PART 1:  Know and be able to apply these terms:  Gene, Allele, Genotype, Phenotype, Homozygous, Heterozygous, Dominant, Recessive, Carrier, Hybrid, Incomplete Dominance, Codominance, Sex-linked

 

PUNNETT SQUARES and INHERITANCE: Read all parts of the questions carefully first! 

 

  1. You have two groups of pea plants, one that always produces purple flowers and one that always produces white flowers. There are two alleles for the gene “flower color”. The allele for purple is P (upper-case, dominant) and the allele for white is p (lower-case, recessive). What are the genotypes of the two plant groups?  Please use complete terms (words)
  2. Purple-flowered plants: Heterozygous Dominant

 

  1. White-flowered plants: Homozygous Recessive

 

  1. Fill in the Punnett Square crossing one true-breeding purple and one true-breeding white flowered plant (these are the Parental generation). Click in each square to enter information.

 

 

 

 

 

 

P

 

p

 

P

 

PP

 

Pp

 

 

p

 

Pp

 

pp

 

 

 

 

 

 

 

 

 

 

 

 

  1. Next, fill in the Punnett Square below by mating one of the offspring above (F1 generation) with a true-breeding white-flowered pea plant. (question continues page 2)

 

 

 

 

 

P

 

p

 

P

 

PP

 

Pp

 

 

p

 

Pp

 

pp

 

 

 

 

 

 

 

 

 

 

 

  1. What are the possible genotypes of this F2 generation? 8/18

 

  1. What are the phenotypes of the F2 generation?

 

 

  1. Having polydactyly (more than 5 fingers per hand) can be caused by many different factors, some developmental but some are genetic. In one case, it can be due to a dominant allele. You read that correctly! Remember the proportion of different types of alleles in any population is not linked to whether alleles are dominant or recessive.

 

  1. If someone has the normal number of fingers (their phenotype is “normal), what are all of the possible genotypes? This does not require a Punnett square! Use P (for polydactyly) and p (for the normal number of fingers) to symbolize the two possible alleles of this trait.

 

 

  1. If someone has polydactyly (their phenotype is “extra fingers”), what are all of their possible genotypes?

 

  1. Could a person with five fingers and toes on their hands have parents who both had extra fingers? Please describe.

 

 

  1. The Manx cat is a hybrid, known for a very short or no tail. This is due to an incomplete but highly penetrant dominant trait (T for tail-less).
  • A Manx cat has one tail-less (T) and one normal (t) allele
  • Cats who are homozygous recessive (tt) will have normal, long tails
  • The homozygous dominant condition (TT) is lethal—the embryo will not develop properly (no spine develops at all, or spina bifida occurs—i.e., no cat!).

a). If two Manx cats breed, what are the chances of Manx offspring, kittens with tails, or the lethal condition?  Fill out the Punnett square: and write out the resulting phenotype outcomes: (question continued next page).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

b). What are the resulting phenotype outcomes from this cross?

 

 

c.) What genotype of parent cats would you need to breed together to produce more Manx cats but not have any lethal outcomes?

 

  1. This question involves the ABO blood type. There are three possible alleles, two of which are codominant. The blood type is the phenotype (A, B, AB or O)—this is how your blood acts when other blood is added to it.  The genotype consists of two alleles out of three possible alleles.  The alleles IA and IB are codominant, while i (for type O) is recessive to both.

 

We start off with some of the phenotypes and no genotypes.  One parent has Type A blood, the other parent has an unknown blood type. Their children have the blood types shown below. What is the phenotype of the other parent?

What are the genotypes of all five people in this family?

Hint:  This is ultimately a logic problem.  You can start by thinking about the possible genotypes for each phenotype, then it’s a process of elimination.  Start with what you know!

 

Family Member

Phenotype

(blood type)

Genotype

(while some phenotypes may have more than one genotype, there is only ONE correct answer here)

Parent A  
Parent ??                ??  
Child A  
Child B  
Child O  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PART 2: 

Provide the answers to the following Exercises from Lab Manual Chapter 3.  You can type up your answers in a table or attach an image of the completed worksheet.

 

Exercise 4: Interpreting Pedigree Diagrams (P. 71).  Provide all answers (Persons A-G, genotype(s) and phenotype).  Understand that in some cases you may not be able to determine the exact genotype, but you should be able to narrow it down in most cases.  You do NOT need to answer the questions at the end.

 

 

Punnett Squares