PUT ON YOUR SCAN-TRON FORM: EXAM # (NOT #3) AND YOUR NAME!!!! OR LOSE POINTS Choose the one alternative that best completes the statement or answers the question.

1. Which of the following is not a characteristic event of mitotic prophase?
     A) movement of chromosomes toward the cell's center
     B) chromatin condensation
     C) breakdown of plasma membrane
     D) formation of the spindle apparatus
     E) breakdown of nucleolus

2. Histones carry
     A) a small negative charge.
     B) a small positive charge.
     C) a large positive charge.
     D) a neutral charge.
     E) a large negative charge.

3. The basic unit of DNA packing is
     A) the nucleosome.
     B) nucleosomes and linker DNA.
     C) the chromosome.
     D) the DNA molecule.
     E) the histone protein.

4. What are the two primary phases of the cell cycle?
     A) prophase and metaphase
     B) G1, G2, and G3
     C) prophase and G1
     D) interphase and mitosis
     E) metaphase and interphase

5. What is the mechanism whereby chromosomes find one another during synapsis?
     A) Homologues join naturally at adjacent regions.
     B) Microtubules pull homologues together.
     C) Homologues combine as a result of nuclear fusion.
     D) Chromosomes are "glued" together by glycosaminoglycans.
     E) Actin filaments pull homologues together.

6. What organelle is the nuclear membrane continuous with?
     A) the endoplasmic reticulum
     B) the lysosomes
     C) the peroxisomes
     D) the plasma membrane
     E) the mitochondria

7. Which of the following is NOT considered a major contributing factor to increasing genetic variation in offspring?
     A) random mate selection
     B) gene reconversion
     C) crossing over in prophase I
     D) random lining up of chromosomes in metaphase I with regard to
          maternal and paternal chromosomes
     E) None of the above.

8. Your uncle gives you a barrel of marbles for your birthday. He informs you that there are 4,000 black marbles and 12,000 green marbles. If you are blindfolded, what are your chances of reaching in and pulling out two green marbles, assuming that you replace the first marble before making a second try?
     A) 1/4
     B) 1/16
     C) 3/4
     D) 1/2
     E) 9/16

9. What was Gregor Mendel's occupation at the time of his pea experiments?
     A) chemist
     B) certified teacher
     C) molecular biologist
     D) Augustinian monk
     E) mathematician

10. According to Mendel's first law, the gametes of a heterozygous individual will be
     A) all recessive alleles.
     B) 25% dominant alleles, 75% recessive alleles.
     C) all heterozygous alleles.
     D) all dominant alleles.
     E) half dominant alleles, half recessive alleles.

11. What is an allele?
     A) a gene which masks the effects of similar genes on different chromosomes
     B) a cross in which two different genes are considered
     C) an individual's visible traits
     D) one of two or more alternative forms of a gene
     E) a chromosome with the gene for pea color and pod shape

12. Which technique used by modern geneticists would be most helpful in determining whether a given human trait is dominant or recessive?
     A) pedigree analysis
     B) parental testcrossing
     C) backcrossing
     D) consanguineous data analysis
     E) testcrossing studies

13. Maple syrup urine disease is a rare inborn error of metabolism. It derives its name from the smell of the urine of affected individuals. If untreated, affected children die soon after birth. The disease tends to recur in the same family, but the parents of the affected individuals are always normal. What does this information suggest about the transmission of the disease?
     A) This is not a genetic disease at all.
     B) This disease is actually due to a bacterial infection.
     C) This disease is due to a dominant allele.
     D) The disease skips a generation.
     E) This disease is due to homozygosity for a recessive allele.

14. Mother and father both find the taste of a chemical called phenylthiourea very bitter. However, two of their four children find the chemical tasteless. From the information provided, what can you conclude?
     A) The inability to taste phenylthiourea is a dominant trait.
     B) Phenylthiourea is inherited as a semirecessive condition.
     C) The ability to taste phenylthiourea is a dominant trait.
     D) The ability to taste phenylthiourea is a recessive trait.
     E) Phenylthiourea is a codominant allele.

15. Mendel's genetics experiments examined the inheritance of traits in
     A) golden hamsters.
     B) white rats.
     C) Drosophila melanogaster.
     D) pea plants.
     E) Stratiomyia rufescens.

16. If in rhinos the horn length phenotype were produced by the accumulative effect of 4 genes from different loci, this would be an example of
     A) polygenic inheritance.
     B) codominance.
     C) conditional gene expression.
     D) multiple alleles.
     E) partial dominance.

