Microbiology Assignment 6 Flashcards

Questions and Answers

What results when a single bacterium reproduces?

Two genetically identical daughter cells

If you begin with six cells, how many cells would you have after three rounds of division?

forty-eight

Which of the following is not a step in bacterial cell division? (Select all that apply)

Cell elongation

Replication of the genetic material

Splitting apart of two new daughter cells

Disappearance of nuclear envelope (correct)

Which step of binary fission is the reason for genetically identical daughter cells?

Replication of the bacterial chromosome Signup and view all the answers

What enables the copied chromosomes to separate during binary fission?

The chromosomes are attached to different parts of the cell membrane, which elongates and thus separates the chromosomes. Signup and view all the answers

How long does it take for the daughter cells to initiate or start the next round of replication?

No time is required -- they are ready to divide immediately after DNA replication and separation of the daughter cells is complete if conditions are right. Signup and view all the answers

Put the following steps of bacterial replication in the correct order, starting from a parent cell: ______.

3, 1, 2, 4 Signup and view all the answers

What would happen if the septum did not form during binary fission?

The parent cell would not have two copies of the chromosomes. Signup and view all the answers

Starting with three cells, how many cells would result from three rounds of replication?

twenty-four Signup and view all the answers

In the figure, which line best depicts a facultative anaerobe in the absence of O2?

Line B Signup and view all the answers

In the figure, which line best depicts a psychrotroph incubated at 0°C?

Line C Signup and view all the answers

Which of the following elements is NOT correctly matched with its cellular function? (Select all that apply)

Phosphorus: used for production of carbohydrates Signup and view all the answers

Salts and sugars work to preserve foods by creating a

hypertonic environment Signup and view all the answers

The term aerotolerant anaerobe refers to an organism that

does not use oxygen but tolerates it Signup and view all the answers

Most bacteria grow at pH

7 Signup and view all the answers

Which of the following pairs of microbe classification terms and optimal growth temperatures is mismatched? (Select all that apply)

Thermophile: growth at 37°C Signup and view all the answers

What does facultative halophile refer to?

S.aureus Signup and view all the answers

Why do all cells need nitrogen?

For building amino acids, proteins, and nucleic acids Signup and view all the answers

Most pathogenic bacteria are thermophiles.

False Signup and view all the answers

Patients with indwelling catheters are susceptible to infections because

biofilms develop on catheters Signup and view all the answers

The majority of hospital-acquired infections are related to

biofilms Signup and view all the answers

Microbes in biofilms are less resistant to antimicrobials than are independent organisms.

False Signup and view all the answers

It is estimated that nearly ______ % of all infections are caused by biofilms.

70% Signup and view all the answers

Antimicrobials can be applied to the surface of catheters and IV tubing to prevent _ ___.

biofilm development Signup and view all the answers

The biosafety level (BSL) for most introductory microbiology laboratories is

BSL-1 Signup and view all the answers

A culture medium consisting of agar, peptone, and beef heart is a

complex medium Signup and view all the answers

For which of the following types of microbes would a microbiologist employ living host cells to support their growth?

Obligate intracellular organisms, such as chlamydias, rickettsias, and viruses Signup and view all the answers

Study Notes

Bacterial Cell Division

A single bacterium reproduces by creating two genetically identical daughter cells.
Starting with six cells, after three rounds of division, there will be forty-eight cells.
Key steps in bacterial cell division include replication of genetic material, cell elongation, septum formation, and separation of daughter cells. The disappearance of the nuclear envelope is not involved.
The replication of the bacterial chromosome ensures that daughter cells are genetically identical.
Chromosomes separate during binary fission because they are attached to different cell membrane areas which elongate.

Initiation of Division

Daughter cells are ready to initiate the next round of replication immediately after the previous round if conditions are favorable.
The correct order of bacterial replication is: chromosome replication, cell elongation, septum formation, and separation of daughter cells.

Consequences of Faulty Division

If the septum does not form during binary fission, the parent cell will not have two chromosome copies.
Starting with three cells, three rounds of replication would yield twenty-four cells.

Microbial Growth and Environmental Factors

A hypertonic environment is created by salts and sugars, helping to preserve foods.
Aerotolerant anaerobes do not use oxygen but can tolerate its presence.
The majority of bacteria prefer a neutral pH of 7 for optimal growth.

Microbial Classification

Thermophiles are incorrectly matched with growth at 37°C; they thrive at higher temperatures.
S. aureus can be classified as a facultative halophile, indicating its tolerance to high salt concentrations.

Nutritional Requirements

Cells require nitrogen for synthesizing amino acids, proteins, and nucleic acids.
Most pathogenic bacteria are not thermophiles, contrary to common assumptions.

Infections and Biofilms

Indwelling catheters pose a risk for infections due to biofilm development on their surfaces.
Hospital-acquired infections are primarily associated with biofilms; approximately 70% of all infections are attributed to these structures.
Microbes in biofilms are more resistant to antimicrobials than independent organisms, challenging treatment efforts.

Safety and Media in Microbiology

Most introductory microbiology labs operate at a biosafety level of BSL-1, indicating the lowest risk level.
A culture medium composed of agar, peptone, and beef heart is classified as a complex medium.
Obligate intracellular organisms, such as chlamydias, rickettsias, and viruses, require living host cells for cultivation.

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Test your knowledge on the key concepts of bacterial cell reproduction and division with these flashcards. Ideal for students tackling Assignment 6 in Microbiology. Challenge yourself to answer questions about cell division processes and outcomes.