Genetics Answers

In a pea plant that breeds true for tall, what possible gametes can be produced? Use the symbol D for tall, d for dwarf.

A. In a pea plant that breeds true for dwarf, what possible gametes will be produced?

B. What will be the genotype of F1 offspring from a cross between these two types?

C. Assuming that the allele for tall is dominant, what will be the phenotype of F1

offspring from a cross between these two types?

E. What will be the probable distribution of traits in the F2 generation? (Illustrate with a Punnett square).

a. In a pea plant that breeds true for tall, what possible gametes can be produced? Use

the symbol D for tall, d for dwarf.

c. What will be the genotype of F1 offspring from a cross between these two types?

d. Assuming that the allele for tall is dominant, what will be the phenotype of F1

offspring from a cross between these two types?

e. What will be the probable distribution of traits in the F2 generation? 

What is the probability that a women carrying an abnormal X-linked gene has three sons are unaffected?

What is the probability that a women carrying an abnormal X-linked gene has two sons unaffected an one affected? 

What is the probability that a women carrying an abnormal X-linked gene has two sons affected an one unaffected? 

What is the probability that a carrier women will transmit an abnormal X-linked gene to her 3 sons?

What is the probability that a carrier women will transmit an abnormal X-linked gene to her son? 

A 31 year old woman consults her physicain because she is concerned about developing breast cancer. She is currently in good health and she has never had any breast disease. Her concern arises bacause her sister has just been diagnosed as having breast cancer and her mother died of breast cancer.

• How can one determine if the cancer in this family is likely to be a dominantly inherited predisposition?
• What is the woman’s cahnce of developing breast cancer?

Assume that two individuals with the same mutation in the BRCA1 gene, two of them are heterozygous and the effect of the mutation is dominant. Heterozygous mutations in the BRCA1 gene have been associated with breast cancer development. However one of the individual developped breast cancer but the othe inidividual survided very healthy life untill she died. How would you explain this situation that expected phenotype is not observed from the given genotype?

A 21 year old women consult her physician because she is concerned about devoloping adult polycystic kidney disease (APKD). She has always been healthy and has never had any problems with her kidneys or urine. Also, her sister is healty. However, her father just developped renal failure, and her aunt and grand mother had renal transplants in their 40s. The women’s father, aunt, and grandmother have been diagnosed as having APKD. The patients’s 28 years old cousin (her aunt daughter) also has been found to have this condition, but she is healthy.

• Draw the pedigree fort his family (Indicate the generation and individual numbers).
• What is the most likely pattern of inheritance for AKPD in this family?
• Indicate the genotypes of the individuals in the family (A: dominat allele, a: recesive alle)
• What is the chance of the patient devoloping APKD?