Microbiology 1st Edition By Wessner – Test Bank A+

$35.00
Microbiology 1st Edition By Wessner – Test Bank A+

Microbiology 1st Edition By Wessner – Test Bank A+

$35.00
Microbiology 1st Edition By Wessner – Test Bank A+

Question Type: Multiple Choice

1) Which one of the following elements is considered a microelement, usually required in minute amounts in microbiological media?

  1. a) phosphate
  2. b) potassium
  3. c) iron
  4. d) manganese
  5. e) magnesium

Answer: d

Difficulty: Easy

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

2) What is the function of siderophores?

  1. a) Transporting waste products out of the cell.
  2. b) Binding iron for transport into the cell.
  3. c) Binding glucose for transport into the cell.
  4. d) Transporting proteins out of the cell.
  5. e) Moving potassium into the cell for osmotic regulation.

Answer: b

Difficulty: Easy

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

3) An autotroph is defined as an organism that uses _____ as a source of _____.

  1. a) sunlight; energy
  2. b) organic compounds; carbon
  3. c) organic compounds; energy
  4. d) inorganic compounds; energy
  5. e) carbon dioxide; carbon

Answer: e

Difficulty: Easy

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

4) A heterotroph is defined as an organism that uses _____ as a source of _____.

  1. a) sunlight; energy
  2. b) organic compounds; carbon
  3. c) organic compounds; energy
  4. d) inorganic compounds; energy
  5. e) carbon dioxide; carbon

Answer: b

Difficulty: Easy

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

5) What is the most readily useable form of nitrogen by microorganisms?

  1. a) dinitrogen
  2. b) ammonium ion
  3. c) nitrate
  4. d) nitrite
  5. e) nitric oxide

Answer: b

Difficulty: Easy

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

6) What is nitrogen fixation?

  1. a) The oxidation of nitrate to ammonia for assimilation.
  2. b) The oxidation of ammonia to nitrate for assimilation.
  3. c) The reduction of dinitrogen to ammonia for assimilation.
  4. d) The reduction of nitrate to dinitrogen for assimilation.
  5. e) The release of an amino group from an amino acid for assimilation.

Answer: c

Difficulty: Medium

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

7) What is the most abundant form of nitrogen in the biosphere?

  1. a) ammonia
  2. b) nitrate
  3. c) nitrite
  4. d) dinitrogen
  5. e) nitrous oxide

Answer: d

Difficulty: Medium

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

8) A phototroph is defined as an organism that uses _____ as a source of _____.

  1. a) carbon dioxide; carbon
  2. b) organic compounds; carbon
  3. c) inorganic compounds; energy
  4. d) sunlight; energy
  5. e) organic compounds; energy

Answer: d

Difficulty: Easy

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

9) A lithotroph is defined as an organism that uses _____ as a source of _____.

  1. a) inorganic compounds; energy and electrons
  2. b) organic compounds; energy and electronss.
  3. c) inorganic compounds; carbon
  4. d) sunlight; energy
  5. e) carbon dioxide; energy

Answer: a

Difficulty: Medium

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

10) What is the most common solidifying agent used in microbiological media?

  1. a) gelatin
  2. b) agar
  3. c) alginate
  4. d) silica
  5. e) polyacrylamide

Answer: b

Difficulty: Easy

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

11) Which one of the following is NOT a physical factor that affects the growth rate of cells?

  1. a) nutrient concentration
  2. b) temperature
  3. c) pressure
  4. d) light intensity
  5. e) radiation

Answer: a

Difficulty: Easy

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

12) What term applies to a microbe that can synthesize all of its cellular constituents from a simple carbon source and inorganic salts?

  1. a) autotroph
  2. b) heterotroph
  3. c) auxotroph
  4. d) prototroph
  5. e) a chemotroph

Answer: d

Difficulty: Easy

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

13) Term that applies to a bacterium that has an absolute requirement of oxygen for growth..

  1. a) aerobe
  2. b) anaerobe
  3. c) aerotolerant anaerobe
  4. d) facultative anaerobe
  5. e) facultative aerobe

Answer: a

Difficulty: Easy

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

14) Term for a bacterium that does not use oxygen for growth, but will grow in the presence of oxygen.

  1. a) aerobe
  2. b) anaerobe
  3. c) aerotolerant anaerobe
  4. d) facultative anaerobe
  5. e) facultative aerobe

Answer: c

Difficulty: Easy

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

15) The enzyme catalase is used to detoxify which harmful oxygen species?

  1. a) hydroxyl radical
  2. b) superoxide
  3. c) hydrogen peroxide
  4. d) ozone
  5. e) singlet oxygen

Answer: c

Difficulty: Easy

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

16) What is the term for microbes that grow optimally at a pH below 5.5?

  1. a) alkalophiles
  2. b) psychrophiles
  3. c) halophiles
  4. d) acidophiles
  5. e) barophiles

Answer: d

Difficulty: Easy

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

17) Term for microbes that grow optimally at very high salt concentrations.

  1. a) osmolphiles
  2. b) barophiles
  3. c) halophiles
  4. d) psychrophiles
  5. e) thermophiles

Answer: c

Difficulty: Easy

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

18) Term for microbes that grow optimally at a pH above 8.5.

