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GRE Chromosomal And Molecular Basis Of Inheritance

Subjects : gre, science, biology
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  • Answer 50 questions in 15 minutes.
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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. 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.






2. 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.






3. 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.






4. 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.






5. 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.






6. 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.






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






8. 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






9. 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.






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. 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






12. 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






13. 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






14. A result of nondisjuction of sex chromosomes.






15. 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






16. 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.

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17. Or phages. Viruses that infect bacteria.






18. 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.






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






20. A chromosome is missing in a aneuploid cell.






21. 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






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






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






24. 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






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






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






27. 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.






28. 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






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






30. 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.






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






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






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






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






35. 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.






36. 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.






37. A change in genotype and phenotype due to the assimilation of external DNA by a cell.






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






39. A genetic map based on recombination frequencies.






40. 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






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






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






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. 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.






45. 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






46. The most common phenotype in a natural population.






47. 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.






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






49. 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






50. 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