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5.3: Bacteria Reproduction

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How can bacteria reproduce so rapidly?

Bacteria can divide very rapidly. This image is of a growing colony of E. coli bacteria. In the right environment, a single E. coli can divide to form a colony of hundreds of bacteria in just a few hours.

Bacteria Reproduction

Bacteria, being single-celled prokaryotic organisms, do not have a male or female version. Bacteria reproduce asexually. In asexual reproduction , the "parent" produces a genetically identical copy of itself.

Binary Fission

Bacteria reproduce through a process called binary fission . During binary fission, the chromosome copies itself, forming two genetically identical copies. Then, the cell enlarges and divides into two new daughter cells. The two daughter cells are identical to the parent cell. Binary fission can happen very rapidly. Some species of bacteria can double their population in less than ten minutes!

Exchanging DNA

Sexual reproduction does not occur in bacteria. But not all new bacteria are clones. This is because bacteria can still combine and exchange DNA. This exchange occurs in three different ways:

  1. Conjugation : In conjugation, DNA passes through an extension on the surface of one bacterium and travels to another bacterium ( Figure below ).
  2. Transformation : In transformation, bacteria pick up pieces of DNA from their environment.
  3. Transduction : In transduction, viruses that infect bacteria carry DNA from one bacterium to another.

Bacteria can exchange small segments of DNA through conjugation. Notice two bacterial cells are attached by a short extension. DNA can be exchanged through this extension.

Vocabulary

  • asexual reproduction : Process of forming a new individual from a single parent.
  • binary fission : Type of asexual reproduction in bacteria where a single cell divides into two cells.
  • conjugation : Transfer of DNA from one bacterium to another.
  • transduction : DNA transfer from one bacterium to another by a virus.
  • transformation : Picking up pieces of DNA from a bacterium’s environment.

Summary

  • Bacteria reproduce by binary fission, resulting in two daughter cells identical to the parent cell.
  • Bacteria can exchange DNA through the processes of conjugation, transformation, or transduction.

Practice

Use the resources below to answer the questions that follow.

  1. What is the circular DNA in bacteria called?
  2. How do the genes of the daughter cell differ from the genes of a mother cell?
  3. How many steps are involved with binary fission? What are they?
  1. There are approximately 7 billion humans on the planet. How long would it take some bacteria to make 7 billion copies of themselves?
  2. Why is this trait in bacteria useful to scientists?

Review

  1. How do bacteria reproduce?
  2. How do bacteria exchange DNA?

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Difficulty Level:

At Grade

Grades:

7 , 8

Date Created:

Nov 29, 2012

Last Modified:

Oct 04, 2014
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