  1. a) acidophiles
  2. b) alkalophiles
  3. c) barophiles
  4. d) psychrophiles
  5. e) halophiles

Answer: b

Difficulty: Easy

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

19) Term applied to microbes that grow optimally at temperatures below 15°C.

  1. a) psychrophiles
  2. b) barophiles
  3. c) alkalophiles
  4. d) mesophiles
  5. e) halophiles

Answer: a

Difficulty: Easy

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

20) Enrichment media that contains starch as the sole carbon source is encouraging the growth of microbes that produce _____ .

  1. a) glucose
  2. b) the enzyme amylase
  3. c) the enzyme cellulase
  4. d) all twenty amino acids
  5. e) all required vitamins

Answer: b

Difficulty: Medium

Learning Objective: LO 6.3 Explain how bacteria may be cultured in the laboratory and the methods used to study unculturable microbes.

Section Reference: Section 6.3 Growing microorganisms in the laboratory

21) In the environment, one microorganism often provides a nutrient for another microbe that is unable to synthesize the nutrient by itself. What is this type of relationship called?

  1. a) auxotrophy
  2. b) prototrophy
  3. c) syntrophy
  4. d) oligotrophy
  5. e) eutrophy

Answer: c

Difficulty: Easy

Learning Objective: LO 6.3 Explain how bacteria may be cultured in the laboratory and the methods used to study unculturable microbes.

Section Reference: Section 6.3 Growing microorganisms in the laboratory

22) Which of these methods can be used to obtain a viable cell count?

  1. a) counting chamber direct count
  2. b) turbidity measurement
  3. c) plate counts of serial dilutions
  4. d) loop dilution
  5. e) optical density

Answer: c

Difficulty: Easy

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

23) What would you use to measure the optical density of a bacterial culture?

  1. a) a Petroff-Hauser counting chamber
  2. b) a flow cytometer
  3. c) the plate count method
  4. d) a spectrophotometer
  5. e) a microscope

Answer: d

Difficulty: Easy

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

24) The plate count method was used to estimate the number of bacteria in a culture over time. Serial dilutions were made of culture samples at various time points. A 0.1 ml portion of the 10-6 dilution was spread over the surface of a nutrient agar plate for each time point. The plates were incubated for 24 hrs and the colony forming units (CFU) were counted on each plate. A total of 45 colonies were counted on the plate for the 30 minute time point. What was the cell population for this time point?

  1. a) 45 X 104 CFU/ml
  2. b) 45 X 105 CFU/ml
  3. c) 45 X 106 CFU/ml
  4. d) 45 X 107 CFU/ml
  5. e) 45 X 108 CFU/ml

Answer: d

Difficulty: Medium

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

25) In reference to microbial growth, what conditions prompt the “stringent response”?

  1. a) A shift from a warm to a cold environment.
  2. b) A shift from a nutrient rich to a nutrient poor environment.
  3. c) A shift from an oxygen rich to an oxygen poor environment.
  4. d) A shift from a state of resistance to susceptibility to a bacteriophage.
  5. e) A shift from a light to a dark environment.

Answer: b

Difficulty: Medium

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

26) Fresh media is inoculated with an actively growing Escherichia coli culture. You measure the optical density (OD) at the time of inoculation and record avalue of of 0.05) Two hours later you take another reading and record a optical density of 0.2) What is the generation time for your culture?

  1. a) 30 minutes
  2. b) 40 minutes
  3. c) 50 minutes
  4. d) 60 minutes
  5. e) Cannot determine from the information given.

Answer: d

Difficulty: Medium

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

27) If a cell culture contains 400 cells/ml at time = 0 and it has a generation time of 30 minutes, how many cells (cells/ml) will be present after 2 hours of incubation?

  1. a) 1200 cells/ml
  2. b) 1600 cells/ml
  3. c) 2400 cells/ml
  4. d) 3200 cells/ml
  5. e) 6400 cells/ml

Answer: e

Difficulty: Medium

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

28) What is the mean growth rate for a culture that has a generation time of 1 hour?

  1. a) 1 hr.
  2. b) 2 hr.
  3. c) 1 hr-1.
  4. d) 2 hr-1.
  5. e) Cannot determine from the information given.

Answer: c

Difficulty: Easy

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

29) How long would it take a culture of E. coli with a starting cell density of 1 X 105 cells/ ml to reach a cell density of 1 X 108 cells/ml if it had a generation time of 30 minutes?

  1. a) 3 hours
  2. b) 4 hours
  3. c) 5 hours
  4. d) 6 hours
  5. e) 7 hours

Answer: c

Difficulty: Medium

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

30) If you had an E. coli culture with a starting cell density of 1 X 106 cells/ml and it had a generation time of 40 minutes, what would be the cell density after incubation for 6 hours?

  1. a) 3 X 108 cells/ml
  2. b) 5.1 X 108 cell/ml
  3. c) 6.3 X 108 cells/ml
  4. d) 9.4 X 108 cells/ml
  5. e) 1 X 109 cells/ml

Answer: b

Difficulty: Hard

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

31) What is a chemosta?

  1. a) A system used for the continuous culture of microbial cells.
  2. b) A chemical used as a substrate for growth of microbial cells.
  3. c) The maximum growth rate that can be obtained for a useable substrate.
  4. d) A batch culture that uses a defined medium for growth.
  5. e) A nutrient that is able to control the growth rate of a bacterial culture.

