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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. The ___________ two genes are - the higher the probability that a crossover will occur between them and therefore the higher the recombination frequency. This process can occasionally break the physical connection between genes on the same chromosome






2. 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






3. 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.






4. 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






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






6. 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.






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






8. 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.


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






10. Or phages. Viruses that infect bacteria.






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. 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.






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






14. 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.






15. 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.






16. 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






17. 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.






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






19. 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






20. A genetic map based on recombination frequencies.






21. 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.






22. Can be distinguished from Watson and Crick'S semiconservative model in which the parent molecule somehow re-forms after the process of replication. Proved incorrect and support came out for the semiconservative model.






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






24. 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






25. 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.






26. 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.






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






28. An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells - thus restoring their original length and compensating for the shortening that occurs during DNA replication. Made possible by the presence in the telomerase of a short






29. 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.






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






31. 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.






32. 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






33. The most common phenotype in a natural population.






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






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






36. 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






37. 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.






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






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






40. 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.






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






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






43. 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






44. A cancer implicated by chromosomal translocations. The exchange of a larger portion of chromosome 22 with a small fragment from a tip of chromosome 9 produces a much shorted - easily recognized chromosome 22 - called the Philadelphia chromosome. Affe






45. 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.






46. 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.






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






48. Offspring that inherit a phenotype that matches one of the parental phenotypes.






49. The system for determining sex in birds - some fishes - and some insects. The sex chromosome present in the ovum determines the sex of offspring. The sex chromosomes are designated Z and W. Females are ZW and males are ZZ.






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