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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. 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.






2. Predicted by Watson and Crick. Suggests that when a double helix replicates - each of the two daughter molecules will have one old strand - derived from the parent molecule - and one newly made strand.






3. A molecule that binds unpaired DNA strands - after its been separated by helicase - and stabilizes them until they serve as templates for the synthesis of new complementary strands.






4. 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






5. A result of nondisjuction of sex chromosomes. Females are healthy and cannot be distinguished phenotypically from other females.






6. 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






7. 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






8. Nucleotide sequences found in eukaryotic chromosomal DNA that make up for the fact that DNA polymerases cannot replicate the ends of DNA strands since there is no 3' end there. Do not contain genes but rather the DNA has multiple repetitions of one s






9. 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






10. 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






11. Alleles of genes on nonhomologous chromosome assort independently during gamete formation.






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






13. 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.






14. 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.






15. 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.






16. DNA repair that involves cleaving by nuclease and gap refilling by DNA polymerase and ligase.






17. A chromosome is missing in a aneuploid cell.






18. 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.






19. An abnormal number of a particular chromosome. A condition that arises when an aberrant gamete (a result of nondisjunction) unites with a normal one at fertilization.






20. 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






21. A result of nondisjuction of sex chromosomes.






22. 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.






23. 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






24. 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.






25. 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.






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






27. 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






28. 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.






29. Y-shaped region at the end of a replication bubble where the new strands of DNA are elongating.






30. 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.






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






32. 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






33. An ordered list of the genetic loci along a particular chromosome.






34. A genetic map based on recombination frequencies.






35. The most common phenotype in a natural population.






36. A result of nondisjuction of sex chromosomes. In this case - it is the result of an extra X chromosome in a male - producting XXY. People have male sex organs - but the testes are abnormally small and the man is sterile. Some breast enlargement and o






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






38. According to this theory - Mendelian genes have specific loci (positions) on chromosomes - and it is the chromosomes that undergo segregation and independent assortment.






39. A chromosome is present in triplicate in an aneuploid cell.






40. A type of change in chromosome structure as a result of some sort of chromosomal breakage. Occurs when a chromosomal fragment lacking a centromere is lost. The affected chromosome is then missing certain genes.






41. 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






42. 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.






43. 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.






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






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






46. The various proteins that participate in DNA replication actually form a single large complex since many of the protein-protein interactions actually facilitate the efficiency of the machine as a whole.


47. 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






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






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






50. 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.