Assignment

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.

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

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).

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.

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.

5. What are the steps of the Gram stain? Explain how it discriminates between Gram-positive and Gram-negative cells.
Matching:

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”.

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.

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

Why can’t ribosomal RNA sequencing be used for phylogenetic studies of viruses?

What is a chemolithotroph?

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.

What is endotoxin, and why is it relevant to human health?

What is one major difference between the cytoplasmic membranes of Bacteria and Archaea?

What is a biofilm?

What does the term “enrichment culture” refer to?

True/False: Mark T or F on the line.

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.

Who was the first person to describe bacteria, using a microscope?
A) Sergei Winogradsky
B) Antoni van Leeuwenhoek
C) Martinus Beijerinck
D) Robert Hooke

Which of the following features are variable among bacteria, meaning that not all species possess them?
A) Flagella
B) Type IV pili
C) Capsule
D) All of the above Most prokaryotic cells reside
A) 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) viral
B) bacterial
C) eukaryotic
D) archaeal

A tiny stylus positioned so close to a specimen that weak repulsive forces are established is used in
A) dark-field microscopy.
B) confocal scanning laser microscopy.
C) atomic force microscopy.
D) none of the above.

Which of the following carbon sources would be appropriate for a heterotroph?
A) CO2
B) Glucose
C) H2
D) 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 aIDing 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 source
B) some cells can change their direction of movement by temporarily stopping orchanging the direction of flagellar rotation
C) flagella assist in swimming motility
D) flagellar motion and chemotaxis can be used to preferentially move bacteriatowards a desired nutrient source