Genotypes and Phenotypes for Three Corn Traits 1. Gene Symbol Genotype Phenotype
ID: 145955 • Letter: G
Question
Genotypes and Phenotypes for Three Corn Traits
1.
Gene Symbol
Genotype
Phenotype
Anthyocyanin production
Color Production
(Add two more examples
aa R _ cc
Aa Rr CI
Colorless Production
Aleurone Color
Pr
Purple
Pr
Red
Endosperm Color
YY
Yellow
yy
White
Endosperm appearance
Susu
Smooth/starchy
susu
wrinkled
2. Draw a Punnett square showing genotypes of the F1 and F2 generations based on the given P1 genotype.
F1 Generation:
Corn A- “CICI,cc crossed with cici, CC”
CIc
CIc
ciC
CIciCc
CIciCc
ciC
CIciCc
CIciCc
Corn B- “CC,RR crossed with cici, CC”
CR
CR
cr
CRcr
CRcr
cr
CRcr
CRcr
Corn C- “RR, SuSu crossed with rr, susu”
RSu
RSu
rsu
RrSusu
RrSusu
rsu
RrSusu
RrSusu
Corn B
CR
Cr
cR
cr
CR
CRCR
CRCr
CRcR
CRcr
Cr
CRCr
CrCr
CrcR
Crcr
cR
CRcR
CrcR
cRcR
cRcr
cr
CRcr
Crcr
cRcr
crcr
F2 Generation:
Corn A
CIC
CIc
ciC
cic
CIC
CICCIC
CICCIc
CICciC
CICcc
CIc
CICCIc
CIcCIc
CIcciC
CIccic
ciC
CICciC
CIcciC
ciCciC
ciCcic
cic
CICcic
CIccic
ciCcic
ciccic
Corn Ccc
RSu
Rsu
rSu
rsu
RSu
RSuRSu
RSuRsu
RSurSu
RSursu
Rsu
RSuRsu
RsuRsu
RsurSu
Rsursu
rSu
RSurSu
RsurSu
RSurSu
rSursu
rsu
RSursu
Rsursu
rSursu
rsursu
Questions for Section I Answer the Following Questions Below as They Pertain to the Above Genetic Information
1. What makes the kernels for corn A yellow? In other words, why do you see the yellow coloring on this corn? Provide a predicted genotype of the corn, including all genes that involve color (A,R,C,Pr,Y).
2. What alleles need to be dominant to allow the corn to have anthocyanin production?
3. What would be the expected phenotype of corn B if the C and R genes were linked in the P1 generation? (Hint: draw out the chromosomes first.)
4. How would the expected phenotypic ratio change in corn C if the R gene crossed over with the recessive allele in one parent of the F1 generation?
Gene Symbol
Genotype
Phenotype
Anthyocyanin production
Color Production
(Add two more examples
aa R _ cc
Aa Rr CI
Colorless Production
Aleurone Color
Pr
Purple
Pr
Red
Endosperm Color
YY
Yellow
yy
White
Endosperm appearance
Susu
Smooth/starchy
susu
wrinkled
Explanation / Answer
Please find the answers below:
Answer 1: According to the tabulated data and the Punnett square described, it can be clearly deduced that presence of even a single dominant allele Y is capable of making the corn yellow in color. Since the allele is dominant, most of the progeny is yellow in color.
Answer 2: Anthocyanin production in the aleuron seems to be dependent upon recessive alleles, hence presence of homozygous recessive alleles i.e. aarrcc enhances anthocyanin production or red coloration of aleuron.
Answer 3: According to the information, the normal cross results in a 9:3:3:1 phenotype ratio when the genes are not linked to each other. However, if the dominant alleles were linked to each other, no crossing over would have taken place, thus the final phenotype ratio would have been deviated to 13:1.
Answer 4: The information suggests that crossing the corn C with a parent with recessive allele is taking place. This is a classic case of test cross which always yields a phenotype and genotype ratio of 1:1:1:.
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