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1) Genes are?.

1. located on chromosomes, inherited in the same way as chromosomes, arranged in linear sequence on chromosomes, may be exchanged between homologous chromosomes.


2) What concept helps to explain why close relatives have a varied mix of genetic traits?

2. independent assortment


3) Describe homologous chromosomes.

3. There are two of each kind, Each parent contributes one of each homologous pair, Most homologous chromosomes carry the same genes for the same traits, Homologous chromosomes pair up during early meiosis


4) DNA coding regions that affect the same trait are called????..

4. alleles


5) The location of a gene on a chromosome is its????????.

5. locus


6) True or False? The closer together genes are found on a chromosome, the greater the chance that crossing over will occur between them.

6. False


7) What is a karyotype?

7. is a visual display of chromosomes arranged according to size.


8) In karyotyping, what distinguishes individual chromosomes from each other?

8. a comparison of chromosome lengths, bands produced on chromosomes by differential staining, the position of centromeres, the relative lengths of the "arms."


9) Karyotyping is usually done using what kind of cells?

9. blood


10) What can Karyotype analysis be used in?

10. prenatal diagnosis to detect chromosomal mutations and genetic disorders in embryos.


11) With respect to chromosomes how is the difference between normal human males and females defined

11. In males, an X is replaced by a Y.


12) Describe sex chromosomes.

12. determine gender, vary from one sex to another, carry some genes that have nothing to do with sex, appear in a diploid cell as either XX or XY


13) True or false, for the sex chromosomes: The Y chromosome carries a greater number of nonsexual traits.

13. False


14) True or false, for the sex chromosomes: X and Y are different in size but carry nearly equal numbers of genes.

14. False


15) True or false, for the sex chromosomes: The X chromosome carries more genes for nonsexual traits.

15. True


16) True or false, for the sex chromosomes: The X chromosome carries only gender-related genes.

16. False


17) In human females, one of the sex chromosomes is switched off during early development. What is this called?

17. X inactivation


18) When does X inactivation occur?

18. after the first cleavages of the zygote


19) What is a condensed, female X chromosome called?

19. Barr body


20) Because geneticists can't use human subjects for experimentation, a ____ is used to obtain an analysis of a genetic family history.

20. pedigree chart


21) Which term could be used to describe a person with one normal gene and one gene for a recessive disease?

21. carrier


22) A carrier is a person who???

22. carries a recessive gene for a genetic disorder but shows no signs or symptoms


23) Chromosomes other than those involved in sex determination are known as

23. autosomes


24) An autosomal recessive disorder ??.

24. can appear only in children of parents who both carry the gene


25) The probability of producing a phenotypically normal child by two parents who are carriers for an autosomal recessive disorder is

25. 75 percent


26) The probability of producing a child who suffers from cystic fibrosis by two parents who are carriers for the autosomal recessive disorder is

26. 25 percent


27) If a study of several pedigrees demonstrated that two parents are normal but their children express a trait, then the trait is controlled by a

27. recessive gene


28) A woman is diagnosed as having the genetic disease known as Huntington's disease. It is a rare defect caused by an autosomal dominant allele. The chance for any one of her eggs to carry the gene is

28. dependent on the genotype of the woman


29) In an autosomal dominant disorder such as Huntington's, two heterozygous parents have the probability of passing the gene on to ____ percent of their children.

29. 75


30) A color-blind man and a woman with normal vision whose father was color blind have a son. Color blindness, in this case, is caused by an X-linked recessive gene. If only the male offspring are considered, the probability that their son is color-blind is

30. 50 percent