1. Complex Patterns of Inheritance
Genetics 2
Complex Patterns of Inheritance

2. * *Think of the “y” in boy
How is sex determined?
In humans, the specific chromosomes that control the inheritance of sex characteristics are named the ____ and ___ chromosomes.
Both genders have two sex chromosomes: Female have ____ and males have ____. X Y XX XY
* *Think of the “y” in boy

3. Are you colorblind?
What number do you see?

4. Are you colorblind?
What number do you see?

5. Are you colorblind?
What number do you see?

6. Why are more males colorblind than females?
Genes which are located on the sex chromosomes are said to be sex-_______.
Not all genes on the sex chromosomes control gender (i.e. color-blindness and hemophilia)
linked
Colorblindness is a sex-linked trait. The gene that controls it is located on the X chromosomes

7. Why are some traits more common in men than women?
Sex-linked traits occur more frequently in _________because they have only ______ X chromosome.
If disorders are recessive, a female needs 2 copies of it to get the disorder while men only need 1. They don’t have a second allele to “mask” the recessive one.
men 1

8. How are sex-linked traits inherited?
Color-blindness
____________________ (Xn) is a very common sex-linked trait and is recessive to normal vision (XN). More males have this disorder than females.
XNXN =
XNXn =
XnXn =
XNY =
XnY =
Normal Female
Carrier Female
Color-blind Female
Normal Male
Color-blind Male

9. How is color-blindness inherited?
Cross a carrier female for colorblindness with a male that is normal for colorblindness.
What are the genotypes of the parents? _______X______
XNXn
XnY
XN Xn
What is the probability that one of their children will be colorblind? __________ Xn Y
XNXn
XnXn
50% (2/4)
What is the probability of a son being colorblind? _____________
XNY
XnY
50% (1/2)

10. How is color-blindness inherited?
Cross a normal female and a colorblind male. What is the probability that their daughter will be a carrier?
XN XN
100% (2/2) Xn Y
XNXn
XNXn
XNY
XNY

11. What is your blood type? Do you know what your blood type is?
How many possible blood types are there?

12. Are there only 2 alleles for each trait? Pg.8
Multiple Alleles - A gene that has more than ________ alleles (or forms of a gene). In other words, not just one dominant and one recessive allele (i.e. R and r).
Even though there may be three or more different alleles – remember that each person can only carry two alleles for each gene (or trait). 2

13. How is blood type determined?
In human blood groups, there are three different alleles that determine the basic blood type. Type A and Type B (which are codominant) and Type O (which is recessive).
Your blood type is determined by which two alleles you inherit from your mom and your dad. These alleles tell your body what type of antigen to produce on your red blood cells (RBCs).

14. How is blood type determined?
Antigens are molecules on the blood cells that are recognized by the immune system.
Blood type __ has only A antigens on their RBCs.
Blood type __ has only B antigens
Blood type ___ has both A and B antigens
Blood type __ does not have either A or B antigens. A B AB O

15. How is blood type written?
The following are symbols that are used for blood types:
Blood Type (Phenotype)
Genotype(s)
Type __ ii
IA IA or IA i
IB IB or IB i
IA IB O A B AB

16. How is blood type inherited?
Practice: Only the genotypes & phenotypes that appear in the punnett squares need to be written.
1. A man with type O blood marries a woman with type AB blood, what are the possible blood types of their children?
Possible genotypes of offspring:
i i
IA i: 2/4
IB i: 2/4 IA IB
IA i
Possible phenotypes of offspring:
IB i
Type A= 2/4
Type B= 2/4

17. More Practice pg. 9 YES it’s possible IA i IB i IA IB IB i IA i ii
Is it possible for a man with type A blood and a woman with type B blood to have one child with type O blood and another child with type AB Blood? Why or why not? Show your work!!!
IA i IB i
YES it’s possible
IA IB
IB i
IA i ii

18. Why does knowing your blood type matter?
Sometimes when individuals lose too much blood due to a trauma or surgery, other blood can be given back to them. This is called a ________________ .
transfusion

19. Why does knowing your blood type matter?
antigen
Due to the presence of the _________ on the red blood cells, it is extremely important that the correct blood type be given.
If unidentified antigens are present on a cell, _____________ will attach to the antigens & the __________ system will attack the foreign cell.
If the wrong blood is transfused, the antibodies will cause the blood to clump up, causing the individual to go into shock and possibly die.
antibodies
immune

20. Why does knowing your blood type matter?
universal donor
Type O is known as the __________________. Since there are no antigens on the blood cells it can be given to someone with type A, B, AB or O.
Type AB is called the ____________________. A person with type AB blood could receive a transfusion of blood from any of the four blood types since its body would recognize both the A and B antigens.
universal recipient

21. Do you know your blood type? Are you positive?
You may have heard blood type described as positive or negative. Why?
Red blood cells may also have a second antigen called _______________. This trait is not caused by multiple alleles like the ABO blood groups, rather it is influence by simple complete dominance.
Rh Factor

22. Do you know your blood type? Are you positive?
Rh ___________ allele causes people to produce the Rh antigen on their blood cells. (Dominant)
Rh ____________ allele DOES NOT provide the instructions for making a Rh antigen on the blood cells. (Recessive)
negative
A person that is AB+ has three antigens on their blood cells (A, B and Rh+).

23. How can we tell if someone has a genetic disorder?
Some disorders are caused by specific genes, other disorders are caused by a mess-up in the number of your full chromosomes.
When we are looking at those types of disorders we can use a tool called a karyotype.
Karyotype – a picture/chart of chromosome pairs.

24. What do normal karyotypes look like?
Normal Male Karyotype
Normal Female Karyotype

25. What are some ways that chromosomes can be messed up?
Aneuploidy: having an abnormal number of chromosomes.
ex. Instead of having 46, you have 47 chromosomes.
Trisomy: having 3 of a chromosome instead of 2

26. What are common examples of trisomy?
Down Syndrome
Trisomy 21
Occurs when individuals have 3 copies of chromosome 21 instead of 2
About 1 out of 800 people have this in the US
Symptoms:
Mental retardation
Short, stocky arms and legs
Characteristic facial features

27. What are common examples of trisomy?
Klinefelters Syndrome
Occurs when males have more than one X chromosome
Instead of being XY, this male would be XXY or XXXY
About 1 out of 500 people have this in the US
Symptoms:
Learning disabilities
Infertility
Slight breast development

28. What are some ways that chromosomes can get messed up?
Aneuploidy: having an abnormal number of chromosomes.
ex. Instead of having 46, you have 47 chromosomes.
Monosomy: having 1 of a chromosome instead of 2

29. What is a common example of monosomy?
Turner Syndrome
Occurs when females only get 1 X
About 1 out of 2,500 people have this in the US
Symptoms:
Short stature
Infertility

30. YES! It is called amniocentesis.
Is there a way to find out if a baby will have a genetic disorder before it is born?
YES! It is called amniocentesis.
Amniocentesis is a procedure used to determine if a fetus has a genetic disorder. In this procedure, a large needle is inserted into the abdomen of the mother and a sample of the amniotic fluid is taken. The cells of the fetus can be analyzed for any genetic disorders. One way to analyze the fetal cells is using a karyotype.