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GRE Chromosomal And Molecular Basis Of Inheritance

Subjects : gre, science, biology
Instructions:
  • Answer 50 questions in 15 minutes.
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  • Match each statement with the correct term.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. Alleles of genes on nonhomologous chromosome assort independently during gamete formation.






2. A type of change in chromosome structure as a result of some sort of chromosomal breakage. Occurs when a chromosomal fragment breaks and joins a nonhomologous chromosome.






3. A way of expressing distances between genes - defining one map unit as equivalent to a 1% recombination frequency.






4. Genes located on the same chromosome that tend to be inherited together in genetic crosses. These results deviate from those expected from Mendel'S law of independent assortment.






5. Occurs when a mismatched nucleotide evades proofreading by DNA polymerase or arise after DNA synthesis is completed.






6. Each nucleotide (monomer) consists of a hydrophobic nitrogenous base (T - A - C - or G) - the sugar dioxyribose - and a phosphate group. The phosphate of one nucleotide is attached to the sugar of the next - making up the 'backbone' of alternating ph






7. The strand of DNA that is added on to the template strand one at a time as the fork progresses--with the DNA polymerase nestled in the replication fork. Moves in the 5' to 3' direction.






8. The sex-determining region of Y. The gene on the Y chromosome required for the development of testes. In the absence of SRY - the gonads develop into ovaries. SRY is simply the trigger and other genes on the Y chromosome are required for normal testi






9. Helps relieve strain from the DNA double helix when helicase untwists it at the replication forks - causing tighter twisting ahead of the forks.






10. Traits that are alternatives to the wild type because they are due to alleles assumed to have arisen as changes - or mutations - in the wild-type allele.






11. A method that maps chromosomes and locates genes with respect to chromosomal features - such as stained bands - that can be seen in the microscope. Ultimately show the physical distances between gene loci in DNA nucleotides.






12. Special site on a DNA molecule which replication begins. Indicated by a specific sequence of nucleotides.






13. Disorder caused by structurally altered chromosomes - specifically a deletion in chromosome 5. A child born with this deletion is mentally retarded - has a small head with unusual facial features - and has a cry that sounds like the mewing of a cat.






14. A type of change in chromosome structure as a result of some sort of chromosomal breakage. Occurs when a segment within a chromosome reverses.






15. Genes located in organelles in the cytoplasm. Mitochondria and plastids contain small circular DNA molecules that carry genes coding for proteins and RNA and do not display Mendelian inheritance. For example - almost all the mitochondria come from th






16. Offspring that have new combinations of their parent'S phenotypes. When 50% of offspring are recombinants - geneticists say that there is a 50% frequency of recombination and is observed for any two genes that are located on different chromosomes.






17. Adenine doubles bonds thymine and guanine triple bonds cytosine.






18. An aneuploid condition. Usually the result of an extra chromosome 21 so that each body cell has a total of 47 chromosomes. Also termed trisomy 21. Includes characteristic facial feature - short stature - heart defects - susceptibility to respiratory






19. A compact object that is the inactive X in each cell of a female. Although female mammals inherit two X chromosomes - one becomes almost completely inactivated during embryonic development and lies along the inside of the nuclear envelope. Most genes






20. A human sex-linked disorder. A disease characterized by progressive weakening of the muscles and loss of coordination. Affected individuals rarely live past their early 20s. A result of the absence of a key muscle protein called dystrophin.






21. An enzyme that catalyzes elongation of new DNA at a replication fork. As individual nucleotides align with complementary nucleotides along a template strand of DNA - DNA polymerase adds them to the growing end of the new DNA strand one by one.






22. An enzyme that untwists the double helix at the replication forks - separating the two parental strands and making them available as template strands. This untwisting causes tighter twisting and strain ahead of the replication forks which is relieved






23. The process that accounts for the recombination of linked genes. Occurs while replicated homologous chromosomes are pair during prophase of meiosis I - one maternal chromatid and one paternal chromatid break at corresponding points and then are rejoi






24. A occasional mishap that may occur during meiosis in which the members of a pair of chromosomes do not move apart properly during meiosis I or sister chromatids fail to separate during meiosis II.






