Genetics

1. What chromosomal disorder is caused by a piece being lost?

• Deletion

2. What chromosomal disorder is caused by an extra piece of chromosome being added?

• insertion

3. What chromosomal disorder is caused by a piece breaking off & reattaching in the opposite order?

• inversion

4. What chromosomal disorder is caused by part of a chromosome

breaking off and attaching to another chromosome?

• translocation

5. What chromosomal disorder is caused when a chromosome does

not separate?

• nondisjunction

6. In what phases can nondisjunction occur and what is the result for the gametes?• Anaphase I

• Anaphase II

7. Make a dihybrid cross for the following: TtRr TTrr (T=tall;

t=short; R=red; & r=white)• TR Tr tR tr

• Tr TTRr TTrr TtRr Ttrr

• Tr TTRr TTrr TtRr Ttrr

• Tr TTRr TTrr TtRr Ttrr

• Tr TTRr TTrr TtRr Ttrr

8. From the above dihybrid, how many tall red flowers were produced?

• 8-TTRr & TtRr=Tall & Red• 8-TTrr & Ttrr= Tall & White• Equal 16 squares

• TR Tr tR tr

• Tr TTRr TTrr TtRr Ttrr

• Tr TTRr TTrr TtRr Ttrr

• Tr TTRr TTrr TtRr Ttrr

• Tr TTRr TTrr TtRr Ttrr

Tall/Red Tall/White Tall/Red Tall/White

Tall/Red Tall/White Tall/Red Tall/White

Tall/Red Tall/White Tall/Red Tall/White

Tall/Red Tall/White Tall/Red Tall/White

9. What chromosomes are involved with autosomal

conditions?• Pairs #1-22 (all but the sex chromosomes)

10. A hypothetical disorder's location is written as 13q31.5. Answer the following questions using this information.What chromosome is the disorder located?

• 13

10. cont. Is the disorder above or below the centromere?

If it said "p" instead of "q", would it be above or below the centromere?

31.5 represents what?

• Below

• Above

• Units above orbelow the centromere

11. Answer the following questions for Down's Syndrome:List the 4 main characteristics-

It affects what 3 systems the most?

Which chromosome does it affect and what is the cause?

• Mental retardation, muscle weakness, heart defects & short stature

• Brain/neurological, heart/circulatory and muscle

• Chromosome 21 nondisjuntion causing trisomy 21

12.Answer the following questions for Cystic Fibrosis:What 2 systems does it affect?

Which chromosome and what type of autosomal disorder is it?

• Lungs & digestive

• #7 autosomal recessive

13. Answer the following questions for Sickle Cell Anemia:Describe the condition-

What type of autosomal disorder and which chromosome?

• Red blood cells are crescent shaped instead of round. This shape change does not allow them to bind to oxygen properly

• Autosomal recessive chromosome #11

14. Answer the following questions for Huntington's Disease:Describe the condition-

What type of autosomal disorder-

• Deterioration of brain tissue in middle age (30’s & 40’s)

• Chromosome #4 Autosomal Dominant

15. If an offspring has an autosomal dominant disorder, what does that tell you about their parent?

• 1 or both parents have the disorder

16. If both parents are heterozygous with an autosomal dominant disorder (they have the disorder), what is the likeliness for their offspring to have the disorder? (D=disorder & d=no disorder)

D d

D DD Dd

d Dd dd

75% with Disorder

Disorder Disorder

Disorder no disorder

17. What is the likeliness for an offspring to get an autosomal recessive disorder if both parents have the disorder? (d=disorder & D=no disorder)

d d

d dd dd (disorder) (disorder)

d dd dd (disorder) (disorder)

100% disorder

18. If both parents are carriers for an autosomal recessive disorder (they do not demonstrate the condition), what is the likeliness of the offspring

getting the condition. What about the likeliness of being a carrier? (d=disorder & D=no disorder)

D d

D DD Dd

d Dd dd

no disorder carrier

carrier disorder

Disorder =1/4 or 25%

Carrier= ½ or 50%

19. How can an autosomal recessive condition be hidden for generations? • The dominant allele hides it

20. What chromosome number do sex-linked chromosomes occur on?• Pair #23

21. Which chromosome do most sex-linked conditions occur and

why?• X• Larger & carries more genes

22. What type of chromosome does mothers give their offspring? Their fathers?• Mother gives only “X’s” to their offspring• Fathers give X’s to daughters & Y’s to sons

23. Who determines the offspring's sex?

• Father

24. Answer the following about Colorblindness:Description-

Who is most commonly affected-

Type of sex-linked disorder-

• Can’t distinguish certain colors

• Males

• X-linked recessive

25. Answer the following about Hemophilia:Description-

Who is most commonly affected-

Type of sex-linked disorder-

• Blood does not clot

• Males

• X linked recessive

26. Answer the following about Turner Syndrome:Description-

Who is most commonly affected & chromosome combination-What type of sex-linked disorder-

• Females short in stature, no puberty, or menstruation

• Females

• X0-only 1 chromosome• Nondisjunction

27. Answer the following about Klinefelter's Syndrome:Description-What type of sex-linked disorder & chromosome combination-

• Hermaphroditic male & female reproductive organs but only 1 functional

• Nondisjunction-XXY(usually)

28. Who is more affected by X-linked recessive disorders and why?

• Males because they only have 1 X-sex chromosome & girls have a 2nd X which if dominant can mask the disorder

29. If a mother has a disorder, what is the likeliness her son will have it too?• 100%-mother gives the son his only X & if

she only has affected X’s-then he will have disorder

30. If a daughter has a disorder, which parent(s) contributed the

chromosome?

• Both

31. Describe the 3 types of genetic screening and the method used to analyze them?

1. Blood tests

2. Amniocentesis-draw fluid from sac

3. Chorionic Villi Sampling-testing tissue from between uterus & placenta

4. Karyotyping-taking tests & arranging the chromosomes into homologous pairs by size & shape

32. What is the benefit of pedigree charts?

• To view heredity and characteristics

33. What type of allele can a carrier have but not show the

condition?• recessive

34. What type of chromosomal disorder can males not be a recessive carrier for?• X linked