D) They are permeable to charged molecules and ions.
collision theory
all atoms, ions, and molecules are continuously moving and colliding with one another for chemical reactions to occur
_____ can be increased by enzymes or by increasing temperature or pressure
Reaction rate
Enzymes 6 classes
- Oxidoreductase 2. Transferase 3. Hydrolase 4. Lyase 5. Isomerase 6. Ligase
What are metabolic pathways determined by?
Enzymes
This figure shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture.
Which is NOT true about the section c?
A) It is stationary phase.
B) No new cell division occurs.
C) Cells can reach this phase when no more nutients are present.
D) Cells can reach this phase when too much of waste products are present.
E) All of the above are true about the section c.
B) No new cell division occurs.
The effect of oxygen on the growth of various types of bacteria was tested in a medium shown below.
Which tube shows the expected growth pattern for a facultative anaerobe?
A) a
B) b
C) c
D) d
E) e
D) d
enzymes are _____
specific
PepG in the iron ABC transporter in E. coli is a(an) _____ protein because it penetrates the membrane completely and can be removed from the membrane only after disrupting the lipid bilayer.
A) peripheral
B) integral monotopic
C) transmembrane
D) scaffold
E) linker
C) transmembrane
10 3 cells of E. coli was inoculated in 1 ml of nutrient broth. If it took 120 min for the culture to reach 8 X 10 3 cells/ml, what is the doubling time of this E. coli strain? Assume that the culture has 20 min of lag phase.
A) 60min
B) 120min
C) 30min.
D) 10min
E) 40min
E) 40min
______ is the sum of biochemical reaction that either releases or requires energy
Metabolism
Reaction rate
the frequency of collisions with enough energy to bring about a reaction
Which is NOT produced during aerobic respiration?
A) hydrogen peroxide
B) superoxide radical
C) singlet oxygen
D) hydroxyl radical
E) All of the above can be produced during aerobic respiration.
E) All of the above can be produced during aerobic respiration.
how do you name an enzyme?
names usually end in -ase
Enzymes are subject to cellular controls by what two ways?
- control of enzyme synthesis - transcriptional, post-transcriptional and translational regulation 2. control of enzyme activity - post translational regulation.
On EMB plate, only gram-negative organisms optimally grow and E. coli shows metallic green color. Thus, EMB medium is a(n) ____.
A) differential medium.
B) selective medium.
C) enrichment medium.
D) selective and differential medium.
E) differential and enrichment medium.
D) selective and differential medium.
How are enzymes specific?
- each enzyme acts on a specific substrate, catalyzing mostly only one reaction - specificity of enzymes is made possible by their characteristic three - dimensional shape
Membrane fluidity is regulated by sterols in eukaryotes and ____ in prokaryotes. A) hopanoids B) cholesterols C) polyenes D) LPS E) phospholipids
A) hopanoids
_______ is defined as the destruction of vegetative pathogens on living tissue.
A) Disinfection
B) Antisepsis
C) Sanitization
D) Sterilization
E) Degerming
B) Antisepsis
Metabolism
the sum of the biochemical reaction - either releases or require energy
inorganic cofactors
Fe, Zn, Mg, Ca forming a bridge between enzyme and substrate
What inhibitors play a role in a kind of biochemical control called feedback inhibition or end-product inhibition?
Allosteric inhibitors and Competitive inhibitors
apoenzyme =
protein portion
Lactobacillus lactis is a(an) ____ because it grows the same with or without oxygen.
A) obligate aerobe
B) aerotolerant anaerobe
C) obligate anaerobe
D) microaerophilic aerobe
E) facultative anaerobe
B) aerotolerant anaerobe
If you want to quantify a very small number of bacteria in a water sample, you probably need to use
A) the pour plate method.
B) the filtration method.
C) a spectrophotometer.
D) a Petroff-Hauser slide.
E) the spread plate method.
B) the filtration method.
This figure shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture.
Which section shows a growth phase where cells try to adopt to a new growth condition?
A) a
B) b
C) c
D) d
E) a and d
A) a
A yeast, Saccharomyces rouxii is a(an) _____ because it can grow at high sugar concentrations causing spoilage in the sweet goods industry, with products such as fruit juice concentrates, liquid sugars, and honey.
A) xerophile
B) acidophile
C) osmophile
D) psychrophile
E) thermophile
C) osmophile
You isolated a Bacillus subtilis strain from soil that cannot grow in the medium that has glucose as the sole carbon source. You later found that the bacterium’s growth required an amino acid, lysine, in addition to glucose.
