Topic 1 - Recombination And Chromosome Rearrangements Flashcards
What is the basic unit of inheritance?
Chromosome
What is the structure of a chromosome?
End - telomere
Middle - Centromere
One half - chromatid
When does crossing over occur?
During meiosis 1
Why is crossing over important?
1) shuffles genetic variation
2) creates novel genetic variation
What occurs during meiosis 1?
Homologous chromosomes line up at metaphase plate, crossing over occurs between non-sister chromatids. Homologous chromosomes migrate to opposite poles
What occurs during meiosis 2?
Chromosomes line up at metaphase plate and sister chromatids separate. End up with four different genetically unique spores
Between what parts of chromosome does crossing over occur?
Between non-sister chromatids
What are the five basic chromosome rearrangements?
1) inversions
2) translocations
3) Duplications
4) deletions
5) acentric fragments
What is inversion?
Rearrangement within chromosome, pericentric, paracentric
What is symmetric paracentric inversion?
Broken piece flips around and rejoins with rest of the chromosomes, it will be viable
What is asymmetric paracentric inversion?
Broken chromosome fragment rejoins the ends, but the sticky ends of the internal chromosome piece join together without a centromere, an interstitial deletion and acentric ring forms, not viable
What is symmetric pericentric inversion?
Broken pieces on ends flip places on the chromosome, will be viable
What is asymmetric inversion?
Two outside pieces come together, ends of broken chromosome with centromere cone together to form centric ring and acentric fragment, not viable
What is translocation?
Rearrangements involving 1 or more chromosome, reciprocal and robertsonian
What is symmetric reciprocal translocation?
Two chromosomes are cut, ends without centromere go to the opposite chromosome and each chromosome has centromere but with the other chromosomes genes on part of it, will be viable under certain circumstances