Answer: a

Difficulty: Easy

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

32) In order for a chemostat to operate properly, what must the reservoir contain?

  1. a) a complex medium
  2. b) vitamins
  3. c) all twenty amino acids
  4. d) a limiting nutrient
  5. e) oxygen

Answer: d

Difficulty: Medium

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

33) During steady state growth in a chemostat, the growth rate of the cells is equivalent to:

  1. a) the nutrient concentration.
  2. b) the generation time.
  3. c) the cell yield.
  4. d) the flow rate.
  5. e) the dilution rate.

Answer: e

Difficulty: Medium

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

34) Which method listed below will result in sterilization of an environmental water sample?

  1. a) Boiling the sample for ten minutes.
  2. b) Adding bleach to the sample.
  3. c) Autoclaving the sample.
  4. d) Heating the sample to 70°C for 30 minutes.
  5. e) Microwaving the sample for 3 minutes.

Answer: c

Difficulty: Easy

Learning Objective: LO 6.5 Discuss sterilization, disinfection, autoclaving, pasteurization, antiseptic, antimicrobial, and the various methods used to remove/neutralize microbes.

Section Reference: Section 6.5 Eliminating microbes and preventing their growth

35) Which is the best definition of an antiseptic?

  1. a) A chemical agent that is applied to hospital equipment to kill or inhibit microbes.
  2. b) A chemical agent that is applied to living tissue to kill and inhibit microbes.
  3. c) An antibiotic that is applied to living tissue.
  4. d) A physical agent that is used to sterilize hospital equipment.
  5. e) A physical agent that is used on human tissue to inhibit microbial growth.

Answer: b

Difficulty: Easy

Learning Objective: LO 6.5 Discuss sterilization, disinfection, autoclaving, pasteurization, antiseptic, antimicrobial, and the various methods used to remove/neutralize microbes.

Section Reference: Section 6.5 Eliminating microbes and preventing their growth

36) Alcohols like ethanol and isopropanol are commonly used as antiseptics because they are very effective at reducing the bacterial load. What is thier mode of action?

  1. a) disrupting the plasma membrane
  2. b) inhibiting DNA replication
  3. c) inhibiting protein synthesis
  4. d) disruption of the peptidoglycan
  5. e) inhibiting transcription

Answer: a

Difficulty: Medium

Learning Objective: LO 6.5 Discuss sterilization, disinfection, autoclaving, pasteurization, antiseptic, antimicrobial, and the various methods used to remove/neutralize microbes.

Section Reference: Section 6.5 Eliminating microbes and preventing their growth

37) Many disinfectants are strong oxidizing agents and disrupt many cellular functions. Which of these is an example of an oxidizing agent?

  1. a) isopropanol
  2. b) carbolic acid
  3. c) triclosan
  4. d) chlorine bleach
  5. e) phenol

Answer: d

Difficulty: Medium

Learning Objective: LO 6.5 Discuss sterilization, disinfection, autoclaving, pasteurization, antiseptic, antimicrobial, and the various methods used to remove/neutralize microbes.

Section Reference: Section 6.5 Eliminating microbes and preventing their growth

38) Many pharmaceutical products are heat sensitive so they are sterilized:

  1. a) by ultraviolet radiation.
  2. b) by ionizing radiation.
  3. c) with ozone gas.
  4. d) with chlorine gas.
  5. e) by freezing.

Answer: b

Difficulty: Medium

Learning Objective: LO 6.5 Discuss sterilization, disinfection, autoclaving, pasteurization, antiseptic, antimicrobial, and the various methods used to remove/neutralize microbes.

Section Reference: Section 6.5 Eliminating microbes and preventing their growth

Question Type: True/False

39) An autotroph is an organism that obtains its energy from the sun.

Answer: False

Difficulty: Easy

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

40) A heterotroph is an organism that uses organic carbon as its carbon source.

Answer: True

Difficulty: Easy

Learning Objective: LO 6.1 Define the various metabolisms common to microbes.

Section Reference: Section 6.1 Nutritional Requirements of Microorganisms

41) Generation time is the average time it takes an actively growing cell in a population to divide.

Answer: True

Difficulty: Easy

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

42) Prototrophic microbes need to be grown on a complex medium because they have several growth factor requirements.

Answer: False

Difficulty: Easy

Learning Objective: LO 6.3 Explain how bacteria may be cultured in the laboratory and the methods used to study unculturable microbes.

Section Reference: Section 6.3 Growing microorganisms in the laboratory

43) Microbes that have an absolute requirement for oxygen are called obligate aerobes.

Answer: True

Difficulty: Easy

Learning Objective: LO 6.3 Explain how bacteria may be cultured in the laboratory and the methods used to study unculturable microbes.

Section Reference: Section 6.3 Growing microorganisms in the laboratory

44) The bile salts in MacConkey agar, which inhibits the growth of many bacteria, make this media differential in nature.

Answer: False

Difficulty: Medium

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

45) Pasteurization is a method of sterilization.

Answer: False

Difficulty: Medium

Learning Objective: LO 6.5 Discuss sterilization, disinfection, autoclaving, pasteurization, antiseptic, antimicrobial, and the various methods used to remove/neutralize microbes.

Section Reference: Section 6.5 Eliminating microbes and preventing their growth

46) The use of a good antiseptic, such as Betadine, results in sterilization.

