UT Dallas BIOL 300 Exam 1

07 Jul UT Dallas BIOL 300 Exam 1

Write in complete sentences. I will take off points for not using complete sentences. You can draw diagrams to supplement your answers.

Long answer:

1a. Describe Pasteur’s experiment disproving spontaneous generation. (6 points)

b. How might this experiment have been affected by the presence of endospore contamination in Pasteur’s culture media? (2 points)

 

2. Specifically state each of Koch’s four postulates. (6 points) Then explain how you would use each of Koch’s postulates to determine that Neisseria meningitidis is a causative agent of infectious meningitis (infection of the brain). (6 points)

 

3. Draw the Gram-negative cell wall and label all the components. Write out full names of components – don’t use abbreviations. Be detailed. You don’t need to draw chemical structures. (7.5 points)

4. Describe and/or draw the structure of E. coli peptidoglycan, including any unusual features. Write out full names of components – don’t use abbreviations. Be detailed. You don’t need to draw chemical structures. (6 points)

 

5. What are the steps of the Gram stain? (4 points) Explain how it discriminates between Gram-positive and Gram-negative cells. (4 points)

Matching: (13.5 points total)

From the list below, determine whether each statement applies to prokaryotic cells (P), eukaryotic cells (E), both, or neither (N). If both, write “both” and not “B”. (1.5 points each)

 

______ Has a nucleus

 

__ ____ Requires sources of carbon and energy for growth

 

__ Utilizes the processes of replication, transcription and translation

 

__ ____ Has a DNA genome

 

_ ____ Has an RNA genome

 

____ Bacteria and Archaea

 

__ ____ Has a cytoplasmic membrane

 

______ Transcription and translation are coupled

 

_____ Evolves by heritable variations in genome sequence

 

 

Short answer: Answer with 1-2 complete sentences. (17 points total)

Why can’t many nutrients, and specifically hydrophilic molecules, pass freely through the cytoplasmic membrane? (2 points)

 

Why can’t ribosomal RNA sequencing be used for phylogenetic studies of viruses? (2 points)

 

What is a chemolithotroph? (2 points)

 

Your friend went to Yellowstone this summer on a research trip. She says she isolated a novel hyperthermophilic microbe. She tells you that the organism grows in the lab at temperatures ranging from 10°C to 122°C, and grows perfectly well at room temperature. Explain why she is wrong about this organism being a hyperthermophile.(2 points)

 

 

What is endotoxin, and why is it relevant to human health? (3 points)

 

 

 

 

What is one major difference between the cytoplasmic membranes of Bacteria and Archaea? (2 points)

 

What is a biofilm? (2 points)

 

What does the term “enrichment culture” refer to? (2 points)

 

 

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True/False: Mark T or F on the line. (2 points each, 10 points total)

______ Peptidoglycan and LPS are specific to Bacteria and are recognized by the human immune system.

 

______ There are many known species of pathogenic Archaea.

 

______ All microbes on Earth have been discovered and catalogued.(everyone in class got this right)

 

_____ Lipoteichoic acid is found in the cell walls of gram-negative bacteria.

 

______ All bacteria are the same size and shape as E. coli. (everyone in class got this right)

 

 

Multiple choice: Mark your answer on the line. (2 points each, 18 points total)

 

 

______ Who was the first person to describe bacteria, using a microscope?A) Sergei WinogradskyB) Antoni van LeeuwenhoekC) Martinus BeijerinckD) Robert Hooke

 

______ Which of the following features are variable among bacteria, meaning that not all species possess them?A) FlagellaB) Type IV piliC) CapsuleD) All of the above

 

______ Most prokaryotic cells resideA) on Earth’s surface.B) in lakes, rivers, and oceans.C) in and on nonprokaryotic organisms (including humans and other animals).D) in the oceanic and terrestrial subsurfaces. Which are largely uncharted and whichmeans we know little about most prokaryotic life on Earth.

 

______ According to our present understanding, mitochondria and chloroplasts are ________ in origin.A) viralB) bacterialC) eukaryoticD) archaeal

 

______ A tiny stylus positioned so close to a specimen that weak repulsive forces are established is used inA) dark-field microscopy.B) confocal scanning laser microscopy.

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C) atomic force microscopy.D) none of the above.

 

______ Which of the following carbon sources would be appropriate for a heterotroph?A) CO2B) GlucoseC) H2D) Both A and B would be appropriate

 

______ What is the function of the E. coli PTS system?A) Providing protons for flagellar motility/transport.B) Trapping a sugar within the cell by adding a phosphate group to it.C) Polyhydroxyalkanoate transport and synthesis.D) Peptidoglycan transport and synthesis.

 

______ Which of the following statements are true about endospore formation?A) All bacteria can sporulate.B) Sporulation begins when excess nutrient sources are present.C) Endospores lack genomic DNA.D) Dipicolinic acid and small acid-soluble proteins are present.

 

______ Which of the following statements is not true about flagella?A) flagellar rotation does not require an energy sourceB) some cells can change their direction of movement by temporarily stopping orchanging the direction of flagellar rotationC) flagella assist in swimming motilityD) flagellar motion and chemotaxis can be used to preferentially move bacteriatowards a desired nutrient source