Question

The recessive traits in garden pea plants are as follows: yellow pods (g) are recessive to green pods (G); bluish-green seedlings (s) are recessive to green seedlings (S); creeper (p) (a plant that cannot stand up) is recessive to normal (P). A homozygous plant with green pods, green seedlings and normal stature was crossed to a creeper with yellow pods and bluish-green seedlings. The F1 plants were then crossed to creepers with yellow pods and bluish-green seedlings. The following results were obtained:

2059 green pods, green seedlings, normal

151 green pods, green seedlings, creeper

281 green pods, bluish-green seedlings, normal

   15 green pods, bluish-green seedlings, creeper

2041 yellow pods, bluish-green seedlings, creeper

157 yellow pods, bluish-green seedlings, normal

282 yellow pods, green seedlings, creeper

      11 yellow pods, green seedlings, normal

A. Complete a Punnett square representing the test cross discussed above . Complete the Punnett square by hand, take a picture and upload it to the folder "SHOW YOUR WORK".

B. Determine the expected genotypic and phenotypic ratio of the test-cross above. Answer B in the space provided below.

C. Calculate the genetic distances among the three genes? . Complete this by hand. Show your work (data grouping, equations, and results), take a picture and upload it to the folder "SHOW YOUR WORK".

D. Construct the genetic map describing the map distances and the order of the genes. . Complete this by hand, take a picture and upload it to the folder "SHOW YOUR WORK" no later than 10 minutes after you had completed your exam.

E. Calculate the expected number of double cross-overs. Provide an answer in the space below. Complete this by hand (equations and results), take a picture and upload it to the folder "SHOW YOUR WORK". 3 marks.

F. Calculate the coefficient of coincidence and provide an answer in the space below. Complete this by hand (equations and results), take a picture and upload it to the folder "SHOW YOUR WORK". 3 marks.

G. Calculate the Interference. What does this number mean? provide the two answers in the space below. Complete this by hand (equations and results), take a picture and upload it to the folder "SHOW YOUR WORK". 3 marks.

In the space below, clearly identify each answer as B, E, F, G.

SHOW WORK

Answer 1

Answer-

According to the given question-

Here we have a pea plant have green pods (G), with green seedlings (S); and are normal (P) which means can stand up on the ground are dominant to other pea plant with yellow pods (g), with bluish-green seedlings (s) and are creeper (p), cannot stand on ground.

When we make a cross between both the homozygous plants we get F1 Generation. Now F1 Generation offspring were test crossed to their recessive parents such as the pea plant with yellow pods (g), with bluish-green seedlings (s) and are creeper (p) then we get following offspring in F2 Generation.

green pods, green seedlings, normal = 2059

green pods, green seedlings, creeper = 151

green pods, bluish-green seedlings, normal = 281

green pods, bluish-green seedlings, creeper= 15

yellow pods, bluish-green seedlings, creeper= 2041

yellow pods, bluish-green seedlings, normal = 157

yellow pods, green seedlings, creeper = 282

yellow pods, green seedlings, normal = 11

We know that when we make a cross between

Parent 1 - GGSSPP * ggsspp Parent 2 , then we get all offspring with Green pods, Green seedlings and are normal with GgSsPp genotype in F1 Generation.

(A) When we make a test cross between F1 Generation offspring and parent 2 we get-