Answer: False

Difficulty: Medium

Learning Objective: LO 6.5 Discuss sterilization, disinfection, autoclaving, pasteurization, antiseptic, antimicrobial, and the various methods used to remove/neutralize microbes.

Section Reference: Section 6.5 Eliminating microbes and preventing their growth

Question Type: Text Entry

47) A device used for the continuous culturing of bacteria is called a _________.

Answer: chemostat

Difficulty: Medium

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

48) A microbe that grows optimally at a temperature below 15°C is called a __________.

Answer: psychrophile

Difficulty: Easy

Learning Objective: LO 6.3 Explain how bacteria may be cultured in the laboratory and the methods used to study unculturable microbes.

Section Reference: Section 6.3 Growing microorganisms in the laboratory

50) A microbe that grows in the presence of oxygen but does not use oxygen for growth is called a(n) __________ __________.

Answer: aerotolerant anaerobe

Difficulty: Easy

Learning Objective: LO 6.3 Explain how bacteria may be cultured in the laboratory and the methods used to study unculturable microbes.

Section Reference: Section 6.3 Growing microorganisms in the laboratory

51) The process commonly used by the dairy industry to reduce the number of microbes in milk and destroy any pathogens that may be present is called ______________.

Answer: Pasteurization

Difficulty: Medium

Learning Objective: LO 6.5 Discuss sterilization, disinfection, autoclaving, pasteurization, antiseptic, antimicrobial, and the various methods used to remove/neutralize microbes.

Section Reference: Section 6.5 Eliminating microbes and preventing their growth

52) Nucleic acids strongly absorb _____________ radiation of 260 nm.

Answer: ultraviolet

Difficulty: Medium

Learning Objective: LO 6.5 Discuss sterilization, disinfection, autoclaving, pasteurization, antiseptic, antimicrobial, and the various methods used to remove/neutralize microbes.

Section Reference: Section 6.5 Eliminating microbes and preventing their growth

Question Type: Essay

53) The growth curve generated for a microbial batch culture consists of four phases. Explain what is happening to the culture during each of the phases.

Answer:

Difficulty: Medium

Learning Objective: LO 6.2 Describe the various environmental conditions that affect microbial growth and how bacteria can be categorized by their growth preferences.

Section Reference: Section 6.2 Factors affecting microbial growth

Solution: When a culture is freshly inoculated the cells usually enter into an adjustment period to their new environment. This phase of growth is referred to as the lag phase and is characterized by very little increase in cell number. The cells are making new proteins and enzymes during this phase to enable them to grow optimally in their new environment. After a period of adjustment the cells enter the logarithmic or exponential phase. During this period of growth the cells are growing at their maximal rate. Eventually some nutrient will become limiting in the growth medium and the cells will enter a phase of growth in which their growth rate will began to slow as the cells enter into the stationary phase. During the first part of this phase the cell will respond by preparing itself for a period of starvation. New genes will be expressed that will help the cell survive a long period of nutrient depletion. If the cells stay in the stationary phase for a long time the cells will begin to die. This is referred to as the death phase.

54) What are the ingredients in MacConkey agar makes it both selective and differential? Give an example for its use.

Answer:

Difficulty: Medium

Learning Objective: LO 6.4 Describe the methods used to determine the density and expansion of bacterial cultures.

Section Reference: Section 6.4 Measuring microbial population growth

Solution: Bile salts in MacConkey agar make the media selective for microbes that grow in the gut. Intestinal microbes have developed the ability to survive the harsh detergent-like effects of bile salts and will readily grow on this medium. The medium also contains lactose and a pH indicator for the detection of lactose fermentation. Microbes that can ferment lactose will turn red due to acid production and microbes that are unable to ferment lactose will remain uncolored. This medium is commonly used to select for and differentiate enteric bacteria. For example, the medium will differentiate between the common lactose fermenters like E. coli and non-fermenter pathogens like Salmonella and Shigella.

55) Compare and contrast sterilization to disinfection. Give an example for both.

Answer:

Difficulty: Easy

Learning Objective: LO 6.5 Discuss sterilization, disinfection, autoclaving, pasteurization, antiseptic, antimicrobial, and the various methods used to remove/neutralize microbes.

Section Reference: Section 6.5 Eliminating microbes and preventing their growth

Solution: Sterilization is the complete elimination of all living cells including endospores, and viruses. Disinfection is the reduction in the microbial load through the use of a chemical or physical agent. The disinfectant will inhibit the growth or kill the microbes and viruses that may be present on a surface. Disinfection usually does not result in sterilization. Examples of sterilization techniques are autoclaving, dry heat sterilization, and the use of ionizing radiation. Examples of disinfectants are phenolic compounds, oxidizing agents like chlorine and iodine, and alcohols.

56) Would ionizing radiation be safe to use on food? Why?

Answer:

Difficulty: Medium

Learning Objective: LO 6.5 Discuss sterilization, disinfection, autoclaving, pasteurization, antiseptic, antimicrobial, and the various methods used to remove/neutralize microbes.

Section Reference: Section 6.5 Eliminating microbes and preventing their growth

Solution: Yes, ionizing radiation would be safe to use on food. In some countries it is used on food to increase the shelf life of the food product. In the United States ionizing radiation is commonly used to sterilize drugs because many drugs are heat labile and would be destroyed by an autoclaving process. The radiation source never comes in direct contact with the drug or food product and thus, it does not present a health hazard.

