Chromosome number alteration and prokaryotic gene transfer.
Supplemental Instruction
IowaStateUniversity / Leader: / Matt C.
Course: / Biol/Gen 313
Instructor: / Dr. Myers & Dr. Vollbrecht
Date: / 03/26/2017

Introduction: This worksheet discusses material covered in the twenty-fourth and twenty-fifth lectures(03/10/2017 and 03/20/2017). Chapters6 and 7 examine these topics.

Concepts

  1. Aneuploidy and polyploidy.
  2. Introduction to prokaryotic gene transfer.
  3. High-frequency recombination.

Material

  1. Aneuploidy and polyploidy.

In this section, we’ll examine aneuploidy and polyploidy.

  1. What is the difference between aneuploidy and polyploidy? Which is more likely to be stable?
  1. Determine if the following scenarios are examples of aneuploidy or polyploidy and if so, decide which.
  2. Trisomy 21.
  1. Turner Syndrome.
  1. Human female cells with Barr bodies (inactivated X chromosomes).
  1. Klinefelter Syndrome.
  1. A sample of human smooth muscle arterial wall cells exhibit twice the normal nuclear DNA amount.
  1. What can polyploidy be useful for? What type of polyploidy does this helpful form usually take? How does this arise in broad terms?
  1. Introduction to prokaryotic gene transfer.

In this section, we’ll examine the broader strokes of horizontal gene transfer in prokaryotes.

  1. There are three methods of horizontal gene transfer. What are these?
  1. Describe the contact-dependent form of horizontal gene transfer. What is the factor that a bacterial cell needs to complete this? What does the factor code for?
  1. In the following scenarios, determine if conjugation can occur.
  2. An F+ cell with an F- cell.
  1. An F+ cell with another F+ cell.
  1. An F+ cell with an F- cell with a filter in the way (like the U-tube experiment).
  1. An F+E. coli with an F-S. enterica.
  1. Explain what happens during bacterial transformation.
  1. Explain how viral-mediated horizontal gene transfer occurs.
  1. High-frequency recombination.

Here, we will focus on Hfr mostly as it relates to gene mapping.

  1. When isa bacterial cell be considered Hfr? What term is used to describe F factors that can make Hfr cells?
  1. A bacterial chromosome is known to have genes G, H, I, J, and K which are involved in metabolizing certain substrates. You isolate two Hfr strains with F factors integrated at different sites. You use an interrupted mating test between the Hfr strain and an F- strain and note when growth of formerly F- cells occurs on minimal media plates after a determined amount of time in which mating was allowed. From this, you compile a chart listing the time at which 50% of the formerly F- cells appeared to uptake each of the genes described above.

Sample / G / H / I / J / K
1 / 3 min / 1 min / 3 min / 8 min / 5 min
Sample / G / H / I / J / K
2 / 4 min / 6 min / 5 min / 7 min / 2 min
  1. Which cells are auxotrophic? Which are prototrophic?
  1. Draw the chromosome of the bacterium used in this experiment with the relative locations of the genes described and where the F factors likely integrated.
  1. Performing a similar experiment to the above, but with genes M, N, O, and P, you collect the following data in graphical form.

  1. Draw the chromosome of the bacterium used in this experiment with the relative locations of the genes described and where the F factors likely integrated.

Things to do next

  • Focus your review on things that were difficult from this worksheet. If it was really challenging, don’t worry; these are meant to be tough and push your understanding of the topics we covered.
  • The Hfr material is the most interpretive of these topics. The other material should be mostly definition-based, so memorizing that material with flashcards or another preferred method is a good idea.
  • If you have any questions, ask me in session, in class, or by email. I’m more than happy to help.
  • Next session will be on Tuesday (03/28/2017) from 7:10 to 8:00 PM in Gilman 2109. We will be covering the new material that we’ll talk about in lecture on Monday.