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






2. 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.






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






4. 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






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






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






7. 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






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






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






10. 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.






11. 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.






12. 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.






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






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






15. 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.






16. 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.






17. 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






18. 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.






19. 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






20. 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.






21. 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






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






23. 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.






24. Or phages. Viruses that infect bacteria.






25. 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






26. 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.






27. 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






28. A chromosome is missing in a aneuploid cell.






29. 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.






30. 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.






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






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






33. 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






34. 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






35. 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.


36. 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






37. 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.






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






39. 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






40. 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.






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






42. 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






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






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






45. The most common phenotype in a natural population.






46. 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.






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






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






49. 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






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