Q: A culture of *E. coli* is started with 10 cells and allowed to grow exponentially for 2 hours. If the generation time is 30 minutes, how many cells will be present at the end? Use the formula $N = N_0 2^n$.

$N = 10 \times 2^4 = 160$ cells

Question 1

Which of the following best describes the role of the FtsZ protein during bacterial cell division?

Accepted Answer

It forms a ring at the future site of the septum, guiding the formation of the divisome and initiating cell division.

Question 2

A culture of *E. coli* is started with 10 cells and allowed to grow exponentially for 2 hours. If the generation time is 30 minutes, how many cells will be present at the end? Use the formula $N = N_0 2^n$.

Accepted Answer

$N = 10 	imes 2^4 = 160$ cells

Question 3

Which enzyme is responsible for introducing negative supercoils into bacterial DNA, aiding in DNA compaction?

Accepted Answer

DNA gyrase

Question 4

During which phase of the eukaryotic cell cycle does DNA synthesis occur?

Accepted Answer

S phase

Question 5

Which of the following is a key difference between bacterial and eukaryotic chromosome replication?

Accepted Answer

Bacteria use a single origin of replication, while eukaryotes use multiple origins.

Question 6

A batch culture of bacteria enters stationary phase. Which of the following best explains this observation?

Accepted Answer

Essential nutrients are depleted and/or toxic products have accumulated.

Question 7

Which protein helps ensure that the divisome forms at the cell center in bacteria?

Accepted Answer

Min proteins

Question 8

Which of the following best describes the function of bactoprenol in peptidoglycan synthesis?

Accepted Answer

It transports peptidoglycan precursors across the cytoplasmic membrane.

Question 9

A culture of *Vibrio natriegens* starts with 8 cells and grows exponentially for 1 hour with a generation time of 10 minutes. How many cells are present at the end? Use $N = N_0 2^n$.

Accepted Answer

$N = 8 	imes 2^6 = 512$ cells

Question 10

Which of the following is NOT a function of the divisome in bacterial cell division?

Accepted Answer

Initiation of DNA replication

Question 11

Which of the following statements about peptidoglycan structure is correct?

Accepted Answer

It consists of glycan chains cross-linked by short peptides.

Question 12

Which phase of the microbial growth curve is characterized by the synthesis of new enzymes needed for biosynthesis but little to no cell division?

Accepted Answer

Lag phase

Question 13

Which of the following best explains why supercoiling is essential for bacterial chromosomes?

Accepted Answer

It compacts the DNA to fit inside the small bacterial cell.

Question 14

Which of the following is a correct description of the function of MreB in bacteria?

Accepted Answer

It forms spiral-shaped filaments that help determine cell shape and direct cell wall synthesis.

Question 15

Which of the following events occurs LAST during binary fission in bacteria?

Accepted Answer

Formation of the septum and cell separation

Question 16

Which of the following is a practical implication of exponential microbial growth in food safety?

Accepted Answer

Food spoilage can occur rapidly during later stages of exponential growth.

Question 17

Which of the following best describes the function of FtsI (a penicillin-binding protein) in bacterial cell division?

Accepted Answer

It catalyzes the cross-linking of peptidoglycan strands during cell wall synthesis.

Question 18

Which of the following is a key feature of a chemostat that distinguishes it from a batch culture?

Accepted Answer

It maintains cell populations in exponential growth by continuously adding fresh medium and removing waste.

Question 19

Which of the following is the correct formula for calculating the number of generations ($n$) if you know the total time of exponential growth ($t$) and the generation time ($g$)?

Accepted Answer

$n = \frac{t}{g}$

Microbial Growth and Cell Division: Structure, Function, and Dynamics

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