Horizontal Gene Transfer: Uptake, Contact and Delivery · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.
En anglais

Three ways to borrow genes

Science · Microbiology · ages 20-21
Name ______________________   Date ____________

  1. Which route transfers DNA through direct contact between a living donor and a recipient?

    • Transformation through uptake
    • Conjugation through contact
    • Transduction through phages

  2. Which route delivers bacterial DNA inside a bacteriophage particle?

    • Transformation
    • Conjugation
    • Transduction

  3. Transformation requires a competent recipient able to take up naked environmental DNA.

    Circle one:   True   False

  4. DNase acts before uptake. Controls confirm destruction of all free DNA, viable recipients and functioning contact and phage routes. Gene transfer continues. Which conclusion is justified?

    • Transformation cannot explain the remaining transfer
    • Phage delivery is established as the remaining transfer route
    • Direct-contact transfer is established as the remaining route

  5. A membrane prevents cells from crossing or touching across it. Controls show free DNA and the relevant phage can pass. Transfer still occurs across the membrane. Which conclusion is justified?

    • Transformation and conjugation remain possible
    • Transformation and transduction remain possible
    • Conjugation and phage-mediated transduction remain possible

  6. A gene transfers from bacterial lineage X into lineage Y. Why might its ancestry tree differ from the host-cell tree?

    • The gene's history includes movement between lineages
    • The gene's history follows only vertical inheritance
    • The host-cell tree follows movement between lineages

  7. A DNA fragment enters a recipient, is degraded and leaves no retained copy. This observation proves that the recipient's descendants inherited the gene.

    Circle one:   True   False

  8. A student estimates cell ancestry from one resistance gene that may have transferred between lineages. Which change best addresses this limitation?

    • Compare more sequence sites within that resistance gene
    • Compare independent genes inherited mainly from parent to offspring
    • Compare copies of that resistance gene from more sampled bacterial lineages
LightMySky · lightmysky.comW1-mt_mrmn0_nQf7-s1

Answer key

For grown-ups. Fold this page away before handing over the rest.

Three ways to borrow genes W1-mt_mrmn0_nQf7-s1

  1. Conjugation through contact · Direct donor-recipient contact identifies conjugation. A pilus helps establish contact in many systems, but it is not the defining feature of every system.
  2. Transduction · A bacteriophage is a virus of bacteria. Delivery of bacterial DNA in a phage particle is transduction.
  3. True · Competence is the ability to take up naked DNA. That uptake defines transformation.
  4. Transformation cannot explain the remaining transfer · Transformation needs naked DNA before uptake. Its verified removal excludes that route here, while the controls leave the other routes possible.
  5. Transformation and transduction remain possible · The barrier excludes donor-recipient contact, so conjugation cannot explain transfer across it. Transformation and transduction remain possible.
  6. The gene's history includes movement between lineages · The gene crossed between lineages. Its ancestry therefore need not follow only the parent-to-offspring history of its host cells.
  7. False · Entry alone does not establish inheritance. The stated loss leaves no retained copy for descendants to inherit.
  8. Compare independent genes inherited mainly from parent to offspring · Independent genes with evidence of mainly vertical inheritance provide a broader check on cell ancestry than one potentially transferred gene.
Worksheet · LightMySky