Package Title: Test Bank

Course Title: Wessner1e

Chapter Number: 7

Question Type: Multiple Choice

1) What did the experiment by Fred Griffith in 1928 with the R and S strains of Streptococcus pneumoniae demonstrate?

  1. a) DNA was the genetic material in cells.
  2. b) R strain phenotype could spontaneously revert to S strain phenotype.
  3. c) Genetic material from one strain could be transferred to another strain.
  4. d) The ability of these bacteria to kill mice.
  5. e) That some strains of Streptococcus were not pathogenic.

Answer: c

Difficulty: Easy

Learning Objective: LO 7.1 Describe the history of DNA research, giving examples of important experiments.

Section Reference: Section 7.1 The role of DNA

2) What did the experiment by Avery, MacLeod, and McCarty in 1944 with the R and S strains of Streptococcus pneumoniae demonstrate?

  1. a) DNA was the genetic material in cells.
  2. b) R strain phenotype could spontaneously revert to S strain phenotype.
  3. c) Genetic material from one strain could be transferred to another strain.
  4. d) The ability of these bacteria to kill mice.
  5. e) That some strains of Streptococcus were not pathogenic.

Answer: a

Difficulty: Easy

Learning Objective: LO 7.1 Describe the history of DNA research, giving examples of important experiments.

Section Reference: Section 7.1 The role of DNA

3) The Hershey and Chase experiment was able to conclusively demonstrate that DNA, not protein, was the genetic material. They were able to distinguish DNA from protein since labeled _____ incorporated into DNA while labeled _____ incorporated into proteins.

  1. a) nitrogen; sulfur
  2. b) magnesium; nitrogen
  3. c) nitrogen; magnesium
  4. d) phosphorous; sulfur
  5. e) sulfur; nitrogen

Answer: d

Difficulty: Medium

Learning Objective: LO 7.1 Describe the history of DNA research, giving examples of important experiments.

Section Reference: Section 7.1 The role of DNA

4) The Watson and Crick model showed that in the DNA molecule:

  1. a) purines paired with pyrimidines, and the strands align anti-parallel to one another.
  2. b) purines paired with purines, and the strands align parallel to one another.
  3. c) purines paired with purines, and the strands align anti-parallel to one another.
  4. d) purines paired with pyrimidines, and the strands align parallel to one another.
  5. e) pyrimidines paired with pyrimidines, and the strands align parallel to one another.

Answer: a

Difficulty: Medium

Learning Objective: LO 7.1 Describe the history of DNA research, giving examples of important experiments.

Section Reference: Section 7.1 The role of DNA

5) How do nucleotides connect to adjacent nucleotides in the Watson-Crick model of DNA?

  1. a) Via a covalent bond between the 3’ hydroxyl of one nucleotide and the 2’ deoxy of the other.
  2. b) Via a hydrogen bond between the nitrogenous base of one nucleotide and the nitrogenous base of the other.
  3. c) Via a hydrogen bond between the nitrogenous base of one nucleotide and the 5’ phosphate of the other.
  4. d) Via a covalent bond between the 3’ hydroxyl of one nucleotide and the nitrogenous base of the other.
  5. e) Via a covalent bond between the 3’ hydroxyl of one nucleotide and the 5’ phosphate of the other.

Answer: e

Difficulty: Easy

Learning Objective: LO 7.1 Describe the history of DNA research, giving examples of important experiments.

Section Reference: Section 7.1 The role of DNA

6) The Watson-Crick model of DNA shows that the base adenine pairs with:

  1. a) cytosine while guanine pairs with thymine.
  2. b) guanine while cytosine pairs with thymine.
  3. c) thymine while cytosine pairs with guanine.
  4. d) either thymine or guanine, while cytosine pairs with either thymine or guanine.
  5. e) either thymine or cytosine while guanine pairs with either thymine or cytosine.

Answer: c

Difficulty: Easy

Learning Objective: LO 7.1 Describe the history of DNA research, giving examples of important experiments.

Section Reference: Section 7.1 The role of DNA

7) The main differences between Bacteria and Archaea chromosomal DNA when compared to Eukarya chromosomal DNA, is that the Bacteria or Archaea chromosome usually:

  1. a) is circular while Eukarya is linear.
  2. b) is diploid while Eukarya is haploid.
  3. c) consist of several chromosomes while Eukarya has a single chromosome.
  4. d) contains the base uracil while Eukarya has thymine in place of uracil.
  5. e) is found in a non-condensed form while Eukarya DNA is highly condensed and packaged.

Answer: a

Difficulty: Easy

Learning Objective: LO 7.1 Describe the history of DNA research, giving examples of important experiments.

Section Reference: Section 7.1 The role of DNA

8) Replication of the bacterial chromosome begins at how many locations?

  1. a) one
  2. b) two
  3. c) three
  4. d) four
  5. e) five

Answer: a

Difficulty: Easy

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

9) What is the first protein to bind to the oriC region of the DNA molecule to start the replication process?

  1. a) DNA polymerase
  2. b) the primase
  3. c) DnaA
  4. d) gyrase
  5. e) DnaI

Answer: c

Difficulty: Medium

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

10) After the DNA is unwound at the site of DNA replication initiation,what binds to the unwound DNA to prevent it from reannealing?

