Genetics Review

What does the term phenotype mean? Answer: How a trait appears/looks Question #1 What does the term phenotype mean? Answer: How a trait appears/looks

Question #2 What does the term genotype mean? Answer: The group of genes that make up a trait (the letters)

Question #3 What does a capital letter mean? Answer: It means the allele is dominant

(aa-one from mom and one from dad) Question #4 If an allele is recessive how many copies of the allele are needed for it to be expressed? Answer: Two copies (aa-one from mom and one from dad)

What type of alleles are known as ‘loud and bossy’? Question #5 What type of alleles are known as ‘loud and bossy’? Answer: Dominant alleles

Complete Dominance

Question #6 Purple flowers (P) are dominant to white flowers. Write the genotype of a heterozygous purple flower. Answer: Pp

Question #7 Purple flowers (P) are dominant to white flowers. If a white flower is crossed with a heterozygous purple flower, what is the chance of having white flowers? Answer: 50% Pp pp p P

Question #8 Purple flowers (P) are dominant to white flowers. If two heterozygous flowers are crossed, what is the chance of having white flowers? Answer: 25% PP Pp pp p P

Is AA, heterozygous, homozygous dominant or homozygous recessive? Question #9 Is AA, heterozygous, homozygous dominant or homozygous recessive? Answer: homozygous dominant

Question #10 If red colored dragons are dominant to orange colored dragons what is the phenotype for a dragon who is Rr? Answer: Red

Question #11 If red colored dragons are dominant to orange colored dragons what is the genotype for a dragon who is orange (use R)? Answer: rr

What is another name for homozygous? Answer: Purebred Question #12 What is another name for homozygous? Answer: Purebred

What is another name for hybrid? Answer: Heterozygous Question #13 What is another name for hybrid? Answer: Heterozygous

Question #14 In Oompa Loompahs, gray faces (G) are dominant to orange. If a homozygous gray faced male married a heterozygous gray female and they have 6 kids, about how many will have gray faces? Answer: All 6 GG Gg g G

Question #15 Two heterozygous Oompahs are crossed. What proportion of the offspring will have orange faces? Answer: 25% GG Gg gg g G

Incomplete Dominance

Question #16 In a certain type of fish there are three possible alleles; red, orange, and yellow. Orange is the intermediate of red and orange. Assuming red is R and yellow is Y, what is the genotype for the orange fish? Answer: RY

In these same fish where Question #17 In these same fish where RR- Red, RY- Orange, and YY- Yellow, what are all of the possible phenotypes of an orange fish is mated with a yellow fish? Answer: orange and yellow RY YY Y R

In these same fish where Question #18 In these same fish where RR- Red, RY- Orange, and YY- Yellow, what are all of the possible genotypes if two orange fish are mated? Answer: RR, RY, YY RR RY YY Y R

In these same fish where Question #19 In these same fish where RR- Red, RY- Orange, and YY- Yellow, what are the chances of having yellow fish if a red fish is mated with a yellow fish? Answer: 0%, all would be orange RY Y R

Question #20 Answer: 50% chance R is red and W is white in 4 o’clocks. If a pink flower is crossed with a red flower what are the chances of getting red flowers? Answer: 50% chance RR RW R W

Codominance

Question #21 Answer: 25% chance In heffalumps, pink (P) and yellow (Y) are equally dominant, the heterozygote is spotted. If two spotted heffalumps are mated, what are the chances of getting the yellow gene? Answer: 25% chance PP PY YY Y P

Question #22 Answer: 0% chance In heffalumps, pink (P) and yellow (Y) are equally dominant, the heterozygote is spotted. If a pink heffalump is mated with a spotted heffalump, what are the changes of getting the yellow gene? Answer: 0% chance PP PY P Y

Red- ____ White- ____ Roan- __ Question #23 In some cattle the color roan is a mixture of red (R) and white (W)? What are the genotypes for the following colors: Red- ____ White- ____ Roan- __ Answer: RR, WW, RW

Question #24 In some cattle the color roan is a mixture of red (R) and white (W)? If a red cow and a white bull are mated, what are the chances of having roan babies? Answer: 100% RW W R

Multiple Alleles

Question #25 In humans, blood type is a classic example of a trait inherited by multiple alleles. What does multiple alleles mean? Answer: There are more than two alleles for a trait (within a population).