25. Phenotypically female but are sterile because their sex organs do not mature. When provided with estrogen replacement therapy - girls with Turners develop secondary sex characteristics.






26. The system for determining sex in grasshoppers - cockroaches - and some other insects. In these insects - there is only one type of chromosome - the X. Females are XX and males are XO. Sex of the offspring is determined by whether the sperm cell cont






27. Traits that depend on which parent passed along the alleles for those traits. An exception to the display of Mendelian inheritance.






28. The system for determining sex in most species of bees and ants. There are no sex chromosomes in these species - Females develop from fertilized ova and are thus diploid. Males - however - develop from unfertilized ova and are haploid; they have no f






29. The new strand of DNA moving in the direction away from the replication fork. Synthesized as a series of segments in contrast to the leading strand that elongates continuously.






30. 1. deletion 2. duplication 3. inversion 4. translocation






31. An enzyme that can start an RNA chain from scratch. Joins RNA nucleotides together one at a time - making a primer complimentary to the template strand at the location where initiation of the new DNA strand will occur.






32. A genetic map based on recombination frequencies.






33. Each nucleotide added to a growing DNA strand is a nucleoside triphosphate - which is a sugar and a base with three phosphate groups. The triphosphate monomers used are chemically reactive - partly because their triphosphate tails have an unstable cl






34. The two alleles for each gene separate during gamete formation.






35. A result of nondisjuction of sex chromosomes. Do not exhibit any well-defined syndrome but tend to be somewhat taller than average.






36. An enzyme that joins the sugar-phosphate backbones of the Okazaki fragments - forming a single new DNA strand.






37. A result of nondisjuction of sex chromosomes.






38. Or phages. Viruses that infect bacteria.






39. The segments of the lagging strand that get added to the template strand. The segments get joined together by DNA ligase.






40. A gene located on either sex chromosome. In humans - the term has historically referred specifically to a gene on the X chromosome so fathers pass sex-linked alleles to all of their daughters and none of their sons while mothers can pass sex-linked a






41. The short initial nucleotide chain put in place before DNA polymerase begins synthesizing in the 5' to 3' direction. May consist of either DNA or RNA. In initiating the replication of cellular DNA - the primer is a short stretch of RNA with an availa






42. The mammalian system for determining sex. The sex of the offspring depends on whether the sperm cell contains an X chromosome or a Y.






43. A chromosome is missing in a aneuploid cell.






44. A sex-linked recessive disorder. Defined by the absence of one or more of the proteins required for blood clotting. When injured - people with this disease have prolonged bleeding because a firm clot is slow to form. Patients receive intravenous inje






45. A type of change in chromosome structure as a result of some sort of chromosomal breakage. Occurs when a chromosomal fragment repeats a segment. In some cases - if meiosis is in progress - a deleted fragment may become as an extra segment to a sister






46. In this - all four strands of DNA following replication have a mixture of old and new DNA. Proved incorrect and support came out for the semiconservative model.






47. Helps in repairing and proofreading DNA. An enzyme that cuts out a segment of the strand of DNA containing damage - creating a gap which is filled in with nucleotides properly paired with the nucleotides in the undamaged strand by DNA polymerase and






48. The general term for a chromosomal alteration in which an organism has more than two complete chromosome sets. There are more specific terms like triploidy (3n) and tetraploidy (4n) indicating 3 or 4 chromosomal sets - respectively.






49. One of the first imprinted genes to be identified. Although this growth factor is required for normal prenatal growth - only the paternal allele is expressed.






50. The most common type of translocation. A type of change in chromosome structure as a result of some sort of chromosomal breakage. In this - nonhomologous chromosome exchange fragments.