Exploring Genetics
You can use a Punnett square to show the combinations possible for 2 gene traits:
Do genes segregate independantly, or are traits linked in some way?
Round Yellow Peas (RRYY)
Mendel conducted an experiment in which he crossed a true­
breeding plant with round and yellow peas with a true breeding wrinkled green pea plant.
(RRYY) x (rryy)
RY
RY
RY
RY
ry
RrYy
RrYy
RrYy
RrYy
ry
RrYy
RrYy
RrYy
RrYy
ry
RrYy
RrYy
RrYy
RrYy
ry
RrYy
RrYy
RrYy
RrYy
Wrinkled Green peas (rryy)
The F 1 generation produced all plants with round, yellow peas (the dominant characteristics).
Oct 18­1:34 PM
Oct 18­1:41 PM
Summarize your results using the following table:
To determine whether or not these genes segregated indepensantly, he allowed the plants to self­pollinate and create an F
Use a Punnett square to predict the F
2 generation.
Number
2 offspring traits:
Round Yellow peas:
Heterozygous
Round Yellow Peas (RrYy)
RY
Heterozygous
Round yellow peas (RrYy)
Ry
rY
ry
RrYy
Ry RRYy RRyy
RrYy
Rryy
rY RrYY
RrYy
rrYY
rrYy
ry
Rryy
rrYy
Rryy
~19%
3
~19%
wrinkled yellow peas:
1
~6%
Figure 11 ­ 10, p. 271
Oct 18­1:48 PM
Since some of the F
2 offspring does not look like wither parent, Mendel was able to conclude that genes segregate independently.
A monohybrid cross
for a single gene.
( Just because you get one gene, doesn't mean you'll automatically )
get the other one as well.
independant assortment
~56%
Round green peas:
Oct 18­1:39 PM
This principle is known as 9
Wrinkled yellow peas: 3
RY RRYY RRYy RrYY
RrYy
Percentage
is a cross between two heterozygous organisms ex: Heterozygous tall pea plants (Tt x Tt)
.
A dihybrid cross
two genes.
is a cross between two heterozygous organisms for ex: Heterozygous round yellow peas (RrYy x RrYy)
Oct 18­1:57 PM
Oct 18­2:09 PM
1
The rules of genetics we have seen so far do not account for the diversity of traits in all organisms. In some cases, alleles are neither dominant or recessive.
Use your TB to create a working defenition of the following genetic concepts:
­ Incomplete dominance
­ Codominance
­ Multiple alleles
­ Polygenic traits
Use pages 272 ­ 274 to complete this work.
Oct 18­1:53 PM
Oct 18­2:18 PM
Do an inheritance lab (see file!)
http://www.phschool.com/webcodes10/index.cfm?wcprefix=cbp&wcsuffix=4112
&fuseaction=home.gotoWebCode&x=0&y=0
Oct 18­2:09 PM
2