17. Which sex chromosome complement is carried by patients with Klinefelter's syndrome?
     A) XYY
     B) XY
     C) XO
     D) XXX
     E) XXY

18. Which sex chromosome complement may be carried by an individual with terminal acne, low IQ and a significant arrest record?
     A) XXX
     B) XXY
     C) XY
     D) XO
     E) XYY

19. Imagine in Tyrannosaurus a rare disfunctional tooth formation allele hypothetically termed the "toothless" allele. Homozygotes (tt) have no teeth at all. Heterozygotes (Tt) have 100 three-inch teeth, and homozygotes (TT) have 100 six-inch teeth. This gene is exhibiting
     A) codominance.
     B) dominant lethality.
     C) partial dominance.
     D) dominant epistasis.
     E) recessive epistasis.

20. Which of the following is NOT a reason why recessive alleles are not observed in the phenotypes of heterozytes?
     A) The dominant allele produces so much product as to "swamp" the product
          of the recessive allele.
     B) The recessive allele is linked to the dominant allele.
     C) The allele's product (eg. enzyme) is much less functional and therefore masked
          by the dominant allele's product.
     D) The recessive allele is normal, but the product of the dominant allele inhibits
          the function of the recessive allele.
     E) The recessive allele codes for a nonfunctioning protein.

21. In the multiple allele series C+>Ch>c, dominance is from left to right as shown. In a cross of C+c X Chc, what proportion of the progeny will be Himalayan?
     A) 3/4
     B) 1/2
     C) 0 percent
     D) 100 percent
     E) 1/4

22. Which sex chromosome complement is carried by patients with Turners' syndrome?
     A) XY
     B) XXX
     C) XYY
     D) XO
     E) XXY

23. If Mexican Hairless dogs are interbred, the puppies show a ratio of 2/3 hairless to 1/3 normal; in addition, some deformed dead puppies are also born. What conclusion can you draw based on this data?
     A) The hairless gene is an example of a recessive lethal allele.
     B) The dogs appear to be homozygous for the normal hair trait.
     C) The dogs appear to be homozygous for the hairless trait.
     D) The hairless gene is an example of a dominant lethal allele.
     E) The dogs without any hair die of pneumonia prenatally.

24. The work of which of the following scientists stands out as the pivotal set of experiments that began to firmly establish that DNA was indeed the genetic material?
     A) Meselson and Stahl
     B) Wilkins and Franklin
     C) Miescher and Haeckel
     D) Hershey and Chase
     E) Watson and Crick

25. The Hershey-Chase experiment involved the use of two radiolabelled elements. One of these elements is found naturally in protein but never DNA, and the other is found in DNA, but not protein. What were the elements, respectively?
     A) sulfur and calcium
     B) calcium and nitrogen
     C) phosphorus and nitrogen
     D) sulfur and phosphorus
     E) phosphorus and calcium

26. Which of the following genetic metabolic diseases was studied by A.E. Garrod?
     A) multiple sclerosis.
     B) Cri-du-chat syndrome.
     C) muscular dystrophy.
     D) Hutchinson syndrome
     E) alkaptonuria

27. The chromosome of a bacterium consists mostly of
     A) middle repetitive DNA.
     B) satelllite DNA.
     C) highly repetitive DNA.
     D) cistochromatic DNA.
     E) unique sequences.

28. Chargaff developed the principle of base-pairing in 1950. He determined that there was a one-to-one ratio between both bases in which of the following?
     A) adenine/cytosine and guanine/uracil
     B) adenine/thymine and cytosine/uracil
     C) adenine/thymine and guanine/cytosine
     D) adenine/uracil and guanine/thymine
     E) adenine/guanine and uracil/thymine

29. According to Watson and Crick's model of DNA, the two strands making up the double helix are
     A) parallel in that both strands run in the 5' - 3' direction.
     B) perpendicular.
     C) parallel in that both strands run in the 3' - 5' direction.
     D) antiparallel.
     E) wound into a triplo-helix.

30. Which of the following is INCORRECT concerning middle repetitive DNA?
     A) It may contribute to the control of gene activity.
     B) Genes which code for molecules that the cell needs in large quantities
          during short times are often middle repetitive DNA.
     C) Each copy may be present from 200,000 to over 1,000,000 times in the
          DNA of a single cell.
     D) Transposons are examples of middle repetitive DNA.
     E) It is common in centromeric regions.

31. How many base-pairs are there per helical turn of the DNA molecule?
     A) 15
     B) 5
     C) 20
     D) 10
     E) 25

32. Which of the following events sets the reading frame for the translation process?
     A) termination
     B) initiation
     C) elongation
     D) translocation
     E) charging of tRNA

33. Which of the following is NOT a kind of RNA found in most cells?
     A) ribosomal RNA
     B) transfer RNA
     C) single stranded RNA
     D) double stranded RNA
     E) messenger RNA

34. What are the respective sizes of the large and small subunits of the ribosome?
     A) 60S and 40S
     B) 50S and 20S
     C) 80S and 40S
     D) 50S and 30S
     E) 70S and 30S

35. There is a linear relationship between the order of nucleotides in DNA and the order of amino acids in the protein. Therefore, the information in DNA, mRNA, and proteins is referred to as
     A) parallel.
     B) continuous.
     C) linear.
     D) antiparallel.
     E) colinear.