  1. a) DNA gyrase
  2. b) single-stranded DNA binding protein
  3. c) DnaA
  4. d) DNA polymerase
  5. e) DnaB

Answer: b

Difficulty: Easy

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

11) What, in bacteria, is analogous to the autonomously replicating sequence (ARS) in yeast?

  1. a) the promoter
  2. b) a plasmid
  3. c) a transposon
  4. d) the oriC
  5. e) a prophage

Answer: d

Difficulty: Easy

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

12) Which statement below is FALSE regarding replication of the bacterial chromosome?

  1. a) Replication occurs in a bidirectional manner from the origin of replication.
  2. b) The leading strand is replicated in the 5’ to 3’ direction and the lagging strand in the 3’ to 5’ direction.
  3. c) The primase adds a short RNA primer to serve as a starting point for the DNA polymerase to add new bases.
  4. d) DNA replication is a semi-conservative process, where one strand serves as a template for the synthesis of a complementary strand.
  5. e) The incoming nucleotide triphosphate is covalently attached to the free 3’ hydroxyl.

Answer: b

Difficulty: Medium

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

13) Which enzyme removes the RNA primer and fills in the gap during DNA replication in bacteria?

  1. a) DNA polymerase III
  2. b) DNA polymerase I
  3. c) primase
  4. d) ligase
  5. e) DNAase

Answer: b

Difficulty: Easy

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

14) What are the main enzymes responsible for replication of DNA in eukaryal cells?

  1. a) DNA pol III and DNA pol I
  2. b) DNA pol III and DNA pol α
  3. c) DNA pol I and DNA pol ε
  4. d) DNA pol α and DNA pol ε
  5. e) DNA pol ε and DNA pol δ

Answer: e

Difficulty: Medium

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

15) Replication termination in E. coli involves which two proteins?

  1. a) Tus protein and topoisomerase II.
  2. b) helicase and DnaG.
  3. c) helicase and topoisomerase II.
  4. d) Tus protein and DnaG.
  5. e) Tus protein and helicase.

Answer: a

Difficulty: Medium

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

16) Term for a special sequence at the end of the chromosome in eukaryal cells.

  1. a) a terminator
  2. b) a centromere
  3. c) a telomere
  4. d) an antiorigin.
  5. e) an enhancer

Answer: c

Difficulty: Easy

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

17) Which enzyme is responsible for adding the final bases to the end of a chromosome during DNA replication in eukaryal cells?

  1. a) DNA polδ
  2. b) DNA polα
  3. c) DNA primase B
  4. d) telomerase
  5. e) topoisomerase

Answer: d

Difficulty: Easy

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

18) Which of these best differentiates DNA and RNA?

  1. a) RNA is single-stranded and DNA is double stranded.
  2. b) RNA contains ribose and DNA contains deoxyribose.
  3. c) RNA contains the base uracil in place of thymine, which is in DNA.
  4. d) Both a and b are true.
  5. e) a, b, and c are true.

Answer: e

Difficulty: Easy

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

19) A gene can best be described as a segment of DNA that:

  1. a) encodes for a protein.
  2. b) encodes for a protein or functional RNA.
  3. c) is transcribed as well as the associated regulatory regions.
  4. d) encodes for a protein as well as the associated regulatory regions.
  5. e) is transcribed.

Answer: c

Difficulty: Medium

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

20) Messenger RNA (mRNA) can best be described as a molecule that contains the code for a:

  1. a) protein.
  2. b) polypeptide.
  3. c) protein, rRNA or tRNA.
  4. d) polypeptide, tRNA, or rRNA.
  5. e) polypeptide or regulatory RNA.

Answer: b

Difficulty: Easy

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

21) What are micro RNAs?

  1. a) mRNAs that encode for regulatory proteins
  2. b) small regulatory RNAs
  3. c) tRNAs
  4. d) rRNAs
  5. e) small mRNAs

Answer: b

Difficulty: Easy

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

22) For the initiation of transcription in bacteria, RNA polymerase binds to what region on the gene?

  1. a) promoter
  2. b) operator
  3. c) enhancer region
  4. d) origin of replication
  5. e) Shine-Dalgarno sequence

Answer: a

Difficulty: Easy

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

23) What is the sigma factor of the RNA polymerase holoenzyme responsible for?

  1. a) initiation of transcription
  2. b) recognition of the promoter region
  3. c) transcription elongation
  4. d) transcription termination
  5. e) ribosome binding

Answer: b

Difficulty: Easy

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

24) Most bacterial promoters consist of two regions: __________ and ___________.

  1. a) Pribnow box and operator.
  2. b) enhancer region and operator.
  3. c) enhancer region and -35 region.
  4. d) -35 region and operator.
  5. e) Pribnow box and -35 region.

Answer: e

Difficulty: Easy

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

25) In eukaryal cells, what does RNA polymerase II transcribe?

  1. a) tRNA genes
  2. b) small regulatory RNAs
  3. c) the 5S and 18S rRNAs
  4. d) mRNA genes
  5. e) rRNAs genes

Answer: d

Difficulty: Medium

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

26) What does Rho-independent termination of transcription in bacteria involve?

