Annotation, Orthologues and Comparative Genomics · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Same genes, different species, shared jobs

Science · Genetics & Evolution · ages 21-22
Name ______________________   Date ____________

  1. One ancestral gene became two copies in the same genome. What are the copies?

    • Orthologues
    • Paralogues
    • Sister chromatids

  2. Human and mouse carry genes from one gene in their last common ancestor. What are they?

    • Orthologues
    • Paralogues
    • Alleles of one locus

  3. An annotation transferred by similarity is a confirmed result needing no test.

    Circle one:   True   False

  4. A sequence is unchanged across distant species. What does that suggest?

    • Mutations there were harmful, so it likely matters
    • The species were recently cloned
    • Sequencers made the same error twice

  5. Why does the orthologue versus paralogue difference matter for function?

    • Paralogues always die out quickly
    • Orthologues usually keep the old job; duplicates may wander
    • Orthologues never mutate at all

  6. What is a limit of the conservation argument?

    • Conserved sequences cannot be sequenced
    • Distant species share no DNA at all
    • Some sequences persist for structural reasons; proof needs experiments

  7. A new gene matches two mouse genes, one split by speciation and one born by duplication. Which is the safer guide to its job?

    • The duplicated copy, since it is newer
    • Both guide equally in all cases
    • The one split by speciation, the orthologue

  8. A non-coding stretch is identical in human, mouse, and chicken. What should you do?

    • Investigate it; it may regulate something important
    • Ignore it; only coding DNA matters
    • Delete it from the genome at once
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Answer key

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

Same genes, different species, shared jobs W1-mt_eBRge2bLeC-s1

  1. Paralogues · A duplication inside one lineage makes paralogues.
  2. Orthologues · They diverged because the species split.
  3. False · Similarity predicts a function; experiments confirm it.
  4. Mutations there were harmful, so it likely matters · Evolution refusing change is a strong hint of purpose.
  5. Orthologues usually keep the old job; duplicates may wander · Spare copies are free to change, so duplication loosens the link to function.
  6. Some sequences persist for structural reasons; proof needs experiments · Conservation earns attention but never settles the job alone.
  7. The one split by speciation, the orthologue · The orthologue usually kept the ancestral job.
  8. Investigate it; it may regulate something important · Deep conservation in non-coding DNA often marks regulation.
Worksheet · LightMySky