Download Spring 2005 - Antelope Valley College

BIOLOGY 204
GENERAL MICROBIOLOGY
INSTRUCTOR: Dr A. Hemsley
ANTELOPE VALLEY COLLEGE
SPRING 2005
THEORY TEST 2
100 POINTS
STUDENT NAME: ___________________________________
STUDENT I.D. NUMBER: _____________________________
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Perusal time = 10 minutes
Test time = 105 minutes
ANSWER ALL QUESTIONS
Read ALL questions carefully during perusal time, you may write if you wish.
Use the back of each sheet if you do not have enough writing space, but please label each answer.
Question subheadings are NOT of equal points value.
Points allocated for each subheading are shown at the end of the question.
GOOD LUCK!
QUESTION 1 (Total =10 points)
Match entries in the left column with answers from the lettered choices in the right column. Write your letter choice
to the far left of each question in the spaces provided. Use each answer only ONCE. (1 Point per correct pair)
_____ 1. Moist heat treatment that will disinfect
a.
Ultra-high temperature
_____ 2. Moist heat treatment that will sterilize
b.
Boiling
_____ 3. Milk pasteurization for 1 second at 140oC
c.
Bacteriostasis
_____ 4. Milk pasteurization for 15 seconds at 72oC
d.
Fungicide
_____ 5.Disinfectant safe to use of living tissue
e.
Sanitization
_____ 6. Prevention of bacterial growth without killing the bacteria present
f.
Pasteurization
_____ 7. Instrument using dry heat to sterilize
g.
High temperature
Short time
_____8. Reduction of pathogen counts on eating and drinking utensils
to safe public health levels
h.
Oven
_____ 9. Agent capable of killing fungi
_____ 10. Method of heat treatment designed to kill vegetative pathogens
i
Antiseptic
j.
Autoclaving
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QUESTION 2 (Total =10 points)
The following growth patterns were found when Cultures A, B, C, D and E were placed in thioglycollate broth tubes
and grown in an incubator overnight without any shaking.
A
B
C
D
E
See Table 6.1 for the growth patterns that should be in the tubes.
With respect to its oxygen preference, describe each of the above cultures and explain the growth pattern seen
A.
B.
C.
D.
E.
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QUESTION 3 (Total =20 points)
A.
Provide two reasons why the structure of quarternary ammonium detergents permits them
to be effective disruptors of plasma membranes.
(4)
B.
Fill In the blanks in the following table:
Name of disinfectant
Mechanism of action
or antiseptic
____________(Oxidizer) Oxidizer of
membranes/proteins
Denatures lipid
membranes
Iodine (Halogen)
(12)
Advantages
Unstable on tissues
Adheres to skin/mucus
membranes
Extensive use In water
disinfection and
sewage treatment
Ethanol
Phenolics
C.
Disadvantages
Unpalatable for water
disinfection
Unstable over long
times In aqueous
solution
Can cause drying of
wounds
Carcinogen
List four principles that we need to consider when choosing an appropriate disinfection
protocol. Explain, with an example for each one, how each principle can Influence the
success of the disinfection process.
(4)
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QUESTION 4 (Total =20 points)
A.
B.
Explain why It Is essential for a species to have a large gene pool, and describe one strategy used by
eukaryotes and one used by prokaryotes to generate a large gene pool.
(6)
Give description of the roles of each of the following RNA molecules within the microbial cell
(6)
messenger RNA
ribosomal RNA
transfer RNA
C.
Describe what is meant by GENOTYPE and PHENOTYPE and give an example of each
(4)
D.
Explain why It Is sometimes possible for microbes with different genotypes to display the same phenotype.
(4)
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QUESTION 5 (Total =20 points)
Fill in the blanks in the following sentences. (1 point per correct sentence)
1.
The nucleotide that pairs with G in RNA is____________________________.
2.
The first codon in all mRNA molecules is____________________________.
3.
One of the three codon sequences that signal protein synthesis termination is ____________________________.
4.
A microbial test commonly performed to detect carcinogens is the ____________________________.
5.
One chemical agent capable of causing mutations is ____________________________.
6.
A DNA mutation where a base change does not affect the protein sequence of the gene product is
called a ____________________________ mutation.
7.
A DNA mutation where a base change affects one amino acid in the protein sequence of the gene
product is called a ____________________________ mutation.
8.
A DNA mutation where a base change introduces a STOP codon in the protein sequence of the gene
product is called a ____________________________ mutation.
9.
A ___________________________ microbe is one that is metabolically active.
10.
____________________________is a mechanism that introduces new genetic material into a bacterium as naked
DNA.
11.
____________________________ is a mechanism that introduces new genetic material into a bacterium by way
of a bacteriophage vector.
12.
____________________________ is a mechanism that introduces new genetic material into a bacterium due to a
mating event initiated by the F plasmid.
13.
Plasmids confer a survival advantage, such as____________________________ to bacteria possessing them.
14.
____________________________ is an enzyme that catalyses the formation of an RNA chain.
15.
The ____________________________ is an enzyme used to cut DNA at specific sequences.
16.
One important recombinant gene product expressed in bacteria is____________________________.
17.
A method of artificially introducing genes into cells is ____________________________ .
18.
The _________________ ________________________
amounts of DNA from a small initial sample.
19.
____________________________ is a process that uses microbes to clean up chemical spills or pollution created
by humans within the natural environment.
20.
One agricultural application of genetic engineering is Improvement In the_____________________________ of
crops.
____________________ is a technique for creating large
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QUESTION 6 (Total =20 points)
A.
The polymerase chain reaction (PCR) is a technique that may be used diagnostically to determine HIV status
in individuals who have engaged in high-risk behaviors. The technique is more costly than other detection
methods. What is an important advantage of using this detection method?
(5)
B.
Describe the steps involved in PCR
C.
PCR uses a DNA polymerase that comes from a thermophilic bacterium Thermus aquaticus, not from our
favorite laboratory pet, Escherichia coli. Explain why this Is so.
(5)
D.
The enzyme DNA Ligase is not needed In PCR. Explain why this is so.
(5)
(5)
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