Biology 433
RFLP Mapping Problem
"top"
1) DNA markers detect co-dominant
RFLPs in Landsberg erecta (Ler)
and Columbia (Col) Arabidopsis
accession lines (see Fig.1 for
CUT1 and BEAU RFLPs).
CER6
centromere
AG
mapped in 2)
CUT1
6% recomb. 6 map units
BEAU
GL2
known at outset to be here
"bottom"
Chromosome 1, Arabidopsis
2) Co-segregation and recombination
frequency in the F2 population
segregating for 2 RFLPs can be
used to map RFLPs relative to
each other (see Fig 2 for example
of mapping data between CUT1 +
BEAU).
3)
As illustrated in the map above, AG (a gene controlling flower development, which has
been cloned – DNA probe available) is more tightly linked to CUT1 than BEAU. Show the
results of an experiment that demonstrates this, building on the data in Fig. 2) [i.e. using the
same DNA blot – you need to invent Ler and Col RFLP phenotypes for Ag and probe the
same blot shown in Fig. 2].
4)
As illustrated in the map above, CER6 (also cloned; DNA probe available) is unlinked to
CUT1 (on a different arm of the same chromosome). Show the results of an experiment that
show this, building on the data in 2) [using the same DNA blot – you need to invent Ler and
Col RFLP phenotypes for CER6].
5)
GL2 is the glaborous2 gene, identified only by leaf hair phenotype. The gene has not been
cloned. G12 mutants are recessive and are easily distinguished from wild-type GL2
because leaves lack trichomes (leaf hairs) and thus appear shiny (glaborous) instead of
fuzzy. To map GL2 relative to CUT1, a mapping population was set up as follows:
gl2 gl2
X
(Ler) ↓
gl2 GL2
X
↓
¼ glaborous
¾ wild-type
GL2 GL2
(Col)
selfed
P
(phenotype)
F2 population
100 individuals
F1
Out of a population of 100 F2 plants, 25 were selected with the g12 phenotype.
Show the results of an experiment using these 25 individuals that shows linkage of the GL2
gene to the CUT1 gene, with a map distance of 8 map units. [you will need to prepare a new
DNA blot for this]
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