  1. a) The formation of a hairpin loop followed by a poly A sequence.
  2. b) The formation of a hairpin loop only.
  3. c) A poly U sequence followed by a poly A sequence.
  4. d) The formation of a hairpin loop followed by a poly U sequence.
  5. e) A poly A sequence followed by a hairpin loop.

Answer: d

Difficulty: Easy

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

27) Transcription termination in eukaryal cells is more complex than in bacterial cells as the RNA molecule undergoes further processing before becoming a functional mRNA. Which of these BEST describes this processing?

  1. a) Capping the 3’ end with 7-methyl-guanosine, adding a poly-A sequence at the 5’ end and removing internal sequences called introns.
  2. b) Capping the 3’ end with 7-methyl-guanosine, adding a poly-A sequence at the 5’ end and removing internal sequences called exons.
  3. c) Capping the 5’ end with 7-methyl guanosine, adding a poly-A sequence at the 3’ end and removing internal sequences called introns.
  4. d) Capping the 5’ end with 7-methyl-guanosine, adding a poly-A sequence at the 3’ end and removing internal sequences called exons.
  5. e) Capping the 3’ end with 7-methyl-guanosine and adding a poly-A sequence at the 3’ end.

Answer: c

Difficulty: Easy

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

28) What is a codon?

  1. a) Four bases on the mRNA that is read by the ribosome in the 3’ to 5’ direction.
  2. b) Four bases on the mRNA that is read by the ribosome in the 5’ to 3’ direction.
  3. c) Three bases on the mRNA that is read by the ribosome in the 3’ to 5’ direction.
  4. d) Three bases on the mRNA that is read by the ribosome in the 5’ to 3’ direction.
  5. e) Two bases on the mRNA that is read by the ribosome in the 5’ to 3’ direction.

Answer: d

Difficulty: Easy

Learning Objective: LO 7.4 Describe the components of protein synthesis found in the bacterial cell, the process of translation, and the differences in translation between prokaryotes and eukaryotes.

Section Reference: Section 7.4 Translation

29) Initiation of translation in bacteria starts with the binding of the 30S ribosomal subunit to the mRNA molecule. The ribosomal binding site is nearer the _________ end of the mRNA molecule and is called the ________.

  1. a) 3’; Pribnow box
  2. b) 3’; Shine-Dalgarno sequence
  3. c) 3’; Rho sequence
  4. d) 5’; Shine-Dalgarno sequence
  5. e) 5’; Rho sequence

Answer: d

Difficulty: Easy

Learning Objective: LO 7.4 Describe the components of protein synthesis found in the bacterial cell, the process of translation, and the differences in translation between prokaryotes and eukaryotes.

Section Reference: Section 7.4 Translation

30) The mRNA of bacterial cells is often polycistronic. What does this term mean?

  1. a) Tt can be translated more than once.
  2. b) It contains the code for multiple peptides.
  3. c) Tt can be translated from either end.
  4. d) Tt is transcribed from multiple sites on the chromosome.
  5. e) The translated protein may be modified in different ways.

Answer: b

Difficulty: Easy

Learning Objective: LO 7.4 Describe the components of protein synthesis found in the bacterial cell, the process of translation, and the differences in translation between prokaryotes and eukaryotes.

Section Reference: Section 7.4 Translation

31) After the translational process the polypeptide folds into the appropriate conformation for proper functioning. What group of proteins aids in protein folding?

  1. a) proteases
  2. b) cytokines
  3. c) chaperonins
  4. d) peptidases
  5. e) lipases

Answer: c

Difficulty: Easy

Learning Objective: LO 7.4 Describe the components of protein synthesis found in the bacterial cell, the process of translation, and the differences in translation between prokaryotes and eukaryotes.

Section Reference: Section 7.4 Translation

32) Which of these would a signal peptide be used for?

  1. a) To regulate translation.
  2. b) To move a protein to the outside of the cell.
  3. c) To help a protein fold correctly.
  4. d) To help regulate the activity of an enzyme.
  5. e) To initiate DNA replication.

Answer: b

Difficulty: Easy

Learning Objective: LO 7.4 Describe the components of protein synthesis found in the bacterial cell, the process of translation, and the differences in translation between prokaryotes and eukaryotes.

Section Reference: Section 7.4 Translation

33) Which of these is a term for a point mutation that results in a change in the amino acid specificity of the codon?

  1. a) frameshift
  2. b) silent
  3. c) nonsense
  4. d) missense
  5. e) amber

Answer: d

Difficulty: Easy

Learning Objective: LO 7.5 Explain the genetic code, the various types of mutations, and how mutations lead to changes in an organism.

Section Reference: Section 7.5 The effects of mutations

34) Which of these is a point mutation that results in changing a codon from an amino acid codon to a stop codon?

  1. a) frameshift
  2. b) silent
  3. c) nonsense
  4. d) missense
  5. e) deletion

Answer: c

Difficulty: Easy

Learning Objective: LO 7.5 Explain the genetic code, the various types of mutations, and how mutations lead to changes in an organism.

Section Reference: Section 7.5 The effects of mutations

35) Which of these results from a deletion of base pairs such that the amino acid sequence is disrupted from that point downward?