ThisBacillus subtilis is a(an) ____.
A) aminotroph
B) lithotroph
C) auxotroph
D) autotroph
E) prototroph
B) lithotroph
What enzyme regulates the reaction that releases energy and building blocks for anabolism through - oxidation
Catabolism
Halobacterium salinarum is a(an) _____ because it has adapted so well to high salt concentrations that it actually requires high osmotic pressure for growth.
Extreme halophiles = obligate halophiles
By which of the following mechanisms can a cell transport a substance against a concentration gradient?
A) facilitated diffusion
B) extracellular enzymes
C) simple diffusion
D) active transport
E) aquaporins
D) active transport
Wild-typeE. coli cells are growing in a liquid medium that contains a high concentration of phenylalanine but lack of tyrosine and tryptophan. Which of the following enzyme or enzymes are subject to the feedback inhibition by phenylalanine so that E. coli still can synthesize tyrosine and tryptophan?
1 = DAHP synthase that only responds to (feedback inhibited by) tyrosine 2 = DAHP synthase that only responds to (feedback inhibited by) phenylalanine 3 = DAHP synthase that only responds to (feedback inhibited by) tryptophan
A) 3
B) 3and6
C) 2and8
D) 1,2,3,and6
E) 2
C) 2and8
All of the following methods can measure the viable cell count EXCEPT
A) Pour plate method.
B) Spread plate method.
C) Filtration method.
D) Petroff-Hauser slide method.
E) All of the above can measure the viable cell count.
E) All of the above can measure the viable cell count.
_____ prevents the formation of functional cell wall peptidoglycan by inactivating transpeptidases. A) Bactoprenol B) Vancomycin C) Mycolic acid D) Penicillin E) Lysozyme
D) Penicillin
what factors influence activity of an enzyme?
- temperature (optimal temperature) - reduces the rate of enzyme’s denaturation 2. pH 3. Substrate concentration 4. inhibitors - competitive - compete with the substrate for the active site - non-competitive - bind to allosteric site on enzyme causing it to change shape
The effect of oxygen on the growth of various types of bacteria was tested in a medium shown below.
Which tube shows the expected growth pattern for a microaerophile?
A) a
B) b
C) c
D) d
E) e
E) e
Cofactor =
nonprotein component
Which does NOT produce endospore?
A) Bacillus subtilis
B) Bacillus anthracis
C) Clostridium difficile
D) Lactobacillus acidophilus
E) Clostridium tetani
D) Lactobacillus acidophilus
You isolated a Bacillus subtilis strain from soil that cannot grow in the medium that has glucose as the sole carbon source. You later found that the bacterium’s growth required an amino acid, lysine, in addition to glucose.
Lysine is a(an) ____ for this bacterium.
A) coenzyme
B) growth factor
C) cofactor
D) inoculum
E) principal carbon source
A) coenzyme
organic cofactors
carry functional groups or electrons from one enzyme to another - non-covalently, loosely bound to enzymes - covalently bound to enzymes
A bacteriostatic agent will
A) decrease the turbidity of the microbial culture.
B) increase the turbidity of the microbial culture.
C) decrease the viable cell count of the microbial culture.
D) kill the microbial cells without lysis.
E) inhibit the growth of the microbial culture without killing.
E) inhibit the growth of the microbial culture without killing.
Gram-negative E. coli treated with lysozyme in an isotonic solution will produce _____. A) protoplast B) spheroplast C) L-form D) cell lysis E) weak peptidoglycan due to less active transglycosylase
B) spheroplast
Group translocation is different from other transport systems in many ways. Which of the following statements is NOT true about this system?
A) It prepares the transported molecule for the next metabolic step.
B) It uses ATP as an energy-source.
C) Since the solute is modified, its exit by the same transporter can be prevented.
D) When the solute is transported, it is usually phosphorylated.
E) It maintains a concentration gradient that favors further import of the solute through the transporter.
D) When the solute is transported, it is usually phosphorylated.
what are the 2 types of cofactors?
- inorganic cofactors - organic cofactors
Neisseria andCampylobacter are ____ because they grow better at places such the intestinal and respiratory tracts where low-oxygen and high-CO 2 are present.
A) capnophiles
B) microaerophiles
C) facultative anaerobes
D) xerophiles
E) halophiles
C) facultative anaerobes
In living cell, enzymes serve as ______
biological catalysts
how are enzymes extremely efficient?
- orienting the substrate into a position that increases the probability of a reaction at active site without increasing temperature - rates 10^8 to 10^10
