5. Ch5_Oct_26_prelecture_post

5. Ch5_Oct_26_prelecture_post - 10/25/09 Oct. 26th

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Unformatted text preview: 10/25/09 Oct. 26th Short
Cuts
with
Double
Recombinants
 







these
combos
are
thus
parental
 •  We
know
that
double
recombinants
are
the
smallest
class
of
progeny
 •  F1
female
was

vg
pr
b
/
vg+
pr+
b+ •  Smallest
group
was:
 •  13
vg

b

pr+
 •  9
vg+
b+
pr
 •  [email protected] •  progeny
that
show
double
X.O.
 •  [email protected] confi[email protected]dle.
 56
 Linked
genes
 •  Linked
genes


from
now
on
refers
to
genes
that
are
<
50
m.u.
apart
 •  [email protected]/w
2
genes
that
are
farther
apart
by
 summing
up
the
length
of
the
map
intervals
b/w
them
 57
 1 10/25/09 Why
a
deficit
of
crossovers?
 •  Expected
probability
of
X.O.
between
vg
&
pr?
 
=
 •  Expected
probability
of
X.O.
between
pr
&
b?
 

=
 •  Expected
probability
of
double
X.O.
b/w
vg
&
b?
 =
 •  [email protected]/w
vg
&
b?
 =
 58
 Why
a
deficit
of
crossovers?
 3‐point
cross
 8
genotypic
classes
 •  [email protected]@cal
analysis
 •  Presence
of
1
X.O.
in
a
region
chance
of
adjacent
X.O.
 •  INTERFERENCE

 59
 2 10/25/09 Coefficient
of
Coincidence
 Coefficient
of
Coincidence

=
observed
frequency
of
double
recombinants
 

 



















expected
frequency
of
double
recombinants
 •  E.g.,
For
vg,
pr,
&
b:
 •  coefficient
of
coincidence
 •  Interference
=
1
–
coefficient
of
coincidence
 •  Interference
=
1
–
observed
frequency
of
double
recombinants
 
 
 






expected
frequency
of
double
recombinants
 •  E.g.,
Interference
=
 60
 [email protected]: 
 Evidence
from
genome
sequencing 
 100 90 80 70 60 50 40 30 20 10 0 0 5000000 10000000 Chromosome 2 [email protected] 
(m.u.)
 15000000 20000000 25000000 physical
distance
(base
pairs)

 3 10/25/09 [email protected]&
Actual
Chromosomes
 Reasons
for
Discrepancies:
 •  difficult
to
completely
correct
for
double
crossovers,
interference
(mapping
 [email protected])
 •  diff[email protected](e.g.,
suppression
of
 [email protected])
 •  diff[email protected] •  Diff[email protected]/w
the
sexes.
 •  E.g.,
male
Drosophila
 •  E.g.,
Y
chromosome
 62
 [email protected] 
 4 10/25/09 [email protected]: 
 • traits
and
diseases
of
interest
can
be
locali[email protected] • localizing
genes
fi[email protected] [email protected][email protected][email protected] [email protected]/MHJ


x




mhj/mhj


F1

MHJ/mhj
 Parental
classes
 [email protected]ONE
(1)
parent,
who
is
 heterozygous;
other
parent
just
there
as
gamete
donor
to
help
produce
kids.
 • Phenotypes
of
offspring
used
to
infer
the
genotypes
of
various
gametes
 produced
by
1
individual
(or
individual
of
specific
genotype)
 • Easier
than
trying
to
genotype
eachof
the
gametes
 • If
X‐linked
genes
&
looking
at
only
male
progeny,
then
total
#
of
progeny
 ONLY
takes
into
account
the
males.
 5 ...
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This note was uploaded on 01/10/2010 for the course BIOLOGY biol2040 taught by Professor Tamarakelly during the Fall '09 term at York University.

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