Using the gene symbols given above, choose the genotypes of F2 plants. hree domi

ID: 34323 • Letter: U

Question

Using the gene symbols given above, choose the genotypes of F2 plants.

hree dominant traits of corn seedlings, tunicate seed (T -), glossy appearance (G -), and liguled stem (L -), are studied along with their recessive counterparts, nontunicate (tt), nonglossy (gg), and liguleless (ll). A trihybrid plant with the three dominant traits is crossed to a nontunicate, nonglossy, liguleless plant. Kernels on ears of progeny plants are scored for the traits, with the following results:

Using the gene symbols given above, choose the genotypes of F2 plants.

Sort the items below into the following categories: (1) TG/tgLl, (2) TG/tgll, (3) Tg/tgLl, (4) Tg/tgll, (5) tG/tgLl, (6) tG/tgll, (7) tg/tgLl, (8) tg/tgll.

A) Tunicate, nonglossy, liguled

B) Nontunicate, glossy, liguled

C) Nontunicate, glossy, liguless

D) Nontunicate, nonglossy, liguleless

E) Tunicate, glossy, liguled

F) Nontunicate, nonglossy, liguled

G) Tunicate, nonglossy, liguleless

H) Tunicate, glossy, liguleless

part 2. --->

Calculate the recombination frequency between the linked genes from the data presented.

Phenotype Number Tunicate, glossy, liguled 102 Tunicate, glossy, liguleless 106 Tunicate, nonglossy, liguled 18 Tunicate, nonglossy, liguleless 20 Nontunicate, glossy, liguled 22 Nontunicate, glossy, liguleless 23 Nontunicate, nonglossy, liguled 99 Nontunicate, nonglossy, liguleless 110 500

Explanation / Answer

Phenotype

genotype

Number

Tunicate, glossy, liguled

TtGgLl

102

Tunicate, glossy, liguleless

TtGgll

106

Tunicate, nonglossy, liguled

TtggLl

Tunicate, nonglossy, liguleless

Ttggll

Nontunicate, glossy, liguled

ttGgLl

Nontunicate, glossy, liguleless

ttGgll

Nontunicate, nonglossy, liguled

ttggLl

Nontunicate, nonglossy, liguleless

ttggll

110

500

Recombinant between T and G

= 18+20+22+23= 83

Recombinant frequency = 83/500 = 16.6%, so distance between them would be 16.6 map unit

Recombinant between G and L

= 106+18+ 23+99 = 246

Recombinant frequency = 246/500 = 49.2%, so distance between them would be 49.2 map unit

Recombinant between T and L

= 106+20+22+99 = 247

Recombinant frequency = 247/500 = 49.4%, so distance between them would be 49.4 map unit