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CR: Bacteria Reproduction Lesson

Wash or Sanitize?

Does hand sanitizer work as well as washing your hands?

Is it scientifically correct? Check out the following lessons to find out.

How Does Bacteria Reproduce?

 

Two types of reproduction are seen in bacteria: binary fission and conjugation.
Binary Fission Conjugation

In binary fission, a bacterium doubles its size by elongating. It also replicates its DNA before dividing in half, producing 2 identical cells. This is asexual reproduction.

Conjugation is a process where two bacteria can transfer genetic material from one cell to another. They do this by using pili (singular: pilus) that link one bacterium to the other. The genetic material (called an F plasmid) is copied and then transferred; the F plasmid is a ring of circular DNA that frequently contains antibiotic resistance genes. Therefore, conjugation will double the number of resistant bacteria in a population.

Steps to Binary Fission:

Steps to

Conjugation:

Binary Fission Steps, description below

See description of diagram Links to an external site.

Conjugation Steps, description below

See description of diagram Links to an external site.

Do Bacteria Ever Go Dormant?

YES!

When the environment gets tough and food gets scarce, some bacteria can form an endospore. The bacteria divides within its cell wall and one of the two cells engulfs the other, becoming dormant. Dormancy is a state of inactivity in some organisms where growth and metabolism temporarily stop. The endospore that is formed is highly resistant to destruction.

Two images. Left: an endospore. Right: Culture B. subtilus endospores (green) and non-dormant cells (red)

Endospores can be revived after decades of dormancy; they will start to grow quickly when conditions are favorable.

Pasteurization is a process of heating and cooling food products repeatedly so that the endospores which break out of dormancy into regular bacterial form during cooling will be killed if heated again.

Let's Think!

How is binary fission similar to eukaryotic mitosis? How is it different? 

Challenge and Before You Go

Practice Time! Use the knowledge you learned from the lesson to complete the practice activities below.

 

 Before You Go - You Need To Know

The following key points are from the explore section of the lesson. You must know the following information before moving to the next lesson. This is just a summary of the key points.

  1. What are the two ways bacteria can reproduce?
    • Binary fission (cell dividing in half to produce two cells) and Conjugation (transfer of genetic information from one cell to another)
  2. What is an endospore?
    • A tough, protective covering that bacteria form when conditions become harsh. The bacteria go into a state of dormancy. When conditions become better, the endospore disappears.
  3. What is dormancy?
    • A state of inactivity in some organisms where growth and metabolism stop.

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