Question #26 In humans, blood type is a classic example of a trait inherited by multiple alleles. How many different alleles are there? Answer: 3

Question #27 Answer: A, B, and O In humans, blood type is a classic example of a trait inherited by multiple alleles. What are the three alleles possible? Answer: A, B, and O

Question #28 Answer: 2, one from mom and one from dad In humans, blood type is a classic example of a trait inherited by multiple alleles. How many alleles does each person receive? Answer: 2, one from mom and one from dad

Question #29 Answer: A and B Complete the following: Blood Types ____ and ____ are dominant over Type O Answer: A and B

Complete the following: Question #30 Complete the following: Blood Types ____ and ____ are codominantly expressed, meaning they are expressed together Answer: A and B

What blood type is known as the universal donor and why? Question #31 What blood type is known as the universal donor and why? Answer: Type O blood, because it has no antigens on its surface and therefore can be given to any person

What blood type is known as the universal receiver and why? Question #32 What blood type is known as the universal receiver and why? Answer: Type AB blood, because it will not react poorly to antigen A or B and a person with this blood type can receive a tranfusion from anyone

Question #33 If a mother is homozygous for type A blood and a father is heterozygous for type B blood, what are the chances of having a child with type O blood? Answer: 0% AB AO O B A

Question #34 If a mother has type B blood and her son has type O blood is the mother homozygous B or heterozygous B? Answer: Heterozygous, because he had to get one O from dad and one O from mom

Question #35 A woman and her husband claim that their child was mixed up on the hospital because of its dark hair. The mother has type B blood and the father has type A blood. The alleged child has type O blood. Should the parents be concerned? Answer: No, the mom and dad could both be heterozygous resulting in a child with type O blood.

Question #36 1. A nonhemophiliac man marries a nonhemophiliac woman whose father was a hemophiliac. What kinds of children can they have and in what percentages?

Question #36 Sex –Linked Genetics Step 1: Determine the letters you will use to represent the alleles. For this one I chose “B” for normal blood and “b” for the hemophiliac gene. Step 2: Determine the alleles of the parents. The non-hemophiliac man must be XBY. The non-hemophiliac woman with a hemophiliac father must be XBXb, because she had to get Xb from her afflicted father. Step 3: Set up your Punnett square and do the cross. Determine the genotypes and expected percent of each type of child from the cross. Sex –Linked Genetics

Question #36 XB XB XB Y XBXb Xb Y XB Y XB Xb 25% Normal girl 25% Normal boy 25% Carrier girl 25% Hemophiliac son XB XB XB XB Y Xb XBXb Xb Y

Question #37 Two normal-visioned parents have a color-blind son. What are the genes of the parents? What are the chances of their having a color blind girl? Explain.

Question #37 Step 1 : Choose your alleles. I will use “C” for normal color vision and “c” for the red/green color blind condition. Step 2 : Determine the genotypes of the parents. Both parents have normal vision, yet they have a color-blind son. Because, the dad can not have the “c” allele (it’s sex-linked remember and he has normal vision) the wife must be a carrier. Dad = XCY and Wife= XCXc Step 3 : Set up your Punnett square and do the cross!

XC Y XC Xc XCXC XCY XCXc XcY There are no chances of this couple having a color blind girl. The father would have to be color blind to contribute the second defective Xc allele needed to produce a color-blind daughter.

Question #38 A normal-visioned man marries a normal-visioned woman whose father was color-blind. They have two daughters who grow up and marry. The first daughter has five sons, all normal-visioned. The second daughter has two normal-visioned daughters and a color-blind son. Diagram the family tree, including the genes of all the people mentioned.

Question #38 Step 1 : As this is another problem about color blindness, we already have our alleles ready from the previous problem. “C” for normal vision, “c” for the red/green color blind condition. Use what you know from the problem to assign genotypes and do Punnett square crosses to help answer all the questions. A family pedigree might be a great way to show clearly the genes of all the people mentioned. Step 2 : Figure out the genotypes of the parents. Both have normal vision, so the man must be XCY . The woman’s father was color blind she has at least one daughter who has a color blind son. That son had to get his Xc from his mom who had to get it from her mom. So, the woman must be a carrier. (XCXc) Step 3 : Do the crosses. Explain the expected genotypes of all the people involved.

XC Y XC Xc XCXC XCY XcY XCXc Xc Y XC XC Grandpa Dad XCXc XCY XCXc XCY Mom These are their possible offspring. Mom’s dad was color blind, so she got her Xc from him. (see cross above) The problem says they had two daughters, so we will focus on them. One daughter had 5 sons, all with normal vision. She must not be the carrier daughter, otherwise odds are she would have had a color-blind son. Do we know if her husband is color blind or not? The other daughter had 2 normal vision daughters and 1 color-blind son, so she must be a carrier of the Xc allele.

The first daughter would have the genotype, XCXC and all her sons would be XCY and they would have normal vision. If her husband was color- blind it would only effect their daughters, (50% would be expected to be color-blind) but, because they had no daughters we have no way of knowing from this information if he is color-blind or not. (see grandpa to see a Punnett square for this situation.) The second daughter would have to be the carrier. Her daughters have normal vision. However, one or both of them could be carriers of the trait. The son, however, was not so lucky and got the defective X. With no second X to mask the effects, he will be color-blind. XC Y XC Normal vision Normal vision Xc Color-blind son Carrier