Chapter 6
Select those cell-counting methods that enable only living cells to be counted.
Viable Plate Count Flow Cytometry
After binary fission, daughter cells will differ genetically.
False
Bacteria have an average generation time of 24 hours.
False
Cells cannot begin a new round of replication until they have completely finished dividing.
False
T/F Both human and bacterial cells divide by mitosis.
False
Consider the following hypothetical conditions: A population of 10,000 bacteria has a doubling time of 20 minutes, under a given set of growth conditions. The culture is allowed to grow for 2 hours. Select the number of bacteria that best predicts the population size at the end of the 2 hours incubation. Assume there is no lag phase.
64,000
How is cell division triggered?
Cell division is triggered exclusively when cells attain a threshold mass and length.
Death Phase
Cells die at an exponential rate and unable to multiply
Stationary Phase
Cells enter a survival mode Stop growing or greatly reduce their metabolic activity/ growth due to depleted nutrients/ build up of waste
Exponential Phase
Cells reach their optimal doubling time increasing by a population of 2 this remains constant as long as the environment is favorable
Helicase and polymerase
DNA helicase is responsible for unwinding the DNA double helix so replication can begin. DNA polymerase is responsible for adding the nucleotides to the chain.
Select characteristics of biofilms that differentiate them from planktonic bacteria.
Microorganisms exist as part of a diverse interdependent community. Microorganisms are readily eradicated using antibiotics. Microorganisms participate in quorum sensing. Microorganisms live singly, independently.
Microbial growth can be affected by a variety of physical and chemical environmental factors.
Physical factors include temperature, various types of radiation, barometric pressure, osmotic pressure, and extreme drying/dehydration. Chemical factors that can affect growth include the presence of oxygen and carbon dioxide, presence of appropriate nutrients, and pH.
Lag Phase
Poplulation of cell is not increasing at this time Metabolically Active Binary Fission
Which enzyme is NOT involved in DNA replication?
RNA polymerase
A closed culture system is used to determine a population growth curve.
True
T/F Environmental factors control microbial growth through their influence on enzyme activity.
True
The degree of turbidity in a culture correlates to the amount of cell growth.
True
The time that it takes for a freshly inoculated agar culture to develop visible colonies is principally governed by the generation time of the inoculated species.
True
The patient asks the RN to describe the pathophysiology of a urinary tract infection. The RN describes the process of bacterial urea digestion, releasing ammonium. How does the RN most accurately describe the resultant pH following bacterial urine decomposition, facilitating growth of pathogens?
alkaline
Most cultured bacteria tend to multiply by.
binary fission
The time required for one complete cycle of binary fission is known as ________ time or generation time.
doubling
Carbon, nitrogen, oxygen, and hydrogen are considered ________ nutrients because they are required in relatively large quantities and cannot be manufactured by microbes themselves.
essential
Choose the phase of the bacterial growth curve during which a bacterial population has the briefest doubling time.
exponential growth phase
Cell division is triggered exclusively when cells attain a threshold mass.
false
DNA helicase is responsible for adding nucleotides to the growing end of the DNA.
false
The energy source for contraction of the FtsZ ring during cell division comes from _____.
hydrolysis of GTP
Choose the term that describes an organism that lacks superoxide dismutase and catalase enzymes to test your understanding of the role of these enzymes in microbial growth.
obligate anaerobe
Cells must ______ their DNA prior to cell division
replicate
Please choose the answer that best completes the blanks of this sentence in the correct order. A _________ derives its nutrients and energy from the organic matter of dead organisms, whereas a _________ lives in or on another living organism and derives its nutrients and energy from that living organism.
saprobe; parasite
The FtsZ protein is needed to form the
septum