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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 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






2. 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






3. 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






4. 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.






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






6. A genetic map based on recombination frequencies.






7. 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.






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






9. 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.






10. 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






11. A chromosome is missing in a aneuploid cell.






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






13. 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.






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






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






16. 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.






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






18. 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






19. 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






20. 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.






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 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.






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






24. 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.






25. 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






26. 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.






27. The most common phenotype in a natural population.






28. 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.






29. 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.






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






31. 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.






32. 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






33. 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.






34. 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






35. 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.






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






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






38. 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.






39. 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






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






41. 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






42. 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.






43. Or phages. Viruses that infect bacteria.






44. 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.






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






46. 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.






47. 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






48. 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






49. 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.






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