http://www.zerobio.com/drag_gr11/pedigree/pedigree_overview.htm
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Overview
Solve each problem by building the pedigree and answering the questions. Drag the images representing
males, females and genotypes into position on the pedigree tree. Left-click on an image and hold to drag it.
Use the "Check Pedigree" and "Check Answer" buttons only AFTER you have attempted to solve the problem
and built the pedigree. The first two genetic problems allow you to see the correct pedigree but for the last two
problems you are on your own. Good luck!
For entering percent answers, do not include the percent sign or any spaces, just the numbers (ie.75). For
entering word answers, use all small letters (ie. yes). For entering crosses, use capital and small letters for
dominant and recessive genes and leave a space before and after the "x" sign. You can use a "dash" for
unknown genes (ie. T- x Tt). For entering blood types, use capital letters for dominant genes and include the "I"
(ie. IBIB and IAIB). Note the small letter "i" for the recessive gene (ie. IAi and ii). Do not use the word "Type" in
your answer and don't worry about superscripts.
Tongue Rolling
You know that you want to! Go ahead, see if you can.The ability to roll your tongue is caused by a dominant
gene (R). If you can't roll your tongue, you are a non-roller and must be homozygous recessive (rr).
A father cannot roll his tongue but a mother can. Of their four children, one daughter cannot roll her tongue.
The other daughter and both sons can roll their tongues.
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What percent of the offspring are homozygous non-rollers?
What percent of the offspring are heterozygous rollers?
Can the parents produce a homozygous dominant child?
How could the cross for the parents (father x mother) be written using the "dash" technique for
unknown genes?
Eye Color
The color of your eyes us caused by pigment molecules in the iris, the ring that surrounds the black pupil in the
center.While eye color is actually more complicated than this, dark eyes(such as brown or black) is
dominant(E) and light eyes(such as blue or grey) is recessive(e).
A father and a mother both have brown eyes. Their two sons have blue eyes and their two daughters have
brown eyes. One daughter carries the gene for blue eyes, the other doesn't.
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Type the cross for the parents (father x mother).
Is the mother homozygous or heterozygous?
What percent of the children are homozygous recessives?
If one son gets married and all his children have brown eyes, what must the genotype of his wife be?
How could the cross of parents (mother X father) be written with a “dash” technique for unknown
genes?
Diabetes
Diabetes is a disorder of the pancreas in which insulin cannot be produced or is not effective. As a result, blood
sugar cannot be properly controlled. Diabetes have a homozygous recessive genotype(dd).
A father carries the recessive gene for diabetes and a mother does not (generation 1). They have two children
(generation 2), a daughter and a son. The daughter does not suffer from diabetes and marries a man who
does not carry the gene for diabetes. They have one child, a girl who is a carrier (generation 3). The son
marries a diabetic woman and they have two boys, both who suffer from diabetes (generation 3).
10. Can the parents is generation 1 produce a child with diabetes?
11. How many individuals in the entire generation 2 suffer from diabetes (1, 2, 3 or 4)?
12. If you only knew that the girl in generation 3 didn't suffer from diabetes, what is the best way to write
her genotype?
13. What genotype must the boys in generation 3 marry so their children do not suffer from diabetes?
Blood Type
Red blood cells have many types of molecules sticking out of their cell membranes. Some of these are
glycoproteins that determine your blood type. The genes that code for these glycoproteins exhibit something
called “co-dominance” where IA and IB are both equally dominant but O is still recessive. The genotype for
blood type A is written as IAIA or IAi(where “I” is recessive). Blood type B is IBIB or IBi and blood type O is ii.
But put IA and IB together and you get another blood type, AB, the co-dominant type, where neither the A or B
is recessive to the other.
A father has blood type A and a mother has blood type AB. They have 3 children, a son with blood type A,
another son with blood type AB, and a daughter with blood type B. The daughter then marries a man with
blood type O and they have a daughter with type O.
14. Type the cross for the parents (father x mother) in generation 1.
15. What blood type can the parents in generation 1 not produce?
16. What is the best way to write the genotype of the son with type A blood in generation 2?
17. What other blood type can be produced in generation 3?
18. Could the husband of the daughter in generation 2 have blood type B and still produce a type O child?