GgSsPp * ggsspp

	gsp	gsp	Gsp	gsp	gsp	gsp	gsp
GSP	GgSsPp (Green pod, Green seedlings, Normal)	GgSsPp (Green pod, Green seedlings, Normal)	GgSsPp (Green pod, Green seedlings, Normal)	GgSsPp (Green pod, Green seedlings, Normal)	GgSsPp (Green pod, Green seedlings, Normal)	GgSsPp (Green pod, Green seedlings, Normal)	GgSsPp (Green pod, Green seedlings, Normal)
GSp	GgSspp (Green pod, Green seedlings, Creeper)	GgSspp (Green pod, Green seedlings, Creeper)	GgSspp (Green pod, Green seedlings, Creeper)	GgSspp (Green pod, Green seedlings, Creeper)	GgSspp (Green pod, Green seedlings, Creeper)	GgSspp (Green pod, Green seedlings, Creeper)	GgSspp (Green pod, Green seedlings, Creeper)
GsP	GgssPp (Green pod, Blue-green seedlings, Normal)	GgssPp (Green pod, Blue-green seedlings, Normal)	GgssPp (Green pod, Blue-green seedlings, Normal)	GgssPp (Green pod, Blue-green seedlings, Normal)	GgssPp (Green pod, Blue-green seedlings, Normal)	GgssPp (Green pod, Blue-green seedlings, Normal)	GgssPp (Green pod, Blue-green seedlings, Normal)
Gsp	Ggsspp (Green pod, Blue-green seedlings,creeper)	Ggsspp (Green pod, Blue-green seedlings,creeper)	Ggsspp (Green pod, Blue-green seedlings,creeper)	Ggsspp (Green pod, Blue-green seedlings,creeper)	Ggsspp (Green pod, Blue-green seedlings,creeper)	Ggsspp (Green pod, Blue-green seedlings,creeper)	Ggsspp (Green pod, Blue-green seedlings,creeper)
gSP	ggSsPp (Yellow pod, Green seedlings, Normal)	ggSsPp (Yellow pod, Green seedlings, Normal)	ggSsPp (Yellow pod, Green seedlings, Normal)	ggSsPp (Yellow pod, Green seedlings, Normal)	ggSsPp (Yellow pod, Green seedlings, Normal)	ggSsPp (Yellow pod, Green seedlings, Normal)	ggSsPp (Yellow pod, Green seedlings, Normal)
gSp	ggSspp (Yellow pod, Green seedlings, Creeper)	ggSspp (Yellow pod, Green seedlings, Creeper)	ggSspp (Yellow pod, Green seedlings, Creeper)	ggSspp (Yellow pod, Green seedlings, Creeper)	ggSspp (Yellow pod, Green seedlings, Creeper)	ggSspp (Yellow pod, Green seedlings, Creeper)	ggSspp (Yellow pod, Green seedlings, Creeper)
gsP	ggssPp (Yellow pod, Blue-Green seedlings, Normal)	ggssPp (Yellow pod, Blue-Green seedlings, Normal)	ggssPp (Yellow pod, Blue-Green seedlings, Normal)	ggssPp (Yellow pod, Blue-Green seedlings, Normal)	ggssPp (Yellow pod, Blue-Green seedlings, Normal)	ggssPp (Yellow pod, Blue-Green seedlings, Normal)	ggssPp (Yellow pod, Blue-Green seedlings, Normal)
gsp	ggsspp (Yellow pods, Blue-green seedlings, Creeper)	ggsspp (Yellow pods, Blue-green seedlings, Creeper)	ggsspp (Yellow pods, Blue-green seedlings, Creeper)	ggsspp (Yellow pods, Blue-green seedlings, Creeper)	ggsspp (Yellow pods, Blue-green seedlings, Creeper)	ggsspp (Yellow pods, Blue-green seedlings, Creeper)	ggsspp (Yellow pods, Blue-green seedlings, Creeper)

(B) We get offspring –

Phenotype - Green pod, Green seedlings, Normal : Green pod, Green seedlings, Creeper : Green pod, Blue-green seedlings, Normal : Green pod, Blue-green seedlings,creeper : Yellow pod, Green seedlings, Normal : Yellow pod, Green seedlings, Creeper : Yellow pod, Blue-Green seedlings, Normal : Yellow pods, Blue-green seedlings, Creeper In the ratio of 1 : 1

Genotype - GgSsPp: GgSspp: GgssPp: Ggsspp : ggSsPp: ggSspp : ggssPp : ggsspp

(C)

Now we have to find the gene present in middle, so arrange the given offspring in decreasing order such as –

green pods, green seedlings, normal = 2059

yellow pods, bluish-green seedlings, creeper = 2041

yellow pods, green seedlings, creeper = 282

green pods, bluish-green seedlings, normal = 281

yellow pods, bluish-green seedlings, normal = 157

green pods, green seedlings, creeper = 151

green pods, bluish-green seedlings, creeper = 15

yellow pods, green seedlings, normal = 11          

Here green pods, green seedlings, normal and yellow pods, bluish-green seedlings, creeper are parental while green pods, bluish-green seedlings, creeper and yellow pods, green seedlings, normal are double cross over.

Total offspring = 4997

Total double cross over = 15 + 11 = 26

Distance between Green seedlings (S) and Green pod (G) = 282 + 281 + 15 + 11 = 589 / 4997 = 0.117 = 0.117 * 100 = 11.7 cM

Distance between S and G = 11.7 cM

Distance between Green pod (G) and Normal (P) = 157 + 151 + 15 + 11 = 334 / 4997 = 0.066 =   0.066 * 100 = 6.6 cM

Distance between G and P = 6.6 cM

(D)

(E)

Expected double crossovers = (frequency of crossing over between S and G )   * (frequency of crossing over between G and P) * number of total offspring

So expected double crossovers = 0.117 * 0.066 * 4997

  Expected double crossovers =  38.58

(F) Coefficient of coincidence = all observed double crossing over / (distance between first two genes) (distance between last two genes) * total number of offspring

= (15 + 11 ) / (0.117) (0.066) * 4997

= 36 / 38.58

Coefficient of coincidence = 0.933

(G) Interference (I) =1- Coefficient of coincidence

= 1- 0.933 = 0.067 or 6.7 %

Interference (I) = 0.067 or 6.7 %