exam1 spring 2014

Exam 1 (Biol 120, Spring 2014)

2/21/14 12:00-12:50 pm

50 questions × 3 points = 150 points
1.

Table right compares the shape and size of various prokaryotes. Which one best describes
Escherichia coli?
A) A
B) B
C) C
D) D
E) E

2.

Which is the least permeable through the cell membrane? A) Proton
B) Water
C) Glycerol
D) Tryptophan
E) Glucose

3.

Figure right shows three classes of transport systems.
Which one is using energy?
A) 1
B) 2
C) 3
D) 1 and 2
E) 1, 2 and 3

Use figure right to answer the questions 4 and 5.
4.

Based on the experiment (see right), what is the original cell density (cfu/ml)?
A) 1.59 × 105
C) 3.5 × 105
C) 3.5 × 106
D) 4.5 × 105
E) 4.5 × 106

5.

This procedure is for:
A) Total cell count
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B) Viable cell count
C) Turbidimetric cell count
D) Microscopic count
E) Direct count

6.

Bacteria from the tube (a) of figure right are:
A) Obligate aerobes
B) Obligate anaerobes
C) Facultative aerobes
D) Microaerophiles
E) Aerotolerant anaerobes

7.

Figure below shows how to ( a A) spread B) spread C) streak D) streak 8.

a

) and the purpose is to (

b

b evenly distribute cells isolate a single colony evenly distribute cells isolate a single colony

Which one does NOT involve a membrane structure for energy generation?
A) Aerobic respiration
B) Anaerobic respiration
C) Fermentation
D) Chemolithotrophic life
E) Photosynthesis
2

):

9.

You have a bacterial culture solution. When you directly measured the OD600, of the culture solution, the spectrophotometer showed it was 2. Alternatively, when you did a 10-fold dilution and then measured the
OD600 of the diluted solution, the machine showed it was 0.4. Assuming that OD600=1 is equivalent to 109 cells/ml, how many cells do you have in 1 ml of the original culture?
A) 2 × 108 cells
B) 4 × 108 cells
C) 2 × 109 cells
D) 3 × 109 cells
E) 4 × 109 cells

10. (Figure right) DNA replication and FtsZ ring formation should be coordinated. Which one is happening first?
A) DNA replication
B) FtsZ ring formation

11. Mutations in the FtsZ protein cause a filamentous growth phenotype. Then, what is more likely the function of the FtsZ protein?
A) Speed up the cell division
B) Slow down the cell division

12. Two isotherms in the figure right show the melting temperatures of Escherichia coli and Streptomyces coelicolor. Which one is more likely the E. coli isotherm?
A) a
B) b

E. coli
S. coelicolor

GC ratio (%)
50
72

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Figures below shows the growth of Escherichia coli when fed with lactose and glucose. Use these to answers the questions 13, 14 and 15.

13. How can you best describe this kind of growth?
A) batch
B) chemostat
C) diauxic
D) plate

14. (Fill in) What are needed for blanks ( a ) and ( above. a b A) glucose lactose
B)
lactose glucose C) mostly glucose mostly lactose
D)
mostly lactose mostly glucose

b

15. What would be just happening at the time of C in the left figure?
A) CRP will gain DNA-binding activity.
B) CRP will lose DNA-binding activity.
C) LacI will gain DNA-binding activity.
D) LacI will lose DNA-binding activity.

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) embedded in the left figure

16. Figure below shows an aminoacyl tRNA synthetase. Which amino acid should this enzyme transfer to the tRNA? (Use the codon usage table on right).
A) Ala
B) Val
C) Thr
D) His
E) Trp

17. Let’s say an antibiotic acts by binding to a sigma factor. Then the antibiotic molecule inhibits:
A) DNA replication
B) Transcription
C) Translation
D) Post-translation

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18. The structure highlighted in the A site (figure above) plays an important role in freeing a stalled ribosome. What is it (a) and what is the key element (b)? a b
A) mtRNA
Shine-Dalgarno sequence
B) mtRNA
Stop codon
C) tmRNA
Shine-Dalgarno sequence
D) tmRNA
Stop codon

19. Transcriptional activators act on ( on ( b ) promoters. a b
A) strong strong B) strong weak C) weak strong D) week week a

) promoters and transcriptional repressors act

20. (T/F) Find appropriate words:
Flagella movement of bacteria is powered by ( a b
A) ATP cell membrane
B) ATP outer membrane
C) Proton motive force cell membrane
D) Proton motive force outer membrane

a

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) and it is anchored to the (

b

).

Figure below shows electron acceptor groups were isolated from Escherichia notsocoli. Use the figure to answer the questions 21, 22 and 23.

21. Where would you find proteins containing these electron acceptor groups?
A) Cytoplasm
B) Cell membrane
C) Outer membrane
D) Periplasmic space
E) Cell wall

22. What would be the second molecule in the most probable linear electron transport scheme?
A) a
B) b
C) c
D) d
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23. Which groups would transfer proton(s) in addition to electron(s)?
A) a & b
B) b & c
C) c & d
D) d & a

24. (Fill-in) Bacteria stain as gram-positive or gram-negative because of differences in the (
A) Cell wall
B) Cytoplasm
C) Cell membrane
D) Chromosome
E) Outer membrane

).

25. Below, you are seeing a simplified description of lac operon, especially upstream of coding region
(lacZYA). This non-coding region has three binding sites; one for RNA polymerase, one for an activator and one for a repressor. Where would be the binding site for RNA polymerase?
A) A
B) B
C) C

26. Lipid monolayers found in the cell membranes of certain species of the domain archaea can be an adaptation strategy to (
) environment.
A) Acidic
B) Basic
C) Cold
D) Hot
E) Osmotic

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27. In figure right, a heavy loopful of bacterial cells from an agar culture was mixed on a slide
(right) with a drop of 30% hydrogen peroxide. The immediate appearance of bubbles is indicative of which reaction? 28. Figure right shows ( mechanism. A) Allosteric
B) Covalent

) inhibition

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29. Which one is not a high energy compound in the cell?
A) Adenosine triphosphate
B) Acetyl-CoA
C) Acetyl phosphate
D) Glucose-6-phosphate
E) Phosphoenolpyruvate

See figure and table below to find answers for questions 30 and 31.

30. Figure above depicts which process?
A) DNA replication
B) Transcription
C) Translation
D) Reverse transcription
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31. To transcribe the genes 1-6 (figure left), which sigma factor do you need?
A) RpoS
B) RpoH
C) RpoD
D) RpoN
E) FecI

32. Under the condition where methionine must be the first amino acid, what is the fourth amino acid of the protein encoded by the following mRNA?
5'-CCUCAUAUGCGCCAUUAUAAGUGACACACA-3'
A) Alanine
B) Aspartic acid
C) Phenylalanine
D) Serine
E) Tyrosine

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33. Figure below shows two major protein export systems. What are the two key proteins? a b
A) SRP
SecA
B) SecA
SRP
C) SRP
Tat
D) SecA
Tat

34. Which is NOT true about genetic code and codons?
A) Codons are degenerate.
B) One lysyl tRNA can bind to both AAA and AAG codons.
C) The genetic code is universal.
D) In an organism, some codons are greatly preferred over others even though they encode the same amino acid.
E) There are three stop codons and only one start codon.
35. (Fill-in) There are two characteristic of all the DNA polymerases. 1. All the DNA polymerases can only extend nucleic acid chains: i.e., they cannot initiate new ones. In other words, they all require
(
a
). 2. All the DNA polymerases add mononucleotides to the ( b ) of deoxyribose and therefore elongate nucleic acid only at the ( b ) end. a b
A) a primer
5’
B) a template
5’
C) a primer
3’
D) a template
3’

36. For the signaling molecules that cannot penetrate through the cell membrane, bacteria use
(
) which allows for transferring the signal to DNA-binding transcriptional regulators (located in the cytoplasm) for gene regulation.
A) One component systems
B) Two component systems
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37. Figure below shows a riboswitch mechanism. The signaling metabolite binds to an mRNA the critical consequence of which is the blocking of the DNA segment ( a
) acting as ( b ). a b
A) 1
Transcription termination
B) 3
Transcription termination
C) 1
Ribosome binding site
D) 3
Ribosome binding site

38. Which statement is NOT true about gene regulation by antisense RNA?
A) Antisense RNAs bind to their mRNA complements to form double-stranded RNAs.
B) Antisense RNA is transcribed from the nontemplate strand of the target gene that yields the target mRNA.
C) Only a relatively short piece of antisense RNA is needed to block transcription of mRNA, and therefore the “anti-gene” that encodes the antisense RNA is much shorter than the gene that encodes the original message.
D) Antisense RNA can be used to enhance translation of target mRNA.
E) Antisense RNA is also used for eukaryotic systems.

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See figures below to find answers for questions 39, 40 and 41.

39. Which one involves an allosteric change of RNA polymerase (rather than recruitment) as the basis for gene activation?
A) A
B) B
C) C
D) D
E) E

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40. Which ones involve the regulation of sigma factor(s) to eventually regulate a set of genes?
A) A & B
B) A & D
C) B & D
D) C & D
E) B & E
41. Which one best describes the bacterial regulation mechanism of sensing population density through small molecules. Such regulation mechanism explains phenomena such as bioluminescence by Aliivibrio fischeri and biofilm formation by Pseudomonas aeruginosa and
Staphylococcus aureus.
A) A
B) B
C) C
D) D
E) E
42. Which structure has the closest connection to microbial taxis?
A) Endospore
B) Pili
C) Flagella
D) Gas vesicle
E) Fimbriae
43. (Fill-in) A typical prokaryotes has ( a genes found inside the cell. a b
A)
One
Linear
B)
One
Circular
C)
Two
Linear
D)
Two
Circular

)( b

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) chromosome(s) containing all (or most) of the

See figures below to find answers for questions 44 and 45.

44. Which one contains cells containing dipicolinic acid (which traps water and intercalates in DNA) and small acid-soluble proteins (which protect DNA)?
A) A
B) B
C) C
D) D
45. Which one contains the cellular component describing the following? This component has various functions: helps attach to host cells; helps attach to solid surfaces; helps evade host immune systems; helps trap water.
A) A
B) B
C) C
D) D
46. (T/F) ATP synthase can use ATP to generate the proton motive force.
A) True
B) False
47. In the history of microbiology, who discovered that using solid media provided a simple way of obtaining pure cultures?
A) Sergei Winogradsky
B) Louis Pasteur
C) Robert Koch
D) Robert Hooke

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48. Figure below compares death rates between year 1990 and today, for the leading causes of death in the United States. The comparison shows the microbiologists’ Success in Preventing Infectious
Diseases. Which one is for today?
A) A
B) B

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49. Table below compares three domains of life for their chromosomes and DNA replication. Based on the table, can you say that chromosome replication of Archaea is similar to that of eukaryotes than that of eubacteria.
A) Yes
B) No

50. Figure below depicts shared transcription and translation features among three domains of life.
What might the feature of #1 or #9?
A) Shine-Dalgarno sequences
B) Multiple transcription factors (for transcription)
C) Ribosomes synthesize proteins
D) Polycistronic mRNA

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