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






2. 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.






3. 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






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






5. 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.






6. 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






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






8. 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.






9. A result of nondisjuction of sex chromosomes.






10. 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.






11. 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






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






13. 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






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






15. A genetic map based on recombination frequencies.






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






17. 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.






18. 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






19. 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






20. 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.






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






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






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






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






26. 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.






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. 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






29. 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






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






31. 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.






32. 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






33. 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






34. A chromosome is missing in a aneuploid cell.






35. 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






36. 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.






37. 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.






38. Or phages. Viruses that infect bacteria.






39. 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.






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






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






42. 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






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






44. 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






45. 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.






46. 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.






47. The most common phenotype in a natural population.






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






49. 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






50. 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.