BIOL1006 Lecture Notes - Lecture 11: Chromosome, Lucilia Cuprina, Primer Walking
25 May 2018
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Lecture 11: Mapping the genome
Linkage
- Genes
- Only part of chromosome
- Crossing over
- If genes are on the same chromosome, they do not necessarily sort independently
- Gametes produced will be AB and ab
- Having Ab is rare and requires a recombination event
Testcross data when genes are linked
- Shuffles genes up
- Even though we have had a recombination event, the parental one has not been
affected- the recombination fraction can never exceed 50%
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2
o Lucilia cuprina (Australian sheep blowfly)
Lays eggs under tail
Larvae drill into sheep and eat it alive
- Gene causes crooked bristle and white eye are on same chromosome
- Red eyes and straight bristles
- Red eyes and crooked bristles
- White eyes and straight bristles
- White eyes and crooked bristles
Would expect a 1:1:1:1 ratio
It is not a 1:1:1:1 ratio
The parentals are the most common (where we have chromosome from father –
WCR (red eye and straight bristles) and from the mother- white eyes and
crooked bristles- wcr)
wcr
WCr
WwCrcr
Wcr
Wwcrcr
wCr
wwCrcr
wcr
wwcrcr
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
If genes are on the same chromosome, they do not necessarily sort independently. Gametes produced will be ab and ab. Having ab is rare and requires a recombination event. Even though we have had a recombination event, the parental one has not been affected- the recombination fraction can never exceed 50: lucilia cuprina (australian sheep blowfly) Larvae drill into sheep and eat it alive. Gene causes crooked bristle and white eye are on same chromosome. The parentals are the most common (where we have chromosome from father . Wcr (red eye and straight bristles) and from the mother- white eyes and crooked bristles- wcr) The recombinants are white eyes and straight bristles and red eyes and crooked bristles. Can immediately say 2 genes are linked because they are not segregating in the 1:1:1:1 ratio. The map distance will expand the further away the gene is and will contract when the gene is close.