  1. a) transversion mutation
  2. b) transition mutation
  3. c) nonsense mutation
  4. d) missense mutation
  5. e) frameshift mutation

Answer: e

Difficulty: Easy

Learning Objective: LO 7.5 Explain the genetic code, the various types of mutations, and how mutations lead to changes in an organism.

Section Reference: Section 7.5 The effects of mutations

Question Type: True/False

36) The DNA replication process in Archaea more closely resembles that in Eukarya than in Bacteria.

Answer: True

Difficulty: Easy

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

37) In DNA replication nucleotides are always added in the 5’ to 3’ direction.

Answer: True

Difficulty: Easy

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

38) Replication of eukaryal DNA requires RNA primer synthesis.

Answer: True

Difficulty: Medium

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

39) In the same bacterial cell, different sigma factors are able to control the expression of large blocks of genes.

Answer: True

Difficulty: Easy

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

40) The RNA polymerase in Archaea is more similar to Bacteria RNA polymerase than Eukarya RNA polymerase II.

Answer: False

Difficulty: Medium

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

41) All living organisms use the same genetic code for the translation of mRNA.

Answer: True

Difficulty: Easy

Learning Objective: LO 7.4 Describe the components of protein synthesis found in the bacterial cell, the process of translation, and the differences in translation between prokaryotes and eukaryotes.

Section Reference: Section 7.4 Translation

Question Type: Text Entry

42) Basic proteins that help to package the DNA in eukaryal cells are called ________.

Answer: histones

Difficulty: Easy

Learning Objective: LO 7.1 Describe the history of DNA research, giving examples of important experiments.

Section Reference: Section 7.1 The role of DNA

43) The origin of replication site in yeast is called the _____ _______ sequence.

Answer: autonomously replicating

Difficulty: Medium

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

44) The site on the DNA molecule that is recognized by the sigma subunit of the RNA polymerase for binding to start transcription is called the _________.

Answer: promoter

Difficulty: Easy

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

45) The -10 element of the bacterial promoter is also referred to as the _______ _____.

Answer: Pribnow box

Difficulty: Easy

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

46) The Shine-Dalgarno sequence on a mRNA is recognized by the __________ of the 30S ribosome.

Answer: 16S rRNA

Difficulty: Easy

Learning Objective: LO 7.4 Describe the components of protein synthesis found in the bacterial cell, the process of translation, and the differences in translation between prokaryotes and eukaryotes.

Section Reference: Section 7.4 Translation

Question Type: Essay

47) Describe the structure of DNA according to the Watson – Crick Model.

Answer:

Difficulty: Easy

Learning Objective: LO 7.1 Describe the history of DNA research, giving examples of important experiments.

Section Reference: Section 7.1 The role of DNA

Solution: Watson and Crick determined that DNA was double-stranded in structure with the strands being antiparallel to one another. That is, one strand arranged in the 5’ to 3’ direction and the complementary strand running in the 3’ to 5’ direction. The strands are polymers of four deoxynucleotides covalently bonded to one another via the 5’ phosphate of the deoxyribose of one nucleotide to the deoxyribose 3’ hydroxyl of the adjacent nucleotide. The other important part of their model is base pairing between the two strands. The base adenine always pairs with thymine and guanine always pairs with cytosine through hydrogen bonding. Hydrogen bonding holds the two strands together, forming a coil or helix type structure.

48) Describe the process of DNA replication initiation in Bacteria.

Answer:

Difficulty: Medium

Learning Objective: LO 7.2 Describe the components of bacterial DNA replication.

Section Reference: Section 7.2 DNA replication

Solution: The initiation of DNA replication occurs at a specific site on the chromosome called the oriC. The oriC site contains several 9-base pair repeats that serve as binding sites for the DnaA proteins. Several DnaA proteins bind and interact with 13-base pair repeats, causing the DNA to unwind, and strand separation to occur. The enzymes DNA helicase and gyrase will move into this site unwinding the DNA further. Single-stranded DNA binding protein will bind to the unwound single stranded DNA to prevent the DNA from winding back upon itself. A primase will now be able to synthesize a short primer strand of RNA to facilitate the binding of the DNA polymerase. DNA polymerase will begin to catalyze the addition of deoxynucleotides starting at the primer.

49) Describe the process of mRNA processing in eukaryal cells.

Answer:

Difficulty: Medium

Learning Objective: LO 7.3 Discuss the types of RNA found in the bacterial cell, the process of transcription, and the differences in transcription between prokaryotes and eukaryotes.

Section Reference: Section 7.3 Transcription

Solution: RNA polymerase II will transcribe the pre-mRNA in the eukaryal nucleus. Immediately after RNA transcription the RNA will be processed to form a functional mRNA. The 5’ end of the RNA molecule will be capped with 5’-methyl guanosine, and the 3’ end will be polyadenylated by a poly(A)-polymerase, creating a long polyA-tail. Most eukaryal RNAs also contain untranslated region called introns. These will be removed, leaving behind the exons, which will be joined together to create a functional mRNA.

50) Why is the genetic code considered degenerate?

Answer:

Difficulty: Medium

Learning Objective: LO 7.5 Explain the genetic code, the various types of mutations, and how mutations lead to changes in an organism.

Section Reference: Section 7.5 The effects of mutations

Solution: The genetic code is referred to as being degenerate because more than one codon represents an amino acid. In addition, the multiple codons that represent a particular amino acid usually only differ in the third base.

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