36. What is the amino acid that the start signal codes for?
     A) leucine
     B) threonine
     C) glycine
     D) methionine
     E) cysteine

37. Which of the following most accurately defines a gene?
     A) a segment of DNA that specifies a polypeptide
     B) a sequence of bases
     C) a segment of DNA or RNA that specifies a polysaccharide
     D) a 10-12 base long DNA oligonucleotide that specifies an enzyme.
     E) a sequence of nucleotides that extend in the 5'-3' direction

38. What is a cistron?
     A) that segment of DNA that codes for the leader cistern sequence
     B) that segment of DNA that codes for protein
     C) all nontranscribed regions of mRNA
     D) that segment of mRNA that codes for the protein
     E) that segment of DNA that serves a regulatory function

39. tRNA is different from mRNA in what manner?
     A) It is much larger.
     B) It can be found in the cytoplasm.
     C) It can be covalently linked to an amino acid.
     D) It is made of 4 unique bases.
     E) It is not transcribed from DNA.

40. The initiation tRNA, the small ribosomal subunit, and the mRNA initiator codon all make up the
     A) charging system.
     B) elongation complex.
     C) protein synthetase.
     D) initiation complex.
     E) termination sequence.

41. Which of the following is an example of posttranscriptional regulation?
     A) Alternative promoters may be used to drive the transcription of one gene.
     B) the storage of mature mRNA's in the cytoplasm until needed
     C) the addition of sugar residues in the golgi apparatus
     D) A and B only
     E) A, B, and C

42. Genes that are continuously transcribed are termed:
     A) permanent.
     B) facultative.
     C) continuous.
     D) circular.
     E) constitutive.

43. The set of genes which are expressed in the cells in response to a sudden shift to elevated temperatures are called:
     A) thermal shock activator genes.
     B) heat shock protein genes.
     C) temperature sensitive mutations.
     D) temperature sensitive genes.
     E) microwave genes.

44. Genes for products which are continuously transcribed are termed:
     A) regulated.
     B) permanent.
     C) inducible.
     D) nonregulated.
     E) constitutive.

45. Which of the following E. coli operons is repressible?
     A) try
     B) glu
     C) lac
     D) trp
     E) ara

46. The inducer binds to:
     A) the RNA polymerase, which then transcribes the genes of the operon.
     B) the repressor protein, which then dissociates from the operator.
     C) the promoter, which then induces translation.
     D) the promoter, which then allows transcription of the operon.
     E) the operator, which then binds to, and activates the structural genes.

47. Genes that are continuously transcribed are termed:
     A) circular.
     B) facultative.
     C) constitutive.
     D) continuous.
     E) permanent.

48. According to the operon model, what is the segment of the regulatory region which binds the repressor?
     A) the operon
     B) the regulator
     C) the initiator
     D) the operator
     E) the leader

49. For any gene, transcription rate is determined primarily by:
     A) the number of gene copies.
     B) the length of the gene.
     C) the length of the leader.
     D) the relative ability of the promoter to bind RNA polymerase.
     E) the availability of ATP.

50. Which of the following bind to the trp repressor forming a repressor complex which shuts down transcription of tryptophan?
     A) CAP
     B) cAMP
     C) trypotophan
     D) glucose
     E) CAP-Camp complex

Bio 105 3rd MT
Name ______________________________________________
Did you remember to put your Lab Instructor's name and the exam # on the ScanTron???

15 points
I. Describe the Griffith Experiment and tell me what it showed:
I. Describe the Messelson-Stahl Experiment and tell me what it showed:
I. Describe the Hershey-Chase Experiment and discuss implications of the information.

II. Show the mechanism by which an Inducible Operon works. (Upstream, Downstream)
II. Show the mechanism by which a repressable Operon works. Regulator Region
II. Show the mechanism by which the Hsp Operon works.

III. List the sub-stages for Meiosis Prophase I, in sequence, and tell me what identifys each stage.

IV. If you were given the following sequence of nucleotides in DNA, what would be the amino Acid sequence for the polypeptide? Use the table to determine the Amino Acid Sequence of the polypeptide specified? (If it says stop. don't do it, just continue)
Nonsense Strand: TAC GAT CAT TAT AGC TAT ACA CCA ATA CCC AAA CAC
Sense Strand: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Polypeptide Sequence:_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

V. Draw the stages of the cell cycle, in order.

VII. Draw the chromosome arrangement for the one of the stages of mitosis for an organism where 2N =4.or 2N = 6

VIII. Discuss the process of protein synthesis when you have mouse ribosomes, rabbit messenger RNA and human transfer RNA, including the meanings of the terms: 3' & 5'; 3' poly A tail, 5' G-cap, initiation, elongation, translocation terminatiion.

IX. Draw the chromosome arrangement for the one of the stages of Meiosis for an organism where 2N =4.or 2N = 6