Question 1

Which phase of the eukaryotic cell cycle is primarily responsible for DNA synthesis, and what is the main event occurring during this phase?

Accepted Answer

S phase; DNA replication

Question 2

During binary fission in bacteria, which protein forms a ring at the future site of division and is essential for septum formation?

Accepted Answer

FtsZ

Question 3

A culture of *E. coli* starts with 5 cells and grows exponentially for 3 hours with a generation time of 20 minutes. Calculate the final number of cells using the exponential growth equation $$N = N_0$ 2^n.$$

Accepted Answer

$$N = 5 	imes 2^9$ = 2,560$$

Question 4

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

Accepted Answer

DNA gyrase

Question 5

What is the function of the Min proteins during bacterial cell division?

Accepted Answer

They ensure the divisome forms at the cell center.

Question 6

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

Accepted Answer

It binds and transports peptidoglycan precursors across the cytoplasmic membrane.

Question 7

A batch culture of bacteria is inoculated into fresh medium. Which phase is characterized by the synthesis of new enzymes required for growth but not an increase in cell number?

Accepted Answer

Lag phase

Question 8

Which of the following statements about the structure of peptidoglycan is correct?

Accepted Answer

It is composed of repeating units of N-acetylglucosamine and N-acetylmuramic acid linked by glycosidic bonds and cross-linked by peptides.

Question 9

In a chemostat, which two parameters must be controlled to maintain a microbial population in exponential growth?

Accepted Answer

Dilution rate and concentration of limiting nutrients

Question 10

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

Accepted Answer

Bacteria use Ter sites and Tus proteins, while eukaryotes use telomerase.

Question 11

Which protein is responsible for forming filamentous spiraled bands that help direct new cell wall synthesis in rod-shaped bacteria?

Accepted Answer

MreB

Question 12

A culture of *Vibrio natriegens* starts with 7 cells, grows exponentially for 1 hour, and has a generation time of 10 minutes. Calculate the final cell number using $$N = N_0$ 2^n.$$

Accepted Answer

$$N = 7 	imes 2^6$ = 448$$

Question 13

Which of the following best describes the function of FtsI proteins during bacterial cell division?

Accepted Answer

They are transpeptidases that insert new peptidoglycan into the expanding cell wall.

Question 14

Which of the following is a practical implication of exponential microbial growth in food products such as milk?

Accepted Answer

Spoilage is most significant during the later stages of exponential growth.

Question 15

Which of the following equations correctly relates the number of generations ($$n$$), total time of exponential growth ($$t$$), and generation time ($$g$$)?

Accepted Answer

$$n = t / g$$

Question 16

Which of the following is NOT a type of unequal cell division in prokaryotes?

Accepted Answer

Binary fission

Question 17

Which phase of the microbial growth curve is characterized by the depletion of essential nutrients and accumulation of toxic products?

Accepted Answer

Stationary phase

Question 18

Which of the following best describes the role of transglycosylases in bacterial cell wall synthesis?

Accepted Answer

They form glycosidic bonds between sugars in peptidoglycan.

Question 19

Which of the following is a correct statement about the structure of the bacterial chromosome?

Accepted Answer

It is circular and contains a single origin of